Bulletin BULLETIN of the ILLINOIS NATURAL HISTORY SURVEl HARLOW B. MILLS, Chief The Pseudoscorpion of Illinois C. CLAYTON HOFF ""''^^^m, ^/% Printed by Authority of the STATE OF ILLINOIS ADLAI E. STEVENSON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION NOBLE J. PUFFER, Director STATE OF ILLINOIS Adlai E. Stevenson", Governor DEPARTMENT OF REGISTRATION AND EDUCATION Noble J. Puffer, Director NATURAL HISTORY SURVEY DIVISION Harlow B. Mills, Chief \'oliime 24 BULLETIN Article 4 The Pseudoscorpions of Illinois C. CLAYTON HOFF Printed by Authority of the State of Illinois URBAN A, ILLINOIS June 1949 STATE OF ILLINOIS Adlai E. Stevenson, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Noble J. Puffer, Director BOARD OF NATURAL RESOURCES AND CONSERVATION Noble J. Piffer, Chairman A. E. Emerson, Ph.D., Biology George D. Stodrard, Ph.D., Litt.D., L.H.D., L. H. Tiffany, Ph.D., Forestry LL.D., President of the University oj Illinois L R. HowsoN, B.S.C.E., C.E., Walter H. Newhouse, Ph.D., Geology Engineering Roger Adams, Ph.D., D.Sc, Chemistry NATURAL HISTORY SURVEY DIVISION Urbana, Illinois Scientific and Technical Staff Harlow B. Mills, Ph.D., Chief Bessie B. Henderson, M.S., Assistant to the Chief Section of Economic Entomology George C. Decker, Ph.D., Entomologist and Head J. H. Bigger, M.S., Entomologist L. L. English, Ph.D., Entomologist C. J. Weinman, Ph.D., Entomologist S. C. Chandler, B.S., Associate Entomologist Willis N. Bruce, M.A., Assistant Entomologist John M. Wright, M.A., Assistant Entomologist H. B. Petty, M.A., Associate in Entomology Extension Section of Applied Botany and Plant Pa thology Leo R. Tehon, Ph.D., Botanist and Head J. Cedric Carter, Ph.D., Plant Pathologist J. L. FoRSBERG, M.S., Associate Plant Patholo gist G. H. Boewe, M.S., Assistant Plant Pathologist Robert A. Evers, M.S., Assistant Botanist Ph.D., Systematic Entomologist Associate Tax- Section of Faunistic Surveys and Insect Identification H. H. Ross and Head Milton W. Sanderson, Ph.D., onomist Lewis J. Stannard, Jr., M.S., Assistant Tax- onomist Leonora K. Gloyd, M.S., Laboratory Assistant Philip W. Smith, B.S., Laboratory Assistant Dorothy A. Moulton, Technical Assistant Section of Aquatic Biology George W. Bennett, Ph.D., Aquatic Biologist and Head William C. Starrett, Ph.D., Associate Aquat- ic Biologist D. F. Hansen, Ph.D., Assistant Aquatic Bi- ologist R. Weldon Larimore, M.S., Research Assist- ant Daniel Avery, Field Assistant Section of Forestry Willet N. Wandell, M.F., Forester and Head Lawson B. Culver, B.S., Associate in Forestry Extension Section of Game Research and Manage- ment Ralph E Yeatter, Ph.D., Game Specialist Frank C. Bellrose, B.S., Associate Game Spe- cialist Harold C. Hanson, M.S., Assistant Game Spe- cialist James S. Jordan, M.F., Assistant Game Tech- nician Section of Publications and Public Rela- tions Tames S. .Avars, B.S., Technical Editor and Head Blanche P. Young, B..A., Assistant Technical Editor Charles L. Scott, B.S., Assistant Technical Photographer '. Technical Library Marguerite Simmons, M..^., M.S., Technical Librarian Cooperative Wildlife Research {Illinois Department of Conservation and U.S.: Fish and JJ'ildlife Service, Cooperating) Paul J. Moore, B.S., Project Leader George C. Arthur, B.S., Project Leader Lysle R. Pietsch, M.F., Project Leader John C. Calhoun, B.S., Assistant Project Leader Consultant in Herpetology: Hobart M. Smith, Ph.D., Assistant Professor of Zoology, University of Illinois. This paper is a contribution from the Section of Faunistic Surveys and Insect Identification. (68424—2M—11-48) ,^.^^^2 FOREWORD During the latter part of 1946, all the zoological collections of the Illinois Natural History Survey were brought tojicther into one section, formerly the Insect Survey Sec- tiiiii, which was then renamed the Section of Faiinislic Surveys and Insect Identifica- tion. Previously, the Natural History Sur- vey had published a series of reports on the insects of Illinois and, at the same time, had developed the entomological collections. The double aim of the above reorganization was, first, to effect a well-balan.ed program in the Survey's faunistic activities with the hope that useful reports on the Illinois fauna would be made for groups other than insects and, second, to build up a comprehensive reference collection of study material for the identification of animal groups occurring in the state. A firm basis of expansion in several non- insect groups, such as the fish and mollusks. was provided several years ago by the ex- tensive Illinois collections of Stephen A. Forbes. Robert E. Richardson, and Frank C. Baker. Although in recent years certain other groups, especially the arthropods and reptiles, have been fairly well collected in the state along with the insects, our collec- tions of many forms are at a beginning level. The general aim for all groups is now the one that has been developed for the insects: to build up as extensive and inclusive a col- lection of Illinois species as possible, and to supplement this with representatives of other North American genera and species in each group. We feel fortunate in presenting this ac- count of the pseudoscorpions of Illinois as the first report of the expanded part of the program. In 194.? we began a co-operative undertaking with Dr. C. Clayton Hof-f. then at Quincy College, Quincy, Illinois, with the view of investigating the pseudoscorpion fauna of the state. At that time we were making extensive ground cover samples in connection with certain insect projects, and this activity dovetailed very well with a sur- vey of the pseudoscorpions. Dr. Hoff re- ported such unusual findings, and a fauna so much more extensive than had been ex- pected, that we soon decided to make his study the basis of a thoroughgoing faunistic report on the group for Illinois. This decision was strengthened by the very apparent need for such a study of the pseudoscorpions. Up to about 1930 the tax- onomy of this group in North America was in a preliminary and superficial stage. It was not until comprehensive analyses of the known world fauna were presented by J. C. Chamberlin and Max Beier in the 1930's that a groundwork was laid for modern studies of the group. Since no detailed fau- nistic report has previously been prepared for any region on the North American con- tinent, we hope that this Illinois report will prove useful to many investigators. We are grateful indeed to Dr. Hoff for the identification of material and prepara- tion of the manuscript, and for contribut- ing much of his own time to this project. Members of our staff in the Section of Fau- nistic Surveys and Insect Identification have contributed materially to the project. Sev- eral of them have assisted with the field pro- gram and with adaptation of the manuscript to current Survey practices. Four total views of pseudoscorpions were prepared especially for this work by Dr. Carl O. Mohr, formerly Associate Entomologist and Artist. Mr. James W. Curfman assisted with the preparation, numbering, and letter- ing of the plates. Mr. Lewis J. Stannard, Jr., Mrs. Leonora K. Gloyd, and Mrs. Dorothy A. Moulton compiled the index and assisted in assembling the Illinois records, preparing the bibliography, and checking and integrating the manuscript. We have enjoyed throughout the help and co-operation of the Technical Editor, Mr. James S. Ayars, and Mrs. Drew S. Wetzel and Mrs. Blanche P. Young of his staff. Herbert H. Ross Systematic Entomologist CONTENTS BIOLOGY 413 Feeding Habits.—Enemies.—Development.—Maturity ami Reproduction. HABITAT PREFERENCES 415 Deciduous Forests.—Rock Outcrops.—Saml Dunes.—Swamps and Bogs.-—Domestic Situations. iDISTRIBUTlON 416 ! Widely Distributed Species.—Southern Species.—Northern Species.—Other Species. 'collecting METHODS 418 PREPARATION OF MATERIAL 422 MORPHOLOGY 423 Body.—Appendages.—Genitalia. ACKNOWLEDGMENTS 427 'classification 427 Disposition of Material.—Systematic List. 1 Key to Suborders 428 f.mwilies Tridenchthoniidae 429 Chthoniidae 431 Ideoroncidae 444 Syarinidae 444 Neobisiidae 444 Menthidae 447 Olpiidae 447 Garypidae 447 Cheiridiidae 449 Sternophoridae 449 CHERNETmAE 449 Atemnidae 485 Cheliferidae 485 LITERATURE CITED 494 INDEX 497 Ground cover or duff in woods such as these harbors a wide variety of pseudoscorpion species. When a sample is to be collected, the dry top leaves should be brushed away and the moist lower leaves and the top layer of soil scooped up. Samples from the lee ot a log are often unusually productive. The Pseudoscorpions of Illinois PSEUDOSCORPIONS are minute animals only a few millimeters long, with the general appearance of di- minutive scorpions except that they have no tails. They belong to the large phylum of joint-legged animals, the Arthropoda, and to the class Arachnida. which, in addition to the pseudoscorpions, embraces the spiders, mites, ticks, scorpions, and other related groups. Pseudoscorpions are seclusive in habit, occurring in soil cover and rotten logs, under bark, and in similar places out of doors: one species is found in houses. In their natural habitat, these little brown ani- mals arc difficult to see. especially when they ilraw in their legs and "play possum." In this position they look like little specks of dirt. Probably because pseudoscorpions are inconspicuous, few collections of the group have been made in the past, and the fauna, at least of North America, and especially of the central and north-central United States, has remained scantily known. Prior to the initiation of the present studies, only one list was available for this region, that of Kwing (1911), which contained records of six species from Illinois and two additional species from neighboring states. Two factors have contributed to a con- siderable expansion of our knowledge of this group for the Illinois region. The first factor was the work of J. C. Chamberlin and Max Beier, both of whom, about 19.50, made extensive contributions to the taxon- omy of the world fauna of the pseudoscor- pions, delineating the suborders, families, and genera clearly for the first time, and utilizing an abundance of new identification characters. The second factor was the de- velopment of the Berlese funnel method of collecting pseudoscorpions and associated small animals. This method, described on page 418, has made possible collecting of *Universlly of New Mexico, Albuquerque, N. \I. C. CLAYTON HOFF* large series of many species and obtaining for the first time what appears to be a fairly accurate representation of the total fauna of Illinois. At the present time the list of known Illinois species stands at 26. Un- doubtedly, other species will be found with additional collecting; the present study, based on over 5,000 specimens, represents about .550 collections. The object of this report is twofold, first to present illustrated keys and descriptions for the identification of species in this region, and, secondly, to summarize information regarding the distribution, biology, and habi- tat preferences of the species. As an aid in use of the keys, a section has been included on morphology, in which the structures now considered of major taxonomic importance are explained. Summarizing the distribution has been especially difficult because many identifica- tions made prior to Chamberlin's work are probably incorrect and should be rechecked before they are cited. Because of this situa- tion there is little accurate information to serve as a guide in foretelling what addi- tional described species may be collected in Illinois. In order to make this report of wide application, the keys have been made to include all the genera known from the central and northeastern portions of the United States and adjacent portions of Canada. BIOLOGY Available information on the development and habits of pseudoscorpions is meager and is based chiefly on the study of a few large species, most of them of the suborder Mono- sphyronida. Scarcely any biological informa- tion is available for the smaller forms be- longing to the suborders Diplosphyronida and Heterosphyronida. [413] 414 Illinois Natural Histokv Survi;v Bullrtin lol. 24. Art. 4 Feeding Habits Pseudoscorpions feed on small animals such as mites, ants, and a wide variety of other insects, as indicated by the many pseudoscorpions observed with such prey in the chelae of the pedipalpi or palps. The pseudoscorpion's mouth, located on a tubular structure called the rosirum, contains a sucking structure, the pharyngeal pump, for taking in liquid food. The pseudoscorpion grasps its prey with the palps. These pre- hensile organs are supplied with a venom apparatus that efifectively kills or anesthe- tizes the captured prey within a matter of seconds. The palps and chelicerae, together or singly, hold the prey to the mouth and the pseudoscorpion sucks the fluids from the body of its victim. The larger pseudoscorpions, especially Chelifer cancroides, make interesting pets. One may be kept in a small corked vial into which is released a fly occasionally. The pseudoscorpion will stalk the fly patiently for a long time ; then suddenly it will reach out a palp and seize the fly. A good-sized house fly will put up quite a struggle, sometimes flying around with the pseudoscorpion attached; sometimes the pseudoscorpion will be stretched out in mid- air, grasping the cork with one chela and the fly with the other; but in a few moments the battle is over, and the fly is completely quiet. Then the feast begins. Evidence to date indicates that no pseudo- scorpions live as ectoparasites on larger animals. Pseudoscorpions occur abundantly in mammal and bird nests, but apparently they are not parasitic on the mammals or birds but instead feed on small arthropods in the nests. Species have been reported as nipping man, but without inflicting any ap- preciable injury (Beier 1932c/, 1941 ; Feio 1941). Large numbers of species have been re- ported from beneath the wings or elytra of beetles, as well as from the bodies of other insects and birds, as described by Vachon (1940, 1947). These cases appear to be nothing more than phoresy, with the pseudo- scorpions feeding on mites and other soft- bodied arthropods associated with the larger flying insects and birds. Vachon forcefully expresses the idea that phoresy with few exceptions is confined to the females. He believes that phoresy is a response to in- sufficient food at a time when the females are carrying and feeding the larval young. Enemies While pseudoscorpions prey upon smaller animals, they are in turn the prey of larger animals, especially birds, as indicated by the frequency with which pseudoscorpion re- mains are recovered from the digestive tracts of birds. The part played in food cycles ap- pears to be the pseudoscorpions' claim to ecological importance. Development Pseudoscorpions have several distinct stages in their life history: (1) the egg, in most species carried by the female; (2) the larva, in most species also carried by the female; {?i) three stages of nymphs, which are free living; and (4) the adult. The pseudoscorpion female usually pro- duces only a small number of eggs, ranging from 3 or 4 to as many as 30. The eggs in most species are not laid indiscriminately, but are simply extruded from the abdomen and retained as a group attached to the base of the abdomen in contact with the external genitalia. As the eggs are laid, they are grouped in a single-layered rosette or around the periphery of a spherical mass. In either case the egg mass becomes enclosed by a thin membrane. As young develop within the eggs, the enveloping membrane is lost and the larvae assume positions with their heads toward the center of the rosette or spherical mass. Each of the first stage larvae has a sucking apparatus for feeding, and rudiments of the! appendages, nerve ganglia, and other struc-i tures. The larvae secure a nutrient fluid secreted from the maternal ovaries, whichi become modified for this particular function.) During the period of larval developmen^f the females of those groups in which tW larvae form a single-layered rosette remai| active, while the females in which the larva* are arranged in the form of a spherical mass have been observed to seal themselves in !i nest and remain inactive. The presence o: large amounts of yolk in the eggs of a few species (Essig 1929) suggests that the larvai in these groups develop without attachmeH' to the mother. As development continues, a second larva stage is formed. In this stage, the suckin; apparatus is atrophied and the larva ap parently lives on the food accumulated dur ing the first or feeding stage of larval df velopment. Also, during the second larvs stage, the appendages and other structure lun,-. 1949 Hoff: Pseudoscorpions of Illinois 415 )f the nymph f;railiially make their appear- ance. At the end nf the larval development, the first nymphal stage or protonymph escapes From the brood pouch and begins to lead an independent life. The protonymph has es- sentially the same general appearance as the iidult. T he continued development includes three molts, and the individual passes suc- .essively through the prrj/onymph, tleuto- •lympli. and trilonymph stages, to form finally the sexually mature adult stage. At the time of each molt, the nymph secludes itself in a silken nest for a period of 10 or 15 days, during which time distinct mor- phological reorganizations take place. The various morphological changes that occur Setween nymphal stages and between the tritonymph and the adult include the gradual addition of tactile setae on the palpal chelae and a gradual change in the shape of various body parts, such as the segments or pod- omercs of the appendages. The nymphal stages of one Illinois pseudoscorpion, Apoch- lli'/iiiiis tniiistus, have been discussed in detail by Hoff (1946/1); the various stages of another species, ('htlioiiius lelrachelatus. have been described bv V'achon (1941fl, 1941/;). -Vlaturity and Reproduction Adult pseudoscorpions are undoubtedly fairly long lived, living probably for 6 months to a year or two. This surmise is based on collecting observations and notes made on a few individuals kept in captivity. Few exact data over an extended period are available. As is true of their relatives, pseudoscor- pions are dioecious. The males and females are similar in appearance. With the possible exception of a few forms, such as the genus Microbisium, in which the males have never been found, they reproduce sexually; appar- ently in the Microhisium females reproduce parthenogcnetically. According to Beier (1932(/), mating takes place in the spring, during April and May, |but this information is based on the study of jonly a few forms in the holarctic region and [possibly cannot be applied to species from lother areas. Unfortunately, information Irclative to mating is from observations of a jfew species of Monosphyronida only, and iseneralizations cannot be made for the entire order. In the few species that have received jdetailed study (Kew 1912), the male and female perform a courtship dance as a part of the mating activity. During the period of marked sexual activity and the courtship dance, a spermatophorc is released by the male. Sperms from this spermatophorc are picked up by the female. About 1 month after the transfer of sperms from the male to the female, the eggs are extruded. HABITAT PREFERENCES Pseudoscorpions have invaded many dif- ferent habitats in almost every part of the world. For the most part, the smaller forms live in debris and fertile soil, the larger forms under stones, under bark of trees, in decaying vegetation, and abundantly in mam- mal and bird nests. One genus, Giirypus, is found usually along the seacoast under stones and among algae and seaweeds. Some species of pseudoscorpions occupy very particular and restricted niches. The habitat relationships of most Illinois pseudo- scorpions arc summarized below. A few species are omitted as a result of inadequate ecological data. Deciduous Forests The abundant microhabitats found in the forest, fig. 1, afford the favorite living con- ditions for pseudoscorpions in Illinois. l"he species inhabiting forest ground cover and decaying wood are among the most abundant and widely distributed of our pseudoscor- pions. Three species have been found only in ground cover and litter: Aprjchtlionius mnestus, Heteroclitlioniiu mitllispinosiis. and Miintlochthonius siiiiilersoni. Dactyloclu'liffr copiosus has been found in the same habitats, and one collection of this species was swept from vegetation. Five species have been found chiefly in rotting wood or under bark of logs and stumps: I'errucadithii spinosa, Lawpro- cluriiis ablotujits, Diiioclu-irus pallidus. Pse- liiphochffncs parvus, and Aciiminochernes crassopalpus. The last two are especially common in the rotten wood and debris of hollow trees. Two species, Paracherncs squarrosus and Microbisium confusum. are found both in ground cover and in rotting logs and stumps; Mirorhiruts iliiitdlus occurs in both habi- tats and also is conunon in cavities of hollow trees. lindcr bark of livitig trees, chiefly oak and hickory, occurs liiiochcUfer nigripalpus. 416 Illinois Natural History Survey Bulletin J'ol. 24, Art. 4 Fig. 1.—Woods at Starved Rock State Park, Illinois. Wooded hillsides offer a wide variety of habitat niches: ground cover, rotten logs, hollow trees, moss, and root tangles. All these are prospective pseudoscorpion habitats. Rock Outcrops Three species have been found associated with rock outcrops, fig. 2. These pseudo- scorpions live in the debris and leaf mold on the rock ledges or at the bases of outcrops. Chthonius tetrachelatus has been taken in association with limestone outcroppings ; Al undochthoiiius rossi and Larca granulata have been taken only around sandstone out- croppings. Sand Dunes Our only collections of Paisochelifer callus have been taken in grass and ground cover in sand dunes. Swamps and Bogs Microbisium brunneum has been taken in Illinois only in the moss and debris in tama- rack bogs of the northern part of the state and in cypress swamps of the southern tip. Domestic Situations Chelifer cancroides is never found in natural habitats removed from habitations of human beings. Around man, however, it is widespread and abundant, occurring in chicken houses, barns, dwellings, beehives, and nests of starlings and sparrows. DISTRIBUTION Pseudoscorpions are found in all parts of the world except in the arctic and the ant- arctic regions. They reach their greatest degree of development both in population numbers and in diversity of species in the tropics and subtropics. Many of the super- June. 1949 Hoff: Pseudoscorpions of Illinois 417 families or families are world-wide or nearly world-wide in distribution, with at least a few representatives on nearly every large land mass and with a concentration of closely related species on one or two of the conti- nents. Thus, the diplosphyronld superfamily Neobisiidea is holarctic. while the heteros- phyronid Tridcnchthoniidae and monosphy- ronid Atemnidae are typically circumtropi- cal. In the Tridenchthoniidae, however, we lind a few species in the nearctic region and in the Atemnidae a few species outside of the distinctly tropical regions. Most of the family and subfamily groups have repre- sentatives in a wide geographical area. Such a widespread distribution appears interesting in a group without apparent means of rapid dispersal. There are several possible ways, however, by which dispersal may be accomplished. The small forms are Fi^. 2.—Sandstone ledges in Starved Rock State Park, Illinois. Ory leaves and sparse grass accumulate on the ledges and in the crevices of these outcrops to form a thin, dry layer of organic material. A few animals, apparently especially adapted to these dry conditions, live here. One of the denizens of these ledges is the Illinois pseudoscorpion Mundochthonius rossi. 418 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 readily carried by air currents and even the larger species may on occasion be carried in this way just as are many of the insects and spiders. Many forms are no doubt transported by large insects and by mam- mals and birds. Man may be an important factor in distribution of some species, as indicated by the widespread domestic distri- bution of Chelifer cancroides, and by the many specimens of other pseudoscorpions taicen from merchandise at quarantine sta- tions along the seacoast (Chamberlin 1938). Whether any of these latter man-introduced species have ever become established in a new area is not at present known. As with other animal groups, the Illinois pseudoscorpion fauna contains some species that are widely distributed and even cosmo- politan, and others that are greatly restricted in their geographical ranges. It has seemed worth while to group most of the species taken in the state according to area of dis- tribution. The remainder are recorded from only one or two counties and the data rela- tive to distribution are possibly incomplete. It is possible that the rarity of some species is more apparent than real, and that the apparent rarity results from greatly re- stricted habitat niches or from an insuffi- cient number of collections. Additional in- formation relative to the distribution records of the various species may be found in the systematic section of this paper. Widely Distributed Species Ten species have been collected from a sufficient number of Illinois localities to in- dicate that they are widely distributed over the entire state. These include some of our very common forms: Apochthonius moestiis, Microbisium confusum, Lamprochernes ob- longus, Parachernes squarrosus, Pselapho- chernes parvus, Acuminochernes crassopal- piis, Mirochernes dentatus, Chelifer can- croides, Idiochelifer nigripalpus, and Dacty- luchelifer copiosus. Microbisium brunneum, associated with bogs or swamps, has been taken at the north- ern and southern extremities of the state but not in areas between. Among the species infrequently collected, Chthonius tetrache- latus and Illinicliernes distinctus have been taken from northern and southern localities. Southern Species Two species, Heterochthonius multispin- osus and Mundochthonius sandersoni, have been taken from only the southern tip of the state. J'errucaditha spinosa has been found only in the Mississippi River drainage area in the south-central and southern parts of the state. Northern Species To date Alundochthonius rossi has been found only in the northern fourth of the state. In the same category arc three other species that have been taken occasionally, Dinocheirus pallidas, Dinocheirus solus, and Paisochelifer callus. Other Species Six species that have been collected in- frequently are known from central or north- central counties in the state, from the vicinity of Urbana, an area from which we have collected a large number of samples, or from widely separated local areas. Similar in- tensive collecting in other areas may show these species to have a much wider distribu- tion in Illinois. The six species are Chtho- nius ischnocheles, Lamprochernes minor, Reginachernes ewingi, Reginachcrnes lyni- phatus, Larca granulata, and Chelanops { ?) corticis. COLLECTING METHODS Collecting of large pseudoscorpions, espe- cially those belonging to the suborder Mono- sphyronida, may be done by hand from the bark of trees and logs or by sifting soil, debris, and rotten wood. However, collect- ing of most pseudoscorpions in these ways is laborious and slow because of the low population density of some species and be- cause of the small size, seclusive habits, and light color of other species, especially those of the suborders Heterosphyronida and Diplosphyronida. The most efficient method for collecting pseudoscorpions is by the use of Berlese funnels, named after the Italian entomolo- gist Berlese, who first used them exten- sively. A Berlese funnel is a very simple apparatus, fig. 3, consisting of a fairly lony; funnel suspended wide end up, with a screen placed about a third of the way down the funnel, with heat applied either around the upper portion of the funnel or over the top of the funnel, and with a container of pre- servative, preferably 80 per cent ethyl alco- hol, around the small bottom opening. Leaf mold, bark scrapings, broken-up rotten June, 1949 Hoff: Pseudoscorpions of Illinois 419 wood, and other material suspected of har- boring pseudoscorpions is placed on the screen, the heat source is turned on, and after a day or so the pseudoscorpions leave the dried sample and migrate downward, dropping into the preservative. half-inch mesh. Clumps of moss, leaves, sod, and pieces of wood or bark are torn up by hand into small fragments as they are put into the sieve ; then this material is raked over the sieve and shaken, the sifted materia! being collected on a cloth or paper, fig. 4. STEAM LINES CLOTH COVER SCREEN SUPPORT METAL SHADE ETHYL ALCOHOL Fig. 3.— Sketch of a Bcrlese funnel, showiiig a diagrammatic view across the middle. The central figure shows an arrangement for a steam coil, the lower left for an electric light. The Berlcse funnel provides the most efficient method for collecting pseudoscorpions and certain other animals. Fig. 3 illustrates a funnel that has proved very satisfactory; it is 15 inches from top to bottom and the top has a diameter of 12 inches. The bottom opening, exactly seven- eighths inch in diameter, fits into a half-pint cream bottle, which makes an ideal container for the preservative. Three angled brackets or hangers are soldered inside the funnel to provide a rest for the screen, which is made of a quarter-inch or eighth-inch mesh hard- ware cloth; the mesh used depends upon the type of sample. A battery of several funnels in a rack will allow the collector to sample a hundred pounds or more of material in one operation. Samples of leaf mold or other material are brought into the laboratory in cloth bags. Before being put in the funnel, each sample is sifted carefully through a screen sieve of Pieces of wood or bark are knocked sharply against each other to dislodge any animals that might cling to them. The sifted mate- rial is then placed on the screen in the funnel and piled up around the sides to leave a small open space in the center of the screen, fig. 5. This central opening allows the easy migration of animals in the upper part of the sample down into the bottom part of the funnel. The funnel so loaded is then placed in the rack for support, the bot- tle with preservative is placed under the nar- row end, and heat is applied. Funnels in position in rack are shown in fig. 6. If steam is used as a source of heat, the small copper lines that conduct it act as a partial support for the funnel by encircling it about half way between the screen and the top; a piece of cloth is tied tightly over 420 Illinois Natural History Survey Bulletin Vol. 24, Art. 4 Fig. 4.—Sifting Berlese samples. Preparatory to putting material in the funnel, bark and rotten wood are broken up and these and leaf mold sifted through a coarse screen. The sittings are put in the funnel. the top of the funnel, fig. 3. If an electric light or a choke coil is used for heating, it should be hung directly over the center of the funnel and no cloth tied over the top. With a light or choke coil, it is often well to use a wide reflector that approximates in diameter the diameter of the top of the funnel. Care must be taken not to heat the sample too rapidly. Otherwise, moisture will con- dense in the lower part of the funnel and trap many of the animals working their way toward the bottom, or the heat may kill many of the organisms before they have an opportunity to move out of the sifted ma- terial. A little experience furnishes the best gauge of the intensity of heat to be used. An application of heat sufficient to dry the sample in 4 or 5 days is usually satisfactory. As the sample dries, the organisms move out and downward, and finally drop into the bottle of preservative. The Berlese funnel is extremely useful for collecting many animals in addition to June. 1949 HoFF: PSEUDOSCORPIONS OF ILLINOIS 421 pseudoscorpions: groups of beetles, particu- larly Staphylinidae, thrips, Collembola, many groups of parasitic Hymenoptera, ants, milli- pedes, and centipedes, and a wide range of other minute animals that live in soil, sur- face cover, logs, or bark. Samples for the Berlese funnel may be collected at any time of the year. If col- lected during the warm months, they should be brought to the laboratory and placed in the funnels within a day or two; otherwise considerable loss of population occurs within the samples. If collected during the cold months, they may be kept in cold storage for a week or two with little loss. The following suggestions may prove helpful in picking up samples. For leaf mold samples, scrape off and discard the dry sur- face leaves and scoop up the lower, rotted layers of leaves together with an inch or two of the adjacent soil. You may en- counter especially good samples where leaves iiave blown in along the edge of a log (see frontispiece). In such a situation, take some of the log bark with the sample. Collect rotten log samples in large hunks and break them up in the sieve. From either standing stumps or fallen logs in which the wood is still too hard to break up, collect the loose bark, as it is often quite productive. Fre- Fig. 5.—Material to be sampled is placed on the sieve in the funnel and piled high around the edges; a small opening is left in the center. This arrangement allows an exit to the bottom for pseudoscorpions and other animals that might otherwise he trapped on top of the debris. 422 Illinois Natural History Survey Bulletin I'ol. 24, Art. 4 quently if you roll a log over, you may find animal runs under it; the debris and earth under and around these runs, together with animal nests, frequently give unusual catches. Probably the most productive single type of sample is that taken from the interior of a standing hollow tree. At the bottom of the hollow you may find a foot or more of fine, rotten, woody material that you can scoop out by reaching through a break in the base of the tree. A 50- or 60-pound sample of this is almost sure to net many interesting forms. Occasionally you may collect a wet sample, such as sod from a marsh or debris from a stream edge. If you allow it to remain in the sack for a few days it will usually dry out enough to permit sifting. Allow winter samples to thaw and dry be- fore you sift them. PREPARATION OF MATERIAL Most of the characters used in the iden- tification of pseudoscorpions can be seen only in proper orientation of the specimen and under moderate to high magnifications. For this reason it is necessary to prepare pseudo- scorpion specimens carefully so that they may be studied under the compound micro- scope. The following method has been found very satisfactory. First, remove from the animal the two chelicerae, the two palps, Fig. 6.—Funnels in position on rack. In this assembly, each funnel rests inside a double ring of copper tubing (as on funnel at extreme lower left) through which flows live steam. The steam produces the heat that dries out the sample and drives the animals out of it. Cotton or a small rag is tamped between the end of the funnel and the bottle of preservative to prevent escape of specimens. Jun,'. mo Hoff: Pseudoscorpions of Illinois 423 one of the first, and one of the fourth legs. Leave these in alcohol while the rest of the body is being treated. Next, puncture the body by making a slitlike cut in the side of the abdomen; then place it in a 10 per cent solution of potassium hydroxide. This step is intended to dissolve the muscles and in- ternal organs. Soak the body in cold hy- droxide solution for several hours, or in hot solution (heated in a boiling water bath) for a few minutes. The exact amount of time will depend upon the size and darkness of the specimen and can be gauged after a little experience. The object is to clear the preparation in hydroxide long enough to dis- solve out the internal material so that the preparation will be transparent, but not long enough to cause marked bleaching or de- coloration of the parts. After soaking the preparation in hydroxide, remove it to dis- tilled water and squeeze out the disinte- grated viscera by gentle pressure with needle or forceps. Alternately press and release the abdomen several times; this manipulation will cause a pumping action that will remove most of the internal material. Allow the preparation to soak in a fresh water bath for about a day to remove the last traces of dissolved material. After the washing proc- ess, dip the body in 1/50 normal hydro- chloric acid to neutralize the remaining hydroxide, and put it in 70 per cent alcohol. Next place the cleared preparation and the appendages previously removed in beech- wood creosote. After they have completely cleared and dehydrated, mount them in Canada balsam or clarite. In mounting the specimen, place the body with the ventral side uppermost and the two palps under one cover located a little to the left of the center of the slide, with suffi- cient room for the slide label to the left of the cover. Mount one of the palps with the dorsal side uppermost. Remove the chela from the other palp and spread the fingers wide apart. Mount this chela with the ex- ternal or lateral surface uppermost. If the body and palps are heavy and thick, support the cover glass with short pieces of capillary tubing or short pieces of finely drawn glass rod. -Mount the chelicerae and the previ- ously removed legs under a smaller cover to the right of the first. Do not use supports under this cover since the cover glass should rest on the legs and press them out flat for measuring. After clearing with hydroxide and before mounting some species or stages that are only lightly sclerotized, stain the body in acid fuchsin. Wash the material in dilute hydrochloric acid before putting it into this stain. After staining, wash the preparation in distilled water for some time to bleach out excess stain; then clear it in beechwood creosote and mount as directed above. Label all slides clearly, indicating collec- tion data and means of associating slide ma- terial with similar material in fluid. When an organism is identified, its name should he put on the slide label. MORPHOLOGY As an aid in the use of keys and the accu- rate identification of species, the important features of the external morphology of pseudoscorpions are outlined below. Addi- tional information is available in the works ot Chamberlin (1931^), Beier ( 1932A, r, ,1), and Roewer (1936, 1937). Body The body of a pseudoscorpion, fig. 7, is divided into two general parts, the cephalo- thorax and the abdomen. Both the body and the appendages bear many setae, the number and arrangement of which are of considerable taxonomic importance. In many species, the setae are slender and tapering, but in others they are modified in various ways. Commonly some of the setae are divided or branched at the tips and give somewhat club-shaped silhouettes; these setae are spoken of as clavate or subclavate in allusion to their general appearance. In some cases the branching occurs on only one side of a seta, and in others it extends down both sides of the seta to give a feathered effect. The cephalothorax is covered dor- sally by a shield or carapace that is with- out segmentation, although in some cases one or two transverse furrows subdivide the surface of the carapace. The mouth is at the anterior end of the cephalothorax and the feeding structure is retracted within a cavity in the anterior portion. In most species, one or more pairs of eyes are situated on or near the lateral margin of the cephalothorax; each eye has a single facet. The abdomen consists of 12 segments, of which the last is greatly reduced and very inconspicuous. In some species, as indicated in fig. 7, the eleventh and twelfth segments 424 Illinois Natural History Survey Bulletin Fol. 24, An. 4 cannot be seen in strict dorsal view. Each segment of the abdomen bears a dorsal ter- gite and a ventral sternite, but in many forms each of these is divided medially to form lateral sclerites or areas called tergal and sternal halves. The chaetotaxy and sculpturing of the tergites and sternites are often useful in taxonomy. The tergites are usually regular in arrangement and shape, but the anterior sternites are modified as a result of the presence of the genital opening and its accompanying structures. Toward the lateral end of each third and fourth sternite is a stigma or spiracle through which air is taken into the tracheal system. In the males of a few species, the lateral ends of some of the tergites are modified to form keels. A pleural membrane covers the abdomen laterally between the sternites and tergites. Appendages A pseudoscorpion bears six conspicuous pairs of segmented appendages, all arising from underneath the cephalothorax: a short pair of pincer-like cheliccrae; an elongate pair of palps, each ending in a pincer-like structure; and four pairs of legs, designated in descriptions by Roman numerals. Unlike most of the members of the Arachnida, the pseudoscorpions lack patellae on their appendages. Ghelicerae.—Each chelicera, fig. 8, is attached near the anterior end of the cephalothorax and consists of a basal seg- ment or podomere extended anteriorly to Fig. 7.—Sketch of a heterosphyronid pseudoscorpion to show the general body plan and appendages. The Arabic numerals designate segments of the abdomen; the Roman numerals indicate the four walking legs which arise from under the carapace on the venter of the cephalothorax. Abdominal segments 11 and 12 are not visible in a dorsal view of all species. Abbreviations used are c/i, chela; fe, femur; jf, fixed chelal finger; mf, movable chelal finger; mt, metatarsus; pb, pars basalis; pt, pars tibialis; ta, tarsus; ti, tibia; Ir, trochanter; tt, telo- tarsus. The coxa, which is basad to the trochanter on each leg, is not shown. June. I'M'J Hoff: Pseudoscorpions of Illinois 425 form a fixed finger and a second segment to form a movable finger. The dorsal surface of the base of the chelicera bears numerous setae. T hose that are of major significance spicuous galea or spinneret is attached near the end of the movable finger. This galea is said to function in spinning silk discharged from silk gland ducts that open at the tips ,— serrulr exterior flagellum Fig. 8. — Lamprni hernrs ohlnnyiu $ . Ex- terior or dorsal \'iew of chelicera. The setae important in taxonomy are indicated by the standardized (iesignations: b, basal seta; es, exterior seta; ijs, galeal seta; is, interior seta; /.(, laminal seta; sh, subbasal seta. in taxonomy have been designated by letters as shown in fig. 8. The setae vary among species and genera in number, position, and size. The lateral margin of the subventral surface of the cheliceral base bears a flagel- lum that consists of a few to many modified setae. The fixed finger is usually smaller than the movable cheliceral finger, bears an apical tooth and several denticles along the iimer margin, and is supplied with a longi- tudinal row of plates making up the serrula interior. With exception of the terminal three or four, the plates are frequently fused to form a so-called velum. The outer mar- gin of the fixed finger often bears a longi- tudinal keel or riblike structure known as the lamina exterior. The movable cheliceral finger has a prominent serrula exterior, con- sisting of a row of ligulate plates extending along nearly the entire length of the finger. The movable finger terminates in an apical tooth and the inner margin bears either a subterminal lobe or a series of denticles. Near the end of the movable finger is in- serted a galeal seta. In some groups, a con- Fig. 9. — Chelifrr cancroides 9. Lateral view of chelal hand of palp. The standardized symbols used for the tactile setae of the mov- able finger are as follows: b, basal seta; sb, subbasal seta; st, subterminal seta; /, terminal seta. On the fixed finger, e indicates exterior and / indicates interior; either is used in con- nection with /, sh, and the like. Thus, et is the exterior terminal seta, while // is the interior terminal seta. of the galeal branches or rami. When the galea is reduced or wanting, the ducts ap- pear to terminate in a tubercle or directly on the surface near the tip of the finger, fig. 25 6\ Palps.—The palps, fig. 7, are the most conspicuous appendages of the animal and are usually extended anteriorly. Each palp consists of several segments or podomeres: the coxa or maxilla, the trochanter, the femur, the tibia, and the chela. The chela has a movable finger that no doubt repre- sents an additional segment. The character- istics of the palpal segments most useful in taxonomy arc the general shape, the chaeto- taxy and sculpturing, the absolute size, and the length-width ratio. The last is fairly constant within each species and use of it is becoming increasingly important for the separation of closely related species. The segments of the palp, especially the chela, in some cases show sexual dimorphism, the 426 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 chela of the male frequently being larger and stouter than that of the female. The characteristics of the chela, fig. 9, are very important in classification. For a satisfactory study of the chela, a side view must be obtained. In such a view, the inner margins of both the fixed and movable fingers in most cases seem to be supplied with small contiguous teeth. In some cases, however, the teeth are alternately large and small, or variable in different parts of the margin. In the family Chernetidae, acces- sory teeth are borne on the outer and inner aspects of each finger near the marginal teeth. Great taxonomic significance is at- tached to the number and arrangement of the tactile setae of the fingers. In most species of pseudoscorpions the fixed finger has eight tactile setae and the movable finger has four, as shown in fig. 9. In other species, the number of tactile setae is greater or smaller. Each tactile seta is identified by the bulbous structure or areola from which it originates. One or both of the chelal fingers terminate in a venedens, or venom tooth, through which the venom is dis- charged. The venom duct can usually be traced proximally to the nodus ramosus, a dilation at the point where the small ducts form individual venom glands or reservoirs unite to form a single duct. Legs.—With respect to the legs, several characteristics such as the number of seg- ments, the nature of the joint between the pars basalis and the pars tibialis of the femur, and the nature of the terminal claws and chaetotaxy are important in classifica- tion. The number of segments in the legs is used as the basis for dividing the order Pseudoscorpionida into three suborders. In the suborder Monosphyronida, each leg has six apparent segments: coxa, trochanter, pars basalis and pars tibialis of the femur, tibia, and tarsus. In the suborder Diplos- phyronida, the tarsus of each leg consists of the proximal metatarsus and the distal telotarsus, so that the leg appears to be made up of seven segments. In the suborder Heterosphyronida, each first and second leg has a single tarsal segment, whereas each third and fourth leg has two tarsal segments. The nature of the legs in the heterosphyro- nid pseudoscorpions is shown in fig. 7. In general, the legs do not show sexual dimorphism except occasionally in modifica- tions of the tarsal claws of the first leg. The coxae of the legs are more or less rigidly attached to the cephalothorax and can easily be seen in ventral view. In some groups of the Heterosphyronida, one or more of the pairs of coxae bear spines. Some species have a minute seta-bearing tubercle located medially between the third and fourth pairs of coxae. Genitalia In addition to the structures already de- scribed, the genital organs are of some im- portance in taxonomy. The external geni- talia are located on the ventral surface of atrium coxal sac coxa IV Fig. 10. — Dactylocliclifer coplosus i . Im- portant structures of the male genital complex of the highly specialized type found in the Cheliferidae. the abdomen in the region of the second and third abdominal segments. The second sternite forms an anterior genital operculum, and the third sternite forms a posterior operculum. In the female, the genital complex is relatively simple. When better known, it will probably assume greater significance in classification. In some species, a pair of seminal receptacles may be distinguished. These are often in the form of elongated tubules. In many females, perforated plates, known as cribriform plates, are present. The shape, position, and number of these plates are characters used in systematic work. The seminal receptacle and the cribriform plates may be seen in many females cleared with hydroxide. In the male, the genital complex is more variable than in the female. The chaetotaxy of the opercula can be used on occasion as a specific character. In one group, the subfamily Cheliferinae of the family Cheli- feridae, the genital organs of the male are highly modified and specialized, fig. 10. In males of certain genera of this group, each fourth coxa contains a coxal sac either with Jinu, 1949 Hoff: Pskl'doscorimons of Illinois 427 or without a separated medial portion known as the atrium. The sclerotized statumen convolutum may or may not be invaginated anteriorly. When an anterior invagination occurs, the invagination contains a short sclerotized rod. ACKNOWLEDGMENTS This investigation has been made possible by the encouragement, co-operation, and assistance of many persons and organizations interested in the fauna of Illinois. Co-opera- tive effort has resulted in the accumulation of a greater number of collections of pseudo- scorpions than has ever been previously massed together at one time from any one state. The total number of collections made available for this study is about .?50, of which two-thirds are from the collections of the Illinois Natural History Survey. Pifty-seven collections were taken by the writer. Other collections were loaned by the Illinois State Museum, the Chicago Natural History Museum, the American Museum of Natural History, the Museum of Comparative Zoology, and the Cornell University Museum. The two museums last named made available type specimens and material collected and recorded from Illinois by H. E. Ewing. The writer wishes to acknowledge the as- sistance of the following persons who either collected pseudoscorpions or aided in some other way toward the completion of this study: Dr. H. H. Ross, Dr. T. H. Prison, Dr. H. B. Mills, Dr. M. W. Sanderson, Dr. M. -M. Leighton. Dr. A. E. Emerson, Dr. and -Mrs. Clarence Goodnight, Dr. Heinz A. Lowenstam, Dr. W. J. Gertsch, Prof. Nathan Banks, Dr. H. J. Van Cleave, Dr. V. E. Shelford, Dr. Carl O. Mohr, Dr. Kathryn M. Sommerman, Rev. Edbert Long, Rev. Robert Brinker, Dr. C. L. Remington, Mr. Willis E. Snow, Mr. and Mrs. W. V. Rapp, Jr., Dr. B. D. Burks, •Mr. Ciilbert M. Wright, Mr. Lewis J. Stannard. Jr., and Mr. Henry Dybas. The writer's sincere appreciation is especially extended to Dr. J. C. Chamberlin for infor- mation from his personal files of unpublished data and for the loan of specimens from his personal collection. This study was carried out chiefly while the writer was employed at Quincy College, Quincy, Illinois, continued while he was at the Colorado Agricultural and Mechanical College, Fort Collins, Colorado, and com- pleted while he was at the University of New .Mexico, Albuquerque, New Mexico. Deep appreciation is extended to these insti- tutions and their officials for facilities and time, without which this project could not have been completed. This study was aided also by a grant from the American Associa- tion for the Advancement of Science through the Illinois State Academy of Science. CLASSIFICATION The order Pseudoscorpionida or Chelone- thida, embracing all of the pseudoscorpions, is set of^ from other orders of the class Arachnida by the following combination of characters: carapace unsegmented, fig. 7, covering the cephalothorax ; abdomen seg- mented, not divided into pre- and post-abdo- men ; no sting on the abdomen ; chelicerae small and chelate; palps large and chelate; icspiration by means of simple tracheae. The order is divided into three suborders, each of which is represented in the fauna of Illinois. These suborders in turn are divided into a system of superfamilies, fami- lies, and lower categories in order to facili- tate grouping together related genera and demonstrate as far as possible natural rela- tionships. The general classification fol- lowed here is that outlined summarily in papers by Chamberlin {\929b, 1930, 193Ifl) and extended or modified by Beier (I932A, f, i7). These papers as a group give a com- prehensive outline of the classification of the entire pseudoscorpion world fauna, to- gether with full bibliographic treatment of the supergeneric names involved. Material in these papers is not repeated in the present paper, but instead the interested student is referred to them for further study. The bibliographic citations given in the present paper for species or genera are not intended to be complete. They consist of references to the original description, to papers in which are given diagnoses more nearly complete than the original, to publica- tions that contain important changes in tax- onomic position or nomenclature, and to papers that have definite reference to the fauna of Illinois. In this paper a complete diagnostic charac- terization of a species is given only for species that arc new or for which no recent and complete description is available in the literature. Kor other species, a summary of 428 Illinois Natural History Survey Bulletin Vol. 24. Art. 4 diagnostic characters is given and reference made to available extended descriptions. Measurements throughout this paper are in millimeters. Disposition of Material Most of the Illinois material recorded here and not otherwise noted is in the col- lection of the Illinois Natural History Sur- vey at Urbana, Illinois. Some material that belongs to other institutions is cited, and this usually is indicated by letters following the record. The letters used are as follows: CH—Collection of C. Clayton Hoff, Uni- versity of New Mexico, Albuquerque, N. Mex. CM—Chicago Natural History Museum, Chicago, 111. cr—Collection of C. L. Remington, Yale University, New Haven, Conn. cu—Cornell University, Ithaca, N. Y. HV—Collection of H. J. Van Cleave, Uni- versity of Illinois, Urbana, 111. IM—Illinois State Museum, Springfield, 111. jc—Collection of J. C. Chamberlin, For- est Grove, Ore. MCZ—Museum of Comparative Zoology, Harvard College, Cambridge, Mass. ws—Collection of Willis E. Snow, Ur- bana, 111. Systematic List To date there are Illinois records for 26 species of pseudoscorpions. Of these, two are known only on the basis of literature records. They are indicated by an asterisk in the following list. Suborder HETEROSPHYRONIDA Family Tridenchthoniidae Subfamily Tridenchthoniinae Tribe Verrucadithini Ferruca/lltha spinosa (Banks) Family Chthoniidae Subfamily Chthoniinae Tribe Chthoniini *Chthonius ischnocheles (Hermann) Chthonius tetrachelatus (Preyssler) Apochthonius moestus (Banks) Heterochthonius multhpinosus Hoff Mundochthonius rossi new species Mundochthonius sanderson't new species Suborder DIPLOSPHYRONIDA Family Neobisiidae Subfamily Neobisiinae Microbisitim brunneum (Hagen) Microbisium confusum Hoff Family Garypidae Larca granulata (Banks) Suborder MONOSPHYRONIDA Family Chernetidae Subfamily Lamprochernetinae Lamprochernes oblongus (Say) Lamprochernes minor new species Subfamily Chernetinae Parachernes squarrosus new species Pselaphochernes parvus Hoff Regiiiachernes ewingi new species Reginachernes lymphatus new species Dinocheirus pallidiis (Banks) new com- bination Dinocheirus solus new species Acuminochernes crassopalpus (Hoff) new combination Mirochernes dentatus (Banks) lUinichernes distinctus new species *Chelanops (?) cor^/f/f Ewing Family Cheliferidae Subfamily Cheliferinae Tribe Cheliferini Chelifer cancroides (Linnaeus) Idiochelifer iiigripalpus (Ewing) Paisochelifer callus (Hoff) Tribe Dactylocheliferini Dactylochelifer copiosus Hoff The keys to suborders, superfamilies, and families are designed to accommodate the entire fauna known at present from America north of Mexico. Where used, the sub- family keys are designed for the same fauna. Keys to tribes and genera are intended pri- marily to resolve the fauna of the central and eastern United States and adjoining portions of Canada. Keys to species include those taken in Illinois and in addition a few species that are known from surrounding states and that ultimately may be found in this state. Key to Suborders 1 . Each first and second leg with five segments exclusive of the coxa, and each third and fourth leg with six segments ex- clusive of the coxa, fig. 7 Heterosphyronida, p. 429 All legs with the same number of segments 2 2. Tarsus of each leg divided into metatarsus and telotarsus, so that the leg has six segments exclusive of the coxa Diplosphyronida, p. 443 Jinu . ]')4') Hoff: Psfl DoscoRi'ioNs oi' Illinois 429 Tarsus of each leg not divided, so that the leg has five segments exclusive of the coxa Monosphyronida, p. 449 Suborder HETEROSPHVRONIDA Members of this suborder may be recog- nized by tile single tarsal segment in the first and second legs and the two tarsal segments in the third and fourth legs. Hoth families represented in North America are known from Illinois. Both may be recog- nized by the extremely large chelicerae, fig. II, as well as by the key characters. Key to Families Most abdominal tergites with a double row of closely spaced, short and stout setae ex- tending completely across each segment; respiratory spiracles of third and fourth sternites oblicjuely placed and with differ- entiated guard sclerites, fig. 12£; body and palps very setose and granular; spines on coxae I and II, fig. 12D Tridenchthoniidae, p. 429 Abdominal tergites with only a single row ot long and slender setae across each segment; respiratory spiracles of third and fourth sternites transversely placed and without guard sclerites differentiated from the ster- nites, fig. 15D; body and palps no more than weakly granular; Illinois species with spines on coxa I, (ig. 15C, on coxa II, or on coxae II and III Chthoniidae, p. 431 TRIDENCHTHONIIDAE Pscudoscorpions belonging to this group can be recognized by the obliquely placed stigmata or respiratory spiracles, fig. 12£, that arc guarded by well-developed sclerites. Some exotic genera have only a single row of stout setae across the abdominal tergites. In America north of Mexico the family is represented by a single genus, J'errucailitlui. Diagnosed in relation to the world fauna by Chambcrlin & Chamberlin (1945), this genus is placed in the subfamily Tridench- thoniinae and tribe X'errucadithini. 1. VERRUCADITHA Chamberlin Alura Chamberlin (1926, p. 334). Genotype, by original designation : Clithonius spinosus Banks. (Name preoccupied by Alma Mnes- chler 1883.) I'crrucaditlia Chamberlin [19291;. p. 59), New name for Alura Chamberlin. ferruiaJitha Chamberlin. Chamberlin &: Chamberlin (1945, p. 22). Fi>;. 11. — A poilithnnlus moestus. an example of the suborder Hetcrosphyronida and the fainilv Chthoniidae. -Members of this genus possess movable chelal fingers on which the marginal teeth are broad, rounded, and contiguous. Only one nearctic species is known. Verrucaditha spinosa (Banks) Clithonius spinosus Banks (1893, p. 67). I'lrruiaditha spinosa (Banks). Chamberlin (1929A, p. 59), Chamberlin & Chamberlin (1945, p. 24), Hoff (1946/;, p. 103). In general, the following combination of characteristics serves to identify adults with- out mounting: body length 1.0-1.3 mm.; carapace with about 100 heavy lanceolate in- vesting setae, fig. \2B, and with the anterior c;:rapacic margin distinctly bilobed ; the pair of tactile setae on the dorsum of each chelal hand removed from the proximal margin of the hand by about one-fourth its length, figs. \2A, \2C; spines on coxae I and II, fig. \2D. Vox more extensive descriptions of this species, the reader is referred to Chamberlin & Chamberlin (1945)' and Hoff (1946i). Deutonymph.—The following descrip- tion is based on one individual. This stage has not been described previously in the literature. The deutonymph in general resembles the adult, length 0.82 mm., great- est width of abdomen 0.35 mm. Carapace anteriorly bilobed, each lobe with four stout marginal setae; eyes conspicuous. Chelicera very similar to that of the tritonymph as previously reported (Hoff I946i) except that there are three rather than two galea- likc processes near the end of the movable 430 Illinois Natural History Survey Bulletin Vol. 24, Art. iL^UJk Fig. 12. — I'crrucaditha spinosa. A, dorsal view of palp 5 ; B, setae of carapace ; I exterior view of chela, 3 ; O, coxal spines, 5. £, stigmata or respiratory spiracles, 9. finger and 10 rather than 14 plates in the scrrula exterior. Three to five spines occur on each of coxae I and II. Segments of palps weakly granulate and light yellow in color. Palp with femur 0.205 mm. long, 0.07 mm. wide; tibia 0.125 mm. long, 0.075 mm. wide; chela 0.4 mm. long, 0.082 mm. wide; depth of hand equal to width, length about 0.13 mm. ; movable finger 0.26 mm. long. Fixed chelal finger with seven tactile setae, ds and et near distal end, it and est near center, two setae near base of finger, and one {isb or ib) a little proximad to the mid-point of the dorsum of the hand; movable finger with two tactile setae near center. Marginal teeth similar in appearance to those of the adult; movable finger with 24 marginal teeth ; fixed finger with 1 1 acute and well- separated teeth in the distal half of the finger and 10 more nearly contiguous teeth on the proximal half of the finger margin. Distribution . — Verrucad'itha spinosa dues not occur abundantly in Illinois. Of eight records, four are from Adams County and one each from Brown, Jackson, Jersey, and Madison counties. The species is widely distributed in the central and southeastern part of the United States as shown by exist- ing records (Chamberlin & Chamberlin 1945). This species usually occurs in debris ar decaying wood of old stumps and logs i deciduous forests. One collection was take from "ground cover" and one from falle needles under an eastern redcedar tr« {J uniperus virginiana Linnaeus). Fig. 13. — Chthonius ischnocheles. Laters view of chela. (After Chamberlin.) /««,-. VU9 Hoff: Pseudoscorpions of Illinois 431 Illinois Records. — Adams County: 194.'!, ::. C. Hoff, 1 i ; Coe's Spring, Oct. 28, 1944, Rev. Edbert Long, \ i ,29 (1(},19,ch). Edwardsville: Sept. 24, 194.?, Ross & San- icrson, I immature. Gr..\fton : Sept. .^0, 194,?, Ross & Sanderson, I '' a i' Vi¥^ -VV-ft^ Fig. 15. — Apoc/ilhonius mocstus. A, palp in dorsal view, $ ; B, chela in lateral view, 9 ; C, spines of coxa I, 'i \ D, stigma on sternite 3, 9- Key to Genera Eyes absent; body length 2.3 mm 6. Genus? packardi Eyes present, or, if wanting or vestigial, body length less than 1.5 mm 2 Mesal portion of coxa I containing a group of well-separated spines, often in a row, each spine arising from an elongate slit, fig. 15C; intercoxal tubercles not present on the mid-line between any of the coxae 3 Mesal portion of coxa I without such spines; instead a comb of short spines or a group of short, feathered spines present on the mesal region of coxa II or coxae II and III, figs. 14D, 17£; a minute intercoxal tubercle bearing two small setae present between the junc- tion of coxae III and IV 4 Teeth along margins of chelal fingers short and broad, arranged close together, fig. 155 3. Apochthonius Chelal teeth widely spaced, alternately large and small, fig. 16C 4. Heterochthonius A group of well-separated, short, feathered spines present on each mesal margin of coxae II and III, figs. 14£, 14D 2. Chthonius Short coxal spines in the form of a comb, frequently united at bases, present only on the mesal portion of coxa II, figs. ( 17D, 18D 5. Mundochthoniusi 2. CHTHONIUS C. Koch Chthonius C. Koch (1843, p. 76). Genotype, i by subsequent designation of Simon (1S79): Obisium orthodactylum Leach. Chthonius C. Koch. Chamberlin (1925/.', p. 69), Chamberlin (1931fl, p. 212), Beie^^ (1932*, p. 43). The genus Chthonius is characterized by> the presence of an intercoxal tubercle, spineS'' on coxae II and III, and simple teeth (not' always contiguous) on the inner margins of the chelal fingers, figs. 14B, 14Z). Several subgenera have been outlined in the liter- ature. Of these subgenera, two are repre- sented in Illinois, each by one species. Other species in the genus are known from Georgia, North Carolina, and California. Key to Subgenera and Species Teeth of inner margins of chelal fingers largg acute, uncrowded, and somewhat conies^ and recurved; chelal hand appearing evenlj rounded on the dorsal margin as viewed" from the side, fig. 13. Subgenus ChlhoniuSi ischnocheles< June, 1949 Hoff: Pseudoscorpions of Illinois 433 Teeth o( inner margin-, of cheial lingers long and pointed, often well separated; in lateral view, the chelal hand displays a depression between the tactile seta of the dorsum of the hand and the linger base, fig. \AH. Subgenus Ephippiochlhoniiis tetrachelatus Subgenus Chthoniiis C Koch Clilhonius s. sir. C. Koch. Beier (1932A, p. 47). Members of this subgenus may be recog- nized by the lar^e. acute, and retroconical (pointin;: toward the base of the finirer) marfiinal teeth of the chelal fingers. The marginal teeth in some species arc well sepa- rated, at least in the distal part of the fi.\ed finger. The chelal hand has an evenly rounded contour as viewed from the side, there being no dorsal depression near the base of the fixed finger. A single species of the subgenus has been taken in the Illinois fauna. Chthonius isclinocheles (Hermann) V.hrlifcr isclinocheles Hermann (1804, p. 110). Chthonius PensyU'anicus Hagen (1869. p. 52). Chthonius prnnsylvanicus Hagen. Ewing (1911, p. 80). Chthonius ischnoeheles (Hermann). Cham- berlin (1929/', p. 71 ). Chthonius (Chthonius) ischnoeheles (Her- mann). Beier (1932*, p. 48). The species can be recognized from the rharacters given in the keys. The following idditional characters are listed by Beier (I932A). Ccphalothorax with 20 to 24 setae, the posterior margin with four to iix equally long setae. Setae of the tergites: ^:4:4:4:6:6:6:6. Marginal teeth of the pal- )al lingers pointed, triangular in outline, ind directed somewhat toward the base of he finger, fig. 13. Teeth of movable finger ilmost as strong as those of the fixed finger. Joxa II with at least 14 spines, coxa III vith at least 9 spines. Intercoxal tubercle vith two setae. Body length 1.6-2.4 mm.; )alpal hand 0.5 mm. long, 0.27 mm. wide; inger length 0.85 mm. Distribution.—Ewing (1911) reported a ingle individual of this species from Hill- •ry, Vermilion County, Illinois. No addi- ional collections have been secured in our ecent survey. The species has a wide dis- ribution and is reported from many locali- ies in Europe and from the northeastern "art of the United States (Chamberlin .929i). More Illinois records of this species vould be useful. Subgenus Ephippiochthonius Beier Ephippiochlhonius Beier (1930a, p. 323). Genotype, by present designation: Scorpio tetrachelatus Preyssler. Members of this subgenus are recognized by the presence of 18 setae on the carapace, of which two are on the posterior margin; in lateral view, the chelal hand displays a depression between the tactile setae of the dorsum of the hand and the finger base, fig. 14/i; teeth of chelal fingers are long, pointed, and usually well separated. A single species has been taken in Illinois. Chthonius tetrachelatus (Preyssler) Scorpio tetrachelatus Preyssler (1790, p. 59). Chthonius tetrachelatus var. maeulatus Menge. Stecker (1875. p. 314). Chthonius lonijipalpus Banks (1891, p. 164). Chthonius lonyipalpus Banks. Ewing (1911, p. 80). Chthonius tetrachelatus (Preyssler). Vachon (1941a, p. 442). Chthonius (Ephippiochthonius) tetrachelatus (Preyssler). Hadzi (1933a, p. 139; 1933/', p. 179), Hoff (1946A, p. 109). Individuals of this species may be recog- nized by the characteristics given in the key. especially by the shape of the chelal hand and the nature of the marginal teeth of the chelal fingers, fig. I4B. No detailed descrip- tion is included here, since the species has been treated recently and adequately by Hadzi (1933a, 19334)' and Vachon (1941a, 1941/-). The adults and most nymphs (but not the protonymph) in our collections agree well with those described by \'achon, except that the palpal segments of our specimens appear to be a little more slender than indicated in \'achon's drawings. I have examined a single protonymph that apparently belongs to this species. Un- fortunately, this protonymph was not asso- ciated with adults and, as a result, the identi- fication may be questioned. The individual dififers railically from the form described by \'achon (1941a, 1941/») as the protonymph of tetrachelatus. Possibly V'achon studied the last larval stage rather than the first nymphal stage, or protonymph, since his drawings do not appear to be made of ani- mals sufficiently developed to be proto- nymphs. Because of limited material and questionable identification, the protonymph I have examined that apparently belongs to this species is not described here. Distribution.—C.hlhotiius tetrachelatus « as taken by the writer in 1 1 collections in 434 li.MNOis Naturai, History Survey Bui.r.iiTiK I'ol. 24, Art. 4 the vicinity of Quincy, Adams County. In addition, a single individual was present In a collection made by Henry Dybas near Mooseheart, Kane County. The only other record available is from Herod, Pope County, and consists of the questionable protonymph mentioned above. The species has a wide distribution in Europe and north- ern Africa and has been reported from the New Ent;land states and Indiana in the L'nited States (Chamberlln \929b). Ecological data are available only for the collections taken in Adams County. Here the species was found chiefly in debris and leaf mold in woods, frequently in the vicinity of limestone outcroppings along the bluffs of the Mississippi River. Illinois Records. — Herod: Oct. 12, 19.?,?, ground cover in woods, Frison & Ross, 1 protonymph. Mooseheart: Sept. 1, 19.S9, Henrv Dybas, 1 specimen (cm). Quincv: Oct. 10, i943; Nov. 1, 1943; July 2, 1944; July 29, 1944; Aug. 13, 1944; all by C. C. Hoff, many specimens. 3. APOCHTHONIUS Chamberlln Apochthomus Chamberlln (1929*, p. 66). Genotype, by original designation: Clithov- ius mocstus Banks. Apochthomus Chamberlin (1929c, p. 152). Apochthonius Chamberlin. Beier (1932i, p. 41). The genus includes pseudoscorpions with the following characteristics: 22 to 24 setae on the carapace; four eyes; each coxa I with three simple seta-like coxal spines, each spine originating from a cleft or fissure on the surface of the coxa, fig. 15C; intercoxal tubercle lacking; chelicera with seven setae on the hand; marginal teeth of the chelal fingers small, contiguous, and occupying nearly the full length of the finger margins, fig. 15B. One species, moestus, occurs in eastern North America; two others in the north Pacific Coast region, occidentaUs Chamberlin and intermerlius Chamberlin. Apochthonius moestus (Banks) Chthonius morstus Banks (1891, p. 165). Apochthonius moestus (Banks). Chcmberlin (1929i, p. 67), Hoff (1944«, p. 125; 1945f, p. 311; 19464, p. 105). This species can be separated easily from other Illinois pseudoscorpions by the three coxal spines on each coxa I and by the small and contiguous marginal teeth on the chelal fingers. Diagnostic characteristics are illus- trated in figs. 11 and 15. Distribution.—Apochthonius moestus is widely distributed over Illinois; it has been identified in 65 collections from various parts of the state. The species appears to be distributed over most of the United States east of the Great Plains region. One of the more common pseudoscorpions in the eastern and central states, moestus is found very abundantly in the litter and debris on the ground in deciduous woods. It has also been taken from beneath the bark of decaying logs, in moss, and in mam- mal nests. Illinois Records.—Many specimens, taken throughout the year, are from Alham- bra, Alto Pass, Anna, Bond County, Burks- ville, Cadiz, Charleston, Collinsville, Dan- ville, Dolson (Clarksville), Eichorn, Foun- tain Bluf-f, Ganntown, Gef¥, Giant City State Park, Grafton, Herod, Kellerville, La Rue (Wolf Lake), Marshall, Monti- cello, New Salem State Park, Oakwood, Pocahontas, Quincy, Sherman, Starved Rock State Park, Urbana, Vienna, West Vienna, and White Heath. 4. HETEROCHTHONWS Chamberlin Hetcrochthonius Chamberlin (1929c, p. 153). Genotype by original designation: Apoch- thonius (Hetcrochthonius) crosbyi Chamber- lin. Hetcrochthonius Chamberlin. Hoff (1945f, p. 313). The members of this genus are similar to members of the genus ' Apochthonius but differ in having the marginal teeth of the chelal fingers with at least the distal teeth well separated and typically composed of alternating large and small teeth ; coxa I with three to six spines; carapace with 20 to 24 setae. Only two species are known in the genus, both from the eastern half of the United States, but only one is recorded from Illinois. Key to Species Body length 1.6-2.0 mm.; length-width ratio of palpal femur greater than 4:5, usually greater than 5:0, multispinosus Body length 1.3 mm.; length-width ratio of palpal femur 3:8 crosbyi Heterochthoniiis multispinosus Hoff Hetcrochthonius multispinosus Hoff (1945f, p. 314). This is the only pseudoscorpion thus far found in Illinois that has four to six (in one specimen, three) spines on each coxa I and June. 1949 Hoff: Pseudoscorpioxs of Illinois 4.^5 'the marginal teeth of the chelal fingers well spaced and alternately large and small, figs. 16B, \bC. ' Male.—The present individuals agree well with the type specimens. A study of specimens from Duke Forest, the type locality, and from Illinois shows that much greater variation occurs than was indicated in the study of the restricted type material. The following measurements and observa- tions are based on five males from Illinois. Body length 1.65-1.85 mm.; carapace 0.46- 0.51 mm. long, 0.43-0.47 mm. wide; abdo- men 1.15-1.35 mm. long, 0.65-0.7 mm. wide. Chelicera 0.33-0.39 mm. long, base 0.19- ,0.24 mm. wide; movable finger 0.2-0.235 ram. long; serrula exterior with 16 to 18 ligulate plates. Palp with trochanter 0.21- 0.215 mm. long, 0.12-0.125 mm. wide: femur 0.65-0.73 mm. long, 0.12-0.13 mm. wide, I length 5.4 to 5.65 times the width (ratio of ; 5.1:1 in type specimens, but ratio in other Duke Forest specimens similar to that in I many individuals from Illinois) ; tibia 0.26- 0.29 mm. long, 0.1,^-0.145 mm. wide, length 1.9 to 2.05 times the width; chela 0.93-1.05 mm. long, 0.185-0.2 mm. wide, length 5.0 'to 5,25 times the width: chelal hand 0,37- 0.42 mm. long, 0.195-0.205 mm. deep; mov- able chelal finger 0.56-0.65 mm. long (a little less than in the type specimens) and light yellow in color (not reddish-brown as I given in the original description). First leg with pars basalis 0.36-0,4 mm. long, 0.07- 0.075 mm. deep; pars tibialis 0.16-0.195 mm. [long, 0.065-0.073 mm. deep; tibia 0.21-0.24 imm. long, 0.05-0.057 mm. deep; tarsus 0.4— 0.43 mm. long. 0.045-0.05 mm. deep. Fourth leg with entire femur 0.57-0.63 mm. long, pars basalis 0.2-0.23 mm. deep; pars tibialis |0.I8-0.215 mm. deep; tibia 0.37-0.425 mm. long, 0.08-0.087 mm. deep; metatarsus 0.2- 10.225 mm. long, 0,65-0.70 mm, deep; telo- I tarsus 0,39-0.45 mm, long, 0.04-0.044 mm, 'deep; tactile seta removed from the proxi- mal margin of the tarsus by 0.12-0.13 mm., j being farther removed from the proximal .margin than indicated for the tvpe material {(Hoff 1945<-). j Fe.male.— In general, the female resem- |bles the male except that the body and ap- pendages are longer and that many of the i segments of the appendages are stouter. The I following measurements are of two females, leach measurement of one followed in paren- 1 theses by the corresponding measurement of the other. Bodv length 1.98 (1.85) mm. I carapace 0.53 (0.55) mm. long, 0.49 (0.52) mm. wide; abdomen 1.45 (1.28) mm. long, 0.56 (0.7) mm. wide. Chelicera with finger 0.285 (0.26) mm. long, serrula exterior with 17 (19) plates. Palp with trochanter 0,26 (0.26) mm. long, 0.145 (0.145) mm. wide; femur 0.81 (0.79) mm. long, 0.156 (0.15) mm. wide; tibia 0.335 (0.31) mm. long, 0.175 (0.16) mm. wide; chela 1.18 (1.15) mm. long, 0.245 (0.245) mm. wide; chelal hand 0.495 (0.48) mm. long, 0.255 (0.25) mm. deep; chelal finger 0.7 (0.68) mm. long. First leg with pars basalis 0.425 (0.405) mm. long, 0.087 (0.078) mm. deep; pars tibialis 0.2 (0.— ) mm. long, 0.08 (0.08) mm. deep; tibia 0.255 (0.25) mm. long, 0.061 (0.062) mm. deep; tarsus 0.46 (0.43) mm. long, 0.053 (0.051) mm. deep. Fourth leg with pars basalis 0.255 (0,22) mm. deep; pars tibialis 0.24 (0.2) mm. deep; entire femur 0.7 (0.67) mm. long; tibia 0.475 (0.44) mm. long, 0.105 (0.09) mm. deep; metatarsus 0.258 (0.24) mm. long, 0.08 (0.07) mm. deep; telotarsus 0.48 (0.46) mm. long, 0.053 (0.045) mm. deep; tactile seta 0.13 (0.135) mm. from proximal mar- gin of tarsus. Tritonvmph.—Much like the adult but smaller and segments of the appendages stouter. Body about 1.4 mm. long; carapace with both length and width about 0.4 mm. ; abdomen 1.1 mm. long, about 0.65 mm. wide. Chelicera with movable finger stouter than in the adult and with a subterminal nodule in which terminate a number of gland ducts; serrula exterior with 16 ligulate plates; movable finger 0.18 mm. long, basal setae apparently fewer than in the adult. Palpal segments conspicuously stouter than in the adult, color a little lighter, setae not so strongly developed. Palp with trochanter 0.19 mm. long, 0.1 mm. wide; both femora 0.5 mm. long, one femur 0.115 mm. wide, the other 0.12 mm. wide; tibia 0.215 mm. long, about 0.13 mm. wide; chela 0.78 mm. long, 0.175 mm. wide; chelal hand 0.29 mm. long, 0.17 mm. deep; movable finger 0.51 mm. long. Marginal teeth of chelal fingers much as in the adult except fewer in num- ber on the fixed finger and with less differ- ence in size between the alternating large and small teeth. Movable finger with three tactile setae: st not much distad from the mid-point of the finger, / about two areolar diameters distad from st, b removed from the proximal finger margin by less than twice the width of the finger at the level 436 Illinois Natural History Survey Bulletin FoI. 24, Art. 4 of b. Fixed finger with est about midway between isl and the finger tip ; ;/ about three areolar diameters distad from the level of est ; other setae much as in the adult except one of the setae on the dorsum of the chelal hand is wanting. The segments of the legs generally shaped as in the adult except much smaller and stouter; telotarsus of fourth leg subfusiform. First leg with pars basalis 0.258 mm. long, 0.066 mm. deep; pars tibialis 0.133 mm. long, 0.061 mm. deep; tibia 0.145 mm. long, 0.048 mm. deep; telotarsus 0.285 mm. long, 0.042 mm. deep. Fourth leg with entire femur 0.42 mm. long, 0.158 mm. deep; tibia 0.285 mm. long, 0.072 mm. deep; meta- tarsus 0.152 mm. long, 0.06 mm. deep; telo- tarsus 0.292 mm. long, 0.046 mm. deep; tactile seta removed from the proximal margin of the telotarsus by about 0.075 mm. Fig. 16. — Heteroclithonius multispinosus S . A, chela, dorsal view; B, chela, lateral view; C, more distal marginal teeth of chela. Distribution.—This species is infrequent in Illinois, having been taken in only four collections. Two of these collections were from Pope County, one from Jackson County, and one from Hardin County. The only other record is from Duke Forest, Durham, North Carolina, the type locality. The number of specimens found in the Illi- nois collections is small: four males, two females, and one tritonymph. This species has been taken only from ground cover, both in Illinois and in North Carolina. Illinois Records. — Cadiz: Nov. 6, 1942, Ross & Sanderson, 2 i , 19. Fountain Bluff: Feb. 22, 1933, Ross & Mohr, 1 im- mature. Herod: Oct. 12, 1933, Frison & Ross, 2i (13, ch); Oct. 18, 1944, Ross & Sanderson, 1 5 . Heterochthonius crosbyi (Chamberlin) Apochthonlus (Helerochtlionuis) crosbyi Cham- berlin (1929f, p. 153). This species is known only from North Carolina, but may eventually be found in Illinois. Recently the writer has been able, through the kindness of Henry Dietrich of the Cor- nell University Agricultural Experiment Station, to examine the holotype of Heter- ochthonius crosbyi. A comparison of crosbyi and multispinosus indicates that crosbyi is much smaller than multispinosus and that there is no possibility of confusing the two species. The following measurements were secured of the type of crosbyi and serve to supplement descriptive material given in the literature: body length 1.3 mm. (not 1.5 mm. as recorded in the original description, Chamberlin 1929f) ; each palp with femur 0.5 mm. long and 0.13 mm. wide; chela somewhat damaged but apparently about 0.78 mm. long; movable chelal finger 0.54 mm. long. 5. MUNDOCHTHONIUS Chamberlin Mundochthonnis Chamberlin (1929A, p. 64). Genotype, by original designation: Mundocli- tlionius erosidens Chamberlin. Mundochthonius Chamberlin. Beier (1932i, p. . 36). Members of the genus Mundochthonius may be recognized by the simple chelal teeth ; each tergite with usually four to eight setae; intercoxal tubercle with two setae; only coxa II with spines, figs. 17Z), 17£. Previ- ously, the genus was known from a number of species recorded from the western United States and from Japan. The two Illinois species described below constitute the first records of this genus east of the Rockies in North America. Key to Species Palpal femur longer than 0.3 mm.; chela longer than 0.5 mm.; length of palpal chela (with an occasional exception) at least 4.2 times the width; mesal comb of coxa II irregularly fused at base, figs. 17D, ME rossi Palpal femur always shorter than 0.3 mm.; chela shorter than 0.5 mm.; length of palpal June. 1949 Hoff: PsEunoscoRPioNS of Illinois 437 Fig. 17. — Miindoi htlionius rossi. A, teeth of distal part of margin of fixed chelal finger, holotype, i, arrow points proximad ; B, dorsal view of palp, paratype, c? ; C, lateral view of chela, holotype, i ; D, spines of coxa II, paratype, 9 ; /:, spines of coxa II, allotype, 9- chela always less than 4.2 times the width; mesal comh of coxa II fused symmetrically at base to form a fan-shaped structure, fig. 18D sandersoni Mundochthoiiiiis rossi new species Individuals of this species may be recog- nized by characteristics given in the key and illustrated in figs. MB. \7D. Male.—Unless otherwise indicated, ob- servations and measurements are based on four individuals. Body and palps light yel- low in color; body and appendages moder- ately slender; body length 1.05-1.2 mm. Carapace subcjuadrate ; two very weakly de- veloped eyes, each located about its own diameter from the anterior carapacic mar- gin; eyes hardly discernible in caustic- treated individuals. Anterior margin of carapace medially serrate with a small tri- angular, but variable, epistome ; anterior margin of carapace with six setae, of which the farthest lateral one of each side is located a little distance from the actual carapacic margin and close to the eye; pos- terior margin of carapace with two setae; total setae on carapace 18; carapace smooth except for netlike markings on the sides and sometimes along the posterior margin; cara- pace narrowed a little toward the anterior end, sides slightly conve.x ; length of cara- pace 0..^8-0.41 mm.; width a little greater than the length, 0.385-0.415 mm.; ocular width 0.38-0.39 mm. Tergites 1 and 2 each with four setae, tergites 3 through 9 each with six setae; tergites almost smooth, undi- vided. Medial setae of sternites much longer than lateral setae. Pleural membranes with regular rows of fine punctations. Length of abdomen 0.7-0.8 mm., greatest breadth 0.41- 0.48 mm. Chelicera.—A little darker than the cara- pace ; base with six setae, almost smooth. Length of chelicera 0.27-0.29 mm., width 438 Illinois Natural History Survey Bulletin Vol. 24. .hi. 4} of base 0.155-0.16 mm. Fixed finger basally stout, terminally narrowed and acute; tip of apical tooth brown and sclerotic; inner margin of finger with about 10 conical and acute denticles, usually the distal first and third much larger than the others. Movable finger moderately stout, gently curved, es- pecially near the tip; tip of apical tooth brown and sclerotic; spinneret represented by a rounded and poorly developed knob, apparently without gland ducts; galeal seta near the mid-point of the finger; inner mar- gin of movable finger with about eight denticles, much like those of the other finger in general appearance; serrula exterior with 13 to 15 ligulate plates; length of movable finger about 0.16 mm. Palp.—Fig. 17B. Moderately stout, chela slender; surface of segments smooth. Meas- urements given as the limits of range secured from four mounted individuals. Trochanter with flexor margin flatly con- vex in the center and with a few long setae; 1.5-1.7 mm. long, 0.92-0.103 mm. wide; length 1.6 to 1.7 times the width. Femur subcylindrical, extensor margin weakly con- vex or nearly straight in middle, more con- vex near the ends; flexor margin slightly convex beyond the mid-point ; setae of the flexor surface much longer than those of the extensor surface; 0.345-0.365 mm. long, greatest width just distad from the mid- point and equal to 0.085-0.09 mm., length between 4.0 and 4.15 times the width. Tibia with a few long and slender setae, especially on the extensor surface ; outer margin con- vex, inner margin weakly concave' to straight; widest across the extreme distal end; 0.177-0.2 mm. long (usually greater than 0.19 mm.), 0.105-0.11 ram. wide; length between 1.65 and 1.85 times the width. Chela with hand rather stout and fingers slightly curved; both margins of hand evenly convex, but with the flexor margin in most individuals conspicuously more convex than the extensor ; chela 0.55- 0.585 mm. long, 0.122-0.132 mm. wide, length 4.4 to 4.5 times the width ; chelal hand 0.203-0.21 mm. long; depth of hand nearly equal to the width; movable finger 0.36-0.385 mm. long. Viewed from the side, chelal hand, fig. 17C, with ventral margin moderately and evenly convex ; dorsal margin slightly convex, especially in the region of the tactile setae of the dorsum of the hand; fixed finger nearly straight, movable finger slightly curved. Marginal teeth of chelal fingers subquadrate at the distal end of the row and each tooth with a small cusp on the proximal corner; teeth of the proximal part of each row acuspid and somewhat rounded and flattened; teeth, fig. 17^/, regu- larly spaced along virtually the entire finger margin; each finger with usually between 50 and 60 teeth. Tactile setae of chela ar- ranged as indicated in fig. 17C Legs.—Measurements and observations based on two males; whenever the two show a significant difference, the measurement of the holotype is followed in parentheses by the corresponding measurement of a male paratype. Surfaces of segments smooth; setae not abundant except on the distal seg- ments; each coxa II with three (occasion- ally two) to five irregular and usually ser- rate spines, these fused at their bases. First leg with pars basalis subcylindrical, slightly deeper across the distal end than elsewhere, 0.192 (0.201) mm. long, 0.053 mm. deep; pars tibialis with weakly convex extensor margin, more convex flexor margin, 0.11 (0.115) mm. long, 0.05 (0.053) mm. deep; tibia subcylindrical, 0.118 (0.128) mm. long, 0.038 (0.041) mm. deep; tarsus tapering a little toward the distal end, 0.2 (0.217) mm. long, 0.034 mm. deep. Fourth leg with pars basalis very stout, 0.145 mm. deep; pars tibialis 0.133 (0.137) mm. deep; entire femur 0.327 (0.345) mm. long; tibia with the distal one-half of the flexor margin markedly convex, 0.247 (0.258) mm. long, 0.068 (0.071) mm. deep; metatarsus with both margins nearly straight, much less deep at the distal than at the proximal end, 0.1 (0.112) mm. long, 0.05 (0.051) mm. deep; metatarsus with a conspicuous pseudotactile seta on the extensor surface not far from the proximal margin; telotarsus subcylindri- cal, 0.208 (0.205) mm. long, 0.036 (0.035) mm. deep, a pseudotactile seta placed 0.068 (0.07) mm. from the proximal margin. Genital Complex.—Posterior operculum with about eight marginal setae; 20 to 25 setae superficially placed on each side of the genital opening; about 10 setae on the an- terior operculum. Female.—Unless otherwise indicated, observations and measurements are based on three individuals; measurements given are the limits of range. Like the male in virtually all respects; body length 1.08-1.2 mm. ; carapace 0.4—0.43 mm. long, width equal to length ; abdomen 0.4—0.55 mm. wide. Clielicera.—Like that of the male except j June, 1949 Hoff: Pseudoscorpions of Illinois 439 the spinneret is better developed, forming a nodule in which gland ducts appear to ter- minate; serrula exterior of 14 lifxulatc plates: length of chelicera 0.27-0.31 mm., width of base 0.16-0.185 mm.; movable finger vari- able, 0.165-0.195 mm. long. Palp.—Much as in the male but segments possibly a little larger and femur a little stouter. Trochanter 0.152-0.19 mm. long, 0.09.5-0.11 mm. wide, length 1.6.? to 1.7.? times the width; femur 0..?+-0..?95 mm. (allotype 0..?72 mm.) long, 0.091-0.102 mm. wide, length i.l to .?.9.? (allotype .?.9.?) times width; tibia 0.18.?-0.22 mm. long. 0.10.?- 0.129 mm. wide, length 1.7 to 1.8 times width; chela 0.55-0.635 mm. (allotype 0.58 mm.) long, 0.125-0.155 mm. wide, length 4.1 to 4.45 (allotype 4.45) times width: chelal hand 0.205-6.24 mm. (allotype 0.217 mm.) long, depth equal to width; movable finger 0.37-0.41 mm. (allotype 0.38 mm.) long. \'iewed laterally the shape of haml and fingers, as well as the dentation and chaetotaxy of fingers, essentially as in the male. Legs.—As in the male; spines of coxa 11 extremely variable, figs. 17D, 17£. Some- times longer than width of base (as in the allotype). Measurements given are of two individuals, each measurement of the allo- type followed in parentheses by the corre- sponding measurement of the female para- type. First leg: pars basalis 0.205 (0.216) mm. long, 0.055 (0.061) mm. deep; pars tibialis 0.112 (0.129) mm. long, 0.053 (0.061) mm. deep; tibia 0.129 (0.137) mm. long, 0.04 (0.044) mm. deep; tarsus 0.21 =i (0.23) mm. long, 0.0.?4 (0.036) mm. deep. Fourth leg: pars basalis 0.14 (0.155) mm. deep; pars tibialis 0.13 (0.137) mm. deep; entire femur 0.354 (0.38) mm. long; tibia 0.263 (0.29) mm. long, 0.069 (0.076) mm. deep; metatarsus 0.114 (0.118) mm. long, 0.052 (0.061) mm. deep; telotarsus 0.225 (0.235) mm. long, 0.036 (0.04) mm. deep; tactile seta located 0.076 (0.08) mm. from proximal margin of the telotarsus. Genital Cumplex.— Position of mounted specimens prevents description of the chaeto- taxy of the genital complex. However, one female examined in alcohol had 8 to 10 setae on the posterior operculum and 10 setae on the anterior operculum. The genital com- plex is simple and not sclerotized. Tritoxy.mph.—General appearance as in the male but appendages and body smaller, stouter, and lighter in color; cara- pacic epistome less prominent than in adult; tergal chaetotaxy much as in the adult; body 0.86 mm. long; carapace 0.29 mm. long, greatest width 0.28 mm., ocular and posterior width 0,26 mm.; abdomen 0.56 mm. long, about 0.35 mm. wide. Chelicera.—Details much as in the adult, but lighter in color, smaller, and stouter; about eight setae in the flagellum ; serrula exterior of 12 to 13 plates; length of cheli- cera 0.21 mm.; length of movable finger 0.133 mm. Palp.—Measurements of the single avail- able tritonymph as follows: trochanter 0.135 mm. long, 0.084 mm. wide; femur 0.267 mm. long, 0.075 mm. wide; tibia 0.152 mm. long, 0.091 mm. wide; chela 0.43 mm. long, 0.103 mm. wide; chelal hand 0.16 mm. long, 0.103 mm. deep; movable finger 0.29 mm. long. \'iewed laterally, fingers somewhat stouter than in male; dorsal margin of hand nearly straight; marginal teeth of same gen- eral nature as in male but slightly fewer in number. Movable finger with three setae, difficult to homologize definitely with the setae of the adult; one seta, possibly /, located slightly distad from the mid-point of the finger ; a second seta, possibly st, placed somewhat proximad from the mid-point of the finger and about three areolar diam- eters from the first seta; sb probably want- ing; b removed from the proximal finger margin by a distance about equal to the width of the finger at the level of the seta. Fixed finger with tactile setae much as in the adult except only one seta on the dorsum of the hand. Leys.—Segments essentially as in the adult except much smaller and stouter; each coxa II with four or five apparently simple spines, unequal in length. First leg: pars basalis about 0.15 mm. long, 0.049 mm. deep; pars tibialis 0.085 mm. long, 0.045 mm. deep; tibia 0.095 mm. long, 0.037 mm. deep; telo- tarsus 0.148 mm. long, 0.03 mm. deep. Fourth leg: pars basalis 0.11 mm. deep; pars tibialis 0.102 mm. deep; entire femur 0.258 mm. long; tibia 0.193 mm. long, 0.06 mm. deep ; metatarsus 0.08 mm. long, 0.045 mm. deep; telotarsus 0.159 mm. long, 0.038 mm. deep; seta 0.045 mm. from proximal margin of telotarsus. Deutonymph.—Observations based on one mounted individual. Body and append- ages smaller and stouter than in the trito- nymph; body not treated with caustic, and chaetotaxy of carapace and tergites not ob- 440 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 served ; body 0.75 mm. long ; carapace nearly 0.24 mm. long, about 0.29 mm. wide, pos- terior width 0.28 mm., ocular width 0.24 mm.; two weakly developed eyes; abdomen about 0.52 mm. long, 0.3 mm. wide. CheUcera.—Much like that of the trito- nymph ; flagellum with about six setae; slightly fewer marginal teeth on fingers and apparently fewer setae on the base; serrula exterior with 10 plates; movable finger 0.102 mm. long. Palp.—Segments fairly stout ; trochanter with the flexor margin irregularly convex, 0.103 mm. long, 0.068 mm. wide; femur distinctly subcylindrical in outline, 0.19 mm. long, 0.059 mm. wide; tibia with extensor margin convex, flexor margin weakly con- cave, 0.12 mm. long, 0.075 mm. wide; chela 0.325 mm. long, 0.083 mm. wide ; chelal hand 0.12 mm. long, 0.08 mm. deep; movable chelal finger 0.215 mm. long. Viewed later- ally, fingers appear fairly stout, both a little curved; 30 to 35 teeth on each finger, the teeth of the basal one-third of each finger distinctly rudimentary. Movable finger with two tactile setae, one (possibly st) located just within the basal one-third of the finger and the other (possibly t) located a little distance proximad from the mid-point of the finger. Fixed finger with setae somewhat as in the tritonymph except it and est relatively more basal in position, and only two setae (probably esb or eb wanting) in the group near the base of the finger. Legs.—Segments much smaller and stouter than in the tritonymph; spines of each coxa II variable, both simple and deeply incised spines present. First leg (measurements subject to possible error as the leg was not dissected from the specimen) : pars basalis 0.1 mm. long, 0.036 mm. deep; pars tibialis 0.065 mm. long, 0.036 mm. deep ; tibia 0.068 mm. long, 0.034 mm. deep; tarsus about 0.12 mm. long, 0.029 mm. deep. Fourth leg not in a position favorable for measuring. Holotype, male.^—Starved Rock State Park, Illinois: May 6, 1944, M. W. Sander- son. Allotype, female.—Starved Rock State Park, Illinois: Nov. 8, 1943, mossy debris on shelves. Ross and Sanderson. Paratypes. — Illinois.— Starved Rock State Park : Same data as for holotype, 5$, 19, 1 tritonymph; same data as for allotype, 2$, 19. White Pines Forest State Park: July 14, 1944, Frison & San- derson, 2 2,1 deutonymph, 2 tritonymphs. The following are additional Illinois records not included in the paratype series: Amboy: Dec. 6, 1945, Ross & Sanderson, 1 specimen. Mount Carroll: Smith Park, Dec. 6, 1945, 8 specimens. White Pines Forest State Park: soil cover in oak-hick- ory grove, Oct. 8, 1933, J. Alsterlund, 1 specimen. This species occurred in eight collections from the northern one-fourth of the state, all taken from ground cover and debris, especially around sandstone outcroppings. Many of the collections were from Starved Rock State Park and White Pines Forest State Park, where conditions are favorable for the preservation of the original fauna. Mundochthonius sandersoni new species This species can be identified by charac- teristics given in the preceding key and illus- trated in fig. 18. M.\LE.—Measurements and ratios repre- sent the limits of range of four individuals. Small, fragile, light yellow in color; body and appendages moderately stout; body length 0.75-0.9 mm. Carapace nearly square in dorsal outline; surface virtually smooth except marked on the sides by netlike lines; posterior margin straight, lateral margins usually a little convex; subtriangular epi- stome with a conspicuously serrate margin; four setae along the posterior carapacic margin; total setae on the carapace probably 20 (difficult to determine in specimens ex- amined) ; eyes vestigial, often entirely want- ing; length of carapace including the epi- stome 0.28-0.31 mm., greatest width about equal to the length, posterior width slightly less than the greatest width and ranging from 0.27 to 0.31 mm. Abdomen weakly ovate; tergites and sternites not divided; tergites 1, 2, and 3 each with four acuminate setae, more posterior tergites each with six setae; sternites 5 through 11 with 8 to 10 acuminate setae; setae of sternite 4 not determined in the male; length of abdomen 0.5-0.6 mm., width 0.3-0.37 mm. Pleural membranes finely and weakly papillose. CheUcera.—Large in ratio to the rest of the animal; slightly darker in color than the body and legs; 0.19-0.215 mm. long, width of base 0.115-0.13 mm.; base with six acuminate setae; lateral surfaces of base spinose, spines very short and readily seen only in relief; flagellum of about nine slender plumose setae. Fixed finger curved, apical June, 1949 HoFF: PSEUDOSCORI'IONS OF ILLINOIS 441 Fig. 18. — Mundochthonitis sandersoni. A, movable cheliceral finger, serrula omitted, para- type, 2 ; B, fourth leg, paratype, 9 ; C, lateral view of chela, holotype, <5 ; D, coxal spines, paratype, i ; E, dorsal view of palp, paratype, £ ; F, epistome, paratype, 9 ; G, epistoine, para- type, 9, another variation. tooth sclerotized and strong; nearly 12 acute teeth along the internal finger margin, the distal tooth very heavy, teeth toward base weaker; serrula interior reduced; Mov- able finger 0.1-0.13 mm. long; galeal seta long, inserted near the mid-point of the finger; apical tooth strong and sclerotic; galea represented by a prominent knob, which appears to be the terminus for a few gland ducts; usually between 8 and 10 acute, conical teeth along the distal one-half or two-thirds of the finger margin, with the most distal tooth larger than the others and located some distance from the next more proximal tooth; serrula exterior of 14 to 15 ligulate plates. Palp.—Fig. 18£. Light yellow in color with chela very slightly darker than the rest of the palp; moderately stout; segments with a few acuminate setae ; segments smooth except the dorsum of the chelal hand. Trochanter with irregular flexor margin, usually flatly convex in the central portion; 0.114-0.12.?" mm. long, 0.064-0.072 mm. wide, length 1.7 to 1.8 times the width. Femur subcylindrical ; inner margin slightly concave, outer margin nearly straight in the central portion but convex at each end, wid- est in the distal half; 0.22-0.25 mm. long, 0.064-0.072 mm. wide, length 3.45 to 3.65 times the width. Tibia subtriangular, wid- est across the extreme distal end; inner margin weakly concave, outer margin con- vex, usually a little flatly convex; 0.125- 0.15 mm. long, 0.077-0.084 mm. wide, length between 1.63 and 1.73 times the width. Chela with hand moderately stout; fingers slender, strongly but evenly curved in dorsal view; hand with outer margin flatly convex, inner margin more convex; 0.37^.42 mm. long, 0.091-0.102 mm. wide, length 4.0 to 4.15 times width; hand 0.136- 0.152 mm. long, 0.09-0.1 mm. deep; movable finger 0.25-0.285 mm. long, usually 0.27 442 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 mm. or more. Viewed laterally, dorsal and ventral margins of the hand weakly convex, tig. 18C, with the arc of the dorsal margin broken by the insertion of the two tactile setae, ib and isb, on the dorsum of the hand ; fixed finger in lateral view with straight inner margin, outer margin weakly convex, finger tapering rapidly in the distal one- fourth; movable finger more slender than the fixed finger. Both fingers usually with from 45 to 55 marginal teeth, varying in structure from the distal ones, which are subquadrate and each with a cusp on the proximal corner, to the proximal ones, which are rounded and acuspid ; teeth spaced along most of the finger margin. Tactile setae as in fig. ISC. Legs.—Moderately stout, light yellow in color; scattered acuminate setae, numerous only on the distal segments. A flat, semi- lunar blade on each coxa II, fig. 187); the blade irregularly and deeply incised along the margin and showing considerable inter- specific variation; blade wider than long; two or three minute short spines often located medially from the blade. First leg with trochanter 0.064—0.075 mm. long, length 1.23 to 1.33 times the depth; pars basalis subcylindrical, deepest near the dis- tal end, 0.118-0.133 mm. long, 0.04-0.045 mm. deep, length 2.9 to 3.05 times the depth; pars tibialis stout, 0.065-0.073 mm. long, length between 1.62 and 1.73 times the depth; tibia with extensor margin nearly straight, flexor margin weakly convex, 0.076-0.087 mm. long, 0.03-0.034 mm. deep, length 2.5 to 2.56 times the depth; tarsus tapering slightly toward distal end, 0.129- 0.145 mm. long, 0.025-0.027 mm. deep, length between 4.9 and 5.4 times the depth. Fourth leg with femur stout; chaetotaxy and color much as in the first leg; pars basalis 0.097-0.105 mm. deep; pars tibialis 0.09-0.098 mm. deep; entire femur 0.215- 0.24 mm. long, length 2.22 to 2.35 times the depth; tibia with the basal one-third of the extensor margin slightly convex, distal two- thirds of the extensor margin almost straight, flexor margin weakly S-shaped, greatest depth in the distal one-third; 0.158- 0.175 mm. long, 0.05-0.055 mm. deep, length 3.15 to 3.3 times the depth; metatarsus stout, a sensory seta near the basal one-fourth of the extensor margin, 0.061-0.072 mm. long, 0.037-0.041 mm. deep, length 1.6 to 1.95 times the depth; telotarsus subcylindrical, margins nearly straight, setae of flexor sur- face very numerous, 0.122-0.136 mm. long, 0.027-0.3 mm. deep, length 4.47 to 4.54 times the depth; seta of extensor surface of telotarsus removed by 0.03-0.035 mm. from the proximal margin of the segment. Genital Complex.—Anterior operculum with 10 to 12 scattered setae; posterior operculum with 12 to 16 marginal setae; 8 to 10 setae on the lateral rim of each side of the aperture; setae small and obscure. Fem.ale.—Unless otherwise indicated, measurements are based on seven individu- als. Essentially like the male in all details but much larger in actual size of body and appendages, appendages frequently a little stouter. Body length 0.9-1.15 mm.; carapace 0.31-0.33 mm. long, 0.29-0.35 mm. wide; abdomen usually 0.6-0.8 mm. long and 0.3- 0.45 mm. wide. Chelicera.—As in the male ; length 0.22- 0.245 mm., width of base 0.13-0.15 mm.; movable finger, fig. \^A, between 0.135 and 0.15 mm. long; serrula exterior with 14 ligulate plates. Palp.—As in the male. Maxilla usually 0.2-0.22 mm. long, about one-half as wide as long; trochanter 0.125-0.135 mm. long, 0.068-0.076 mm. wide, length 1.73 to 1.85 times the width ; femur 0.25-0.27 mm. long, 0.072-0.08 mm. wide, length 3.4 to 3.5 times the width; tibia 0.15-0.156 mm. long, 0.09- 0.093 mm. wide, length 1.67 to 1.71 times the width; chela 0.42-0.44 mm. long, 0.11- 0.18 mm. wide, length 3.68 to 3.89 times the width; chelal hand 0.158-0.168 mm. long, 0.11-0.118 mm. deep, the depth equal to the width; movable finger 0.275-0.295 mm. long. Legs.—As in the male. Measurements based on four individuals. First leg with trochanter 0.074—0.079 mm. long, length 1.18 to 1.27 times the depth; pars basalis 0.133-0.145 mm. long, 2.95 to 3.05 times the depth; pars tibialis 0.076-0.078 mm. long, length 1.68 to 1.81 times the depth; tibia 0.087-0.095 mm. long, 2.5 to 2.7 times the depth; tarsus 0.132-0.145 mm. long, length 4.35 to 5.4 times the depth, usually under 4.6 times the depth. Fourth leg, fig. 18B, with pars basalis 0.1-0.11 mm. deep; pars tibialis 0.09-0.1 mm. deep; entire femur 0.24-0.25 mm. long, length 2.15 to 2.3 times the depth; tibia 0.17-0.18 mm. long, length 3.1 to 3.25 times the depth; metatarsus 0.072-0.076 mm. long, 1.65 to 1.75 times the depth; telotarsus 0.13-0.14 mm. long, length 4.25 to 4.4 times the depth. June. 1949 HoFF: PSEUDOSCORPIONS OF ILLINOIS 443 Genital Complex.—Posterior genital oper- culum with seven or eight acuminate setae; anterior operculum with tour setae on each side anteriad and laterad to the genital aper- ture and two additional setae just anteriad to the pore. Holotype, male.—Herod, Illinois: April 18, 1944. Ross & Sanderson. Allotj'pe, female.—-Same data as tor holotype. Parat>pes.—Illinois.—Same data as for holotype. 8 i , 59 9. Herod: ground cover Fij5. 19. — Microl/isiiim confusum 9. An ex- ample of the suborder Diplosphyronida and the family Neobisiidae. in woods, Oct. 12, 1933, Prison & Ross, 1 S , 3 9. PouNTAiN Bluff: March 18, 1942, Ross & Sanderson, 1 9 . L.'^KE Glend.ale : ground cover, March 17, 1943, Ross & San- derson, U, 49 ; 1 <5, 19 (ch). La Rue: ground cover, April 19, 1944, Ross & Sander- son, 2 9 (nhs). Thebes: ground cover, April 19, 1944, Ross & Sanderson, 5 9 . There are two records in addition to the type series. Di.xox Springs: March 7, 1945, Ross & Sanderson, 1 specimen. VlENN.x: debris in woods. Jan. 25, 1947, B. D. Buries, 5 specimens. This species is dedicated to Dr. Milton \V. Sanderson of the Illinois Natural His- tory Survey staff. UNPLACED SPECIES 6. Genus? packardi Hagen Blot/inis packardi Hagen (1879, p. 399). Chthiinius packardi Banks (1895, p. 13). This species was described from material collected from caves in Kentucky and Indi- ana. Haven's description, although insuffi- cient to permit an accurate generic place- ment, indicates characters that provide means for the separation of this unplaced species from other northeastern species of Chthoniini, as given in the key. The types of this species appear to have been lost, being neither in the U. S. National Museum nor among the types of Hagen's other species at the Museum of Comparative Zoology, ;uid I have seen no material of the species. Since caves occur in Illinois, it is possible that this form may be found in the state. Suborder DIPLOSPHYRONIDA In North America, and with rare excep- tion elsewhere, members of this suborder may be recognized by the presence of the divided tarsus of each leg. Key to Superfamilies Movable finger of chelicera toothed along at least one-fifth of inner margin, fig. 25C Neobisioidea, p. 443 Movable finger of chelicera with either a single tooth or with a small group of teeth at apex of inner margin, fig. 27D Garypoidea, p. 446 Superfamily NEOBISIOIDEA Species belonging to this superfamily have the movable finger of the chelicera toothed on the inner margin; the plates of the ser- rula interior are not fused; and the sub- terminal setae of the pedal telotarsus are seldom simple. A single family, Neobisiidae, is present in our immediate fauna but two other families, Syarinidae and Ideoroncidae, have a very limited number of genera and species in the Rocky Mountain region and in California. Kev to Families 1. Venom apparatus developed in both fixed and movable chelal fingers Ideoroncidae Venom apparatus developed only in the fixed finger, fig. 24 2 2. Pleural membrane of abdomen smoothly and longitudinally plicate, never granu- late; suture between pars basalis and pars tibialis of femur IV at least slightly oblique to the long axis of the femur, . Syarinidae Pleural membrane ot abdomen granulate or granulo-striate; suture between parts 444 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 of femur IV truly perpendicular to the long axis of the femur Neobisiidae IDEORONCIDAE The genus Albiorix Chamberlin is re- ported from the southwestern part of the United States. A key to the species of the genus is given by Hoff (1945f). SYARINIDAE This family is represented in the Ameri- can fauna north of Mexico by one genus, Syarinus Chamberlin, with a limited number of species in the Rocky Mountain and Pacific Coast areas and by two very restricted genera, Hyarinus Chamberlin and Chitra Chamberlin, in California. NEOBISIIDAE Members of this family are identified by the presence of a venom apparatus only in the fixed finger, by the granulate nature of the pleural membranes, and by the vertical suture between the pars basalis and pars tibialis of the third and fourth legs. One subfamily is represented in Illinois, and a second is known from Arkansas. Key to Subfamilies Cheliceral galea present, at least almost as long as the apical tooth and having one or more branched processes, fig. 23 Ideobisiinae Cheliceral galea wanting or represented by no more than a sclerotic knob, fig. 25C Neobisiinae Subfamily IDEOBISIINAE While this subfamily has not been reported from Illinois, it is possible that, with further collecting, members of the genus Microcrea- ffris may be found in the state. 7. MICROCREAGRIS Balzan Microcieatjris Balzan (1891, p. 543). Geno- type, monobasic: Microcreagris ff'ffas Balzan. This genus, figs. 22, 23, may be separated from the other genera of the subfamily by the way in which the tactile setae t, st, and sb are scattered on the movable ohelal finger rather than clustered submedially. There is a single simple or branched galea. This genus is not reported from Illinois, but ozarkensis Hoff (1945a) has been de- scribed from Arkansas, and it is expected that this or related species of Microcreagris may eventually be found in Illinois. Subfamily NEOBISIINAE This subfamily forms a coherent group of forms in which the galea is either want- ing or greatly reduced and represented by no more than a sclerotic knob. A single genus is recorded from Illinois. A second genus, Neobisium Chamberlin, is included here since it has been reported from Ten- nessee. Key to Genera Four long tactile setae present on movable chelal finger and eight on fixed chelal finger, fig. 20 8. Neobisium Three long tactile setae present on movable, and seven on fixed, chelal finger, fig. 25S. . 9. Microbisiuiti 8. NEOBISIUM Chamberlin Neobisium Chamberlin (1930, p. 11). Geno type, by original designation: Obisium mus coram Leach. The genus, figs. 20, 21, can be recognized by the character given in the key, by the presence of tactile setae et, est, and it on the distal third rather than the distal fourth or fifth of the fixed chelal finger, and by the no more than moderately slender legs and palp. To date this genus has not been reported from Illinois but is represented by several species occurring in the southeastern states. One of these, tenuis Chamberlin, has been taken in Tennessee and there is a possibility that it or one of its congeners may ultimately be found in Illinois. Chamberlin (1930) described tenuis as a variety of carolinensis (Banks 1895). On the basis of differences pointed out by Cham- berlin in the original description of tenuis, it seems probable that this form should have specific rather than varietal status. The typical form of carolinensis is found in Georgia and North Carolina, while tenuis is confined to the mountain area of eastern Tennessee. Because of its habitat, tenuis is hardly to be expected in our fauna. 9. MICROBISIUM Chamberlin Microbisium Chamberlin (1930, pp. 10, 20). Genotype, by original designation: Obisium brunneum Hagen. Juii,-. 19-1-9 HoFF: PSKUDOSCORPIONS OF ILLINOIS 445 Fig. 20. — Neobisium carolinrnsis tenuis 6 Lateral view of chela. Fig. 21. — S'eohisium carolinensis tenuis <5 . Distal part of movable cheliceral finger. Fig. 22. — Microireagris ozarkensis i . Dorsal view of palp. Fig. 23. — Microcreagris ozarkensis $. Distal half of movable cheliceral finger; g, galea. Members of this genus are peculiar in that the number of tactile setae of the chelal fingers is reduced to three setae on the mov- able finger and seven setae on the fixed finger, hg. 25/?. Males have not been found in this genus. Three species are placed in the genus, two eastern ones treated below, and a third, piiri'tdum (Banks), from the southwestern states. These are treated by Hoff (1946(). Key to Species Palpal femur less than 0.4 mm. long, length between 2.42 and 2.89 times the width confusum Palpal temur more than 0.4 mm. long, length between 2.87 and 3.2 times the width brunneum Microbisium brunneum (Hagen) Ohisium brunneum Hagen (1869, p. 52). Microbisium brunneum (Hagen). Chamberlin (1930, p. 20), Hotf 19+6c, p. 494. Mierohisium brunneum (Hagen), in part. Hotf (1944rt, p. 125; 1946/;, p. 109). This species is readily identified by charac- ters indicated in the key. An extensive re- description of the species is given by Hoff {1946c). Distribution.—Microbisium brunneum has a wide geographic range in eastern Canada and in northern United States from New \ ork to Illinois. In Illinois its dis- tribution is markedlv discontinuous. It has been taken in 14 collections from Lake County in the northeastern corner of the state and in 1 collection each from Alexander and Pulaski counties, both in the extreme southern tip of the state. All collections of this species from Lake County were made from tamarack bogs. Of the collections from the southern tip of the state, one was taken from "dry forest" in the Horseshoe Lake Game Refuge near Olive Branch and the other was from "humus and soil from drier part of bank, cypress bottoms" near Karnak. The distribution seems to indicate that brunneum is associated w'ith acid soil and water and with deciduous coniferous trees in Illinois associated with either tama- rack or cypress. Illinois Records.—About 200 adults and nymphs of all sizes from several localities. Antioch : sphagnum moss in tamarack bog, Oct. 15, 1942, and Oct. 27, 1943, Ross & Sanderson. K.'\rn.'\k: humus and soil from drier part of bank, cypress bottoms, Feb. 24, 1933, Ross & Mohr. Olive Branch: Horseshoe Lake Game Refuge, dry forest, Dec. 2, 1943, Frison & Ayars. Volo: sphag- num moss in tamarack bog, Oct. 7, 1933, J. Alsterlund; sphagnum moss in tamarack bog, Oct. 27, 1943, Ross & Sanderson. Wau- coND.'i: ground cover in tamarack bog, March 16, 1933, Frison & Mohr; tamarack bog, ground cover, Oct. 20, 1943, Ross & Sanderson. 446 Illinois Natural History Survey Bulletin Fol. 24, Art. 4 Microbisiutn confusum Hoff Microbisium brunneum Hoff (non Hagen), in part (1944fl, p. 125; 1946*, p. 109). Mis- identification. Microbisium confusum Hoff (1946c, p. 496). Identification of this species can be made by the characteristics given in the Icey and illustrated in figs. 19, 25A, 255. In addition to the scheme indicated in the key, the fol- lowing will help in separating brunneum and confusum. M. confusum shows the follow- ing average differences when compared with brunneum: the body is smaller; the palp is smaller, less sclerotized, less deeply colored, and less polished; the palpal femur is con- spicuously smaller and stouter; the pedicle of the tibia is commonly less slender and the inner margin of the palpal tibia is usually more evenly rounded or convex ; and the chelal fingers appear stouter when viewed from the dorsum. Additional descriptive material is contained in the original descrip- tion (Hoff 1946f). Distribution.—Microbisium confusum appears to be the common species of the genus in the Mississippi River valley and the eastern United States. In Illinois it is the most widely distributed and most abun- dant species of all the pseudoscorpions and has been taken in 148 collections from all parts of the state. It occurs in forest soil and litter, and in decayed logs or stumps. The species is found associated with brun- neum in the tamarack bogs of northeastern Illinois. Illinois Records.—Many adults and nymphs taken during all months of the year are from Adams County, Alhambra, Alto Pass, Antioch, Apple River Canyon State Park, Astoria, Aurora, Bensenville, Brown- field Woods, Browning, Burksville, Burton, Cadiz, Caledonia, Charleston, Clarksville, CoUinsville, Cook County, Danville, Dixon Springs, Dolson, Elgin, Enfield, fountain Bluff, Fox Ridge State Park, Freeport, Galena, Geff, Giant City State Park, Graf- ton, Halfday, Havana, Herod, Highland Lake (near Grays Lake), Ivanhoe, Kamps- ville, Kell, Kellerville, La Grange, Lake Glendale, Lake Zurich, La Rue, Lincoln, Logan, Magnolia, Makanda, Marshall, Mascoutah, Mason Mound City, New Palestine, Palisades Palos Park, Peoria, County, Monticello, Windsor, Oakwood, State Park, Paloma, Pocahontas, Quincy, Ruma, Seymour, Sherman, Siloam, (Siloam Springs), Starved Rock State Park, Summit, Troy, Urbana, Ursa, Vienna, Volo, Wau- conda, Waukegan, White Pines Forest State Park, Winthrop Harbor, Zioji. Superfamily GARYPOIDEA Members of this superfamily are charac- terized as follows: the movable cheliceral finger, instead of being toothed on the inner margin, bears a simple, or occasionally a subdivided, subterminal lobe ; the plates of the serrula interior are fused basally to form a velum and only the terminal teeth are free ; the subterminal setae of the telotarsi are always simple and acute. Three families are represented in the United States but only one, the Garypidae, has representatives in the north-central part of the country. Fig. 24. — Microbisium brunneum 9. A, dorsal view of palp ; \B, lateral view of chela, poison gland (in fixed finger only) shown by dotted line. June. 1949 Hoff: Pseudoscorpioxs of Illinois 447 Key to Families 1. Venom apparatus developed in fixed finger only; at base of reduced or vestigial apical tooth of the movable finger is a groove, the receptor venedentis, into which fits the tooth or venedens of the fixed finger Menthiilae Venom apparatus developed in both fixed and movable fingers; movable finger without receptor venedentis - 2. Pleural membrane smoothly and evenly plicate; carapace usually not triangular; coxal area never widened posteriorly; setae of palpal femur and tibia con- spicuous, always slender and acute . Olpiidae Pleural membrane not smoothly and evenly plicate; carapace definitely triangular in shape, fig. 27C; coxal area with few exceptions much widened posteriorly; setae of the palpal femur and tibia short and inconspicuous; if acute, these setae are very short Garypidae MENTHIDAE This family is represented in America north of Mexico by a single genus, Mcntlitis Chamberlin, a few species of which occur in California. OLPIIDAE The family contains a few genera and species confined in the United States chiefly to the arid and semiarid regions of the South- west. GARYPIDAE TTT-y^ Fig. 25. — Microbisium conjusum 2. A, dor- sal view of palp; B, lateral view of chela; C, chelicera, movable finger; g, knoblike galea, showing silk ducts. A and B same scale as fig. 24. claws of the pedal tarsi ; the movable chelal finger has two tactile setae; pars basalis of legs I and II is never much longer than the pars tibialis; the femoral articulation of the first two pairs of legs is only slightly mobile; the investing setae of the palps are decidedly lanceolate. Only the following species of this genus is known to occur in North America. Larca granulata (Banks) Garyfus cjranulatus Banks (1891, p. 163). This family is characterized by a venom apparatus in each of the chelal fingers; in- vesting setae of palpal femur and tibia short and inconspicuous; pleural membranes gran- ular or with rugose striations, not evenly striated; carapace subtriangular ; abdomen broader than the cephalothorax. A single genus occurs in central and eastern United States. The only other nearctic genus, Garypus, is represented by a few species in California and doubtful records from Florida. 10. LARCA Chamberlin Larca Chamberlin (1930, p. 609). Genotype, by original designation: Garypus latiis Hansen. This genus, fig. 26, contains species in which the arolia are longer than the terminal Fig. 26. — Larca i/ranulala. An example of the suborder Diplosphyronida and the family Garypidae. The division of the tarsus into metatarsus and telotarsus is so obscure and weak that it is not discernible in the figure. 448 Illinois Natural History SuR\iiv Bulletin /'//. 24, An. 4 Fig. 27. — Lana granulala 9 . A, dorsal view of palp ; B, lateral view of chela ; C, dorsal view of carapace ; D, chelicera, mov- able finger. 0.185 mm. wide; chela exclusive of pedicle 0.85 mm. long, 0.247 mm. wide; depth of chelal hand 0.215 mm., length 0.44 mm.; movable chelal finger 0.44 mm. long. First leg with pars basalis 0.2.^5 mm. long, 0.09 mm. deep; pars tibialis 0.175 mm. long, 0.103 mm. deep; tibia 0.215 mm. long, 0.075 mm. deep; metatarsus 0.15 mm. long, 0.055 mm. deep; telotarsus 0.14 mm. long, 0.045 mm. deep. Fourth leg with entire femur 0.49 mm. long, 0.133 mm. deep; tibia 0.37 mm. long, 0.088 mm. deep; metatarsus 0.18 mm. long, 0.065 mm. deep; telotarsus 0.175 mm. long, 0.05 mm. deep. In the Illinois collections are several nymphs of two sizes. Since the determina- tion of which nymphal stages are represented is questionable, it is desirable to wait for descriptions until all three nymphal stages are available for study. Distribution.—This species occurs in the central and northeastern United States. No collections have been taken in Illinois in addition to those previously recorded (HoflE 19464) from Starved Rock State Park (La Salle County) and Fountain Blufif (Jackson County). The species is found chiefly in debris and moss on sandstone ledges. Illinois Records. — Fount.ain Bluff: March 18, 1942, Ross & Sanderson, 3 adults. Starved Rock St.ate Park: mossy debris on shelves, sandstone bluff, Nov. 8, 1943, Ross & Sanderson, 5 adults, 4 nymphs. Larca ffranulata (Banks). Chamberlin (1930, p. 616), Hoff (19+6/', p. 109). Chernes dentatus Ross (non Banks), (1944, fig. 56). Misidentification. Individuals of this species are easily recog- nized by the family characteristics, since this is the only garypid pseudoscorpion in the state. For sight recognition, the follow- ing characters are useful: the stout abdomen in which the width is nearly equal to the length, the triangular carapace, and the slender form of the palpal segments, fig. 27^. The following measurements are given for a more detailed check of identifications. They were taken from a female mounted in Canada balsam: body length 2.1 mm.; carapace 0.6 mm. long, 0.8 mm. wide across the posterior margin; abdomen 1.5 mm. long, 1.3 mm. wide; palpal trochanter 0.3 mm. long, 0.17 mm. wide; femur 0.66 mm. long, 0.163 mm. wide; tibia 0.57 mm. long. Fig. 28. — Psclapliochernes parvus. An ex- ample of the suborder Monosphyronida and the family Chernetidae. Ju,u. 1949 HoFF: PSEUDOSCORPIONS OF ILLINOIS 44V Suborder MONOSPHYRONIDA Pseudoscorpions of this suborder have only a single tarsal segment on each leg. Three superfamilies are recorded from America north of Mexico, only one of which is repre- sented in the north-central part of the United States. Kev to Si i'Erfamilies 1. With tour prominent eyes. . . Feaelloidea With two eyes or none, never with tour 2 2. Kemora ot legs I .ind II similar to those of legs III and IV, with the same type of articulation Cheiridioidea Kemora ot legs I and II each with a more or less distinct membranous articulation between pars basalis and pars tibialis, the apex ot the pars basalis often en- larged, and the less deep base of the pars tibialis frequently appears to fit int3 it, fig. 44./; femora of legs 111 and IV with pars basalis and tibialis more or less fused solidly, about the same length where they join, the tusion being a somewhat straight suture, tig. 44S. Cheliferoidea Superfamily FE.\ELLOIDEA The nearctic fauna of this superfamily contains only the family Pseudogarypidae, represented in North America by a single genus, Pseuiluijarypus EUingsen. This genus has only a few species and is restricted to the Rocky .Mountain and the Pacific Coast areas. Superfamily CHEIRIDIOIDE.\ Two families are represented in the fauna ot America north of Mexico, but neither is found in Illinois. Kev to Fa.milies Venom apparatus developed only in fixed chela! linger; femoral articulations of legs lacking or vestigial so that the pars tibialis and the pars basalis appear to be fused into one Cheiridiidae Venom apparatus developed in both chelal fingers; femoral articulations of legs well developed . . . Stemophoridae CHEIRIDIID.\E This family is represented in America north of Mexico by a few species of the genus Apocheiridium Chamberlin, found only on the west coast of the United States. STERNOPHORIDAE Representatives of this family are found in western Mexico, southern United States, and Australia (Chamberlin 1931(2). Two genera, one of which is of uncertain status, have been placed in the family. A limited number of species of the genus Simiofilinriis Chamberlin are known from southern and southwestern United States and one species of the genus Garyups Banks has been re- ported from Florida. The genus Garyops is inadequately described and Sternophortis may eventually prove to be a synonym. Superfamily GHELIFEROIDE.\ Members of this superfamily always have the femora of the first and fourth legs structurally dissimilar; eyes two or none. The group is represented in America north of Mexico by three families, two of which have representatives in our area. Kev to Families 1. .\t least a few accessory teeth pre.sent on chelal lingers, figs. 32D, 34fl, 36./; venom apparatus well developed in movable finger only, but may be present as a vestige in the fixed finger Cheriietidae, p. 44 in the pars tibialis, tibia 0.23-0.26 mm. ing, 0.065-0.077 mm. deep, length 3.35 to 55 times the depth; tarsus with flexor mar- in slightly convex, extensor margin nearly raight, setae more numerous than on other gments, setae varying from terminally and ibterminally denticulate on the basal part f the extensor surface to truly acuminate 1 the terminal portion of the segment ; irsus 0.2-1-0.27 mm. long, 0.05-0.054 mm. :ep, length 4.6 to 5.1 times the depth, ourth leg with chaetotaxy and sculpturing i in the first leg; trochanter with numerous ;tae, especially on the flexor surface, length ,16-0.17 mm., 1.35 to 1.45 times the depth; irs basalis subtriangular, distal three- jurths of flexor margin straight, flexor sur- ice with numerous long and subacuminate ;tae, length 0.16-0.175 mm., 1.3 to 1.45 mes the depth ; pars tibialis with extensor largin evenly and moderately convex, flexor largin straight and continuous with that of le pars basalis; pars tibialis 0.3-0.35 mm. ing, 0.122-0.15 mm. deep, length 2.3 to .45 times the depth; entire femur 0.42- .48 mm. long, length 3.2 to 3.45 times the epth ; tibia with weakly S-shaped extensor largin and convex flexor margin, length .5 to 3.85 times the depth; tarsus with both exor and extensor margins weakly convex, ightly narrowed distally, deepest near the :vel of the sensory seta, chaetotaxy much 5 in the tarsus of the first leg, 0.26-0.315 im. long, 0.065-0.07 mm. deep, length 4.4 4.0 in one individual) to 4.75 times the depth; sensory seta of the extensor surface of the tarsus located proximad from the mid-point of the segment, usually little more than 0.4 of the tarsus length from the prox- imal margin. Giiiiltil C.fimplrx.—Anterior operculum with about 20 setae arranged in a crescent; posterior operculum with 8 to 10 (rarely 12) marginal setae; four (rarely five or six) setae on the posterior lip of the genital open- ing, almost within the opening, and anteriad to the marginal row. I'EM.M.i:.—Females much more numerous than males. Female differing but little from male; slightly larger, up to 2.2 mm. or more in length, often a little more darkly pig- mented than the male. Carapace and abdo- men not distinctly different in the two sexes. Chiiuira.—Slightly larger and with the galea more branched than in the male ; other- wise almost identical in the two sexes. Palps.—Most segments, especially the chela, slightly larger than in the male; other- wise similar. Chela (measurements based on 16 Illinois specimens) exclusive of pedicle 0.85-0.95 mm. long, 0.27-0.31 mm. wide, length 2.9 to 3.15 (rarely less than 3.0) times the width; movable finger 0.45-0.51 mm. long. Teeth and tactile setae of chela as in the male; length-width ratios of chelae of Illinois specimens on the average slightly less than the ratios for the type specimens from Arkansas (Hoff 1945a). Li'ffs.—Shape, chaetotaxy, and sculptur- ing essentially as in the male ; segments, however, frequently larger; length-depth ratios about the same in the two sexes. The following measurements and ratios of cer- tain pedal segments in the female are based on measurements of nine individuals: tibia of first leg 0.255-0.295 mm. long, 0.072- 0.08 mm. deep, length 3.4 to 3.85 times the depth; tarsus of first leg 0.27-0.3 mm. long. 0.053-0.059 mm. deep, length 4.6 to 5.2 times the depth; pars tibialis of fourth leg 0.35- 0.4 mm. long, 0.135-0.155 mm. deep, length 2.45 to 2.75 times the depth; tibia of fourth leg 0.345-0.385 mm. long, 0.09-0.1 mm. deep, 3.7 to 4.2 times as long as deep. Genital Complex.—Anterior operculum with 14 to 18 setae; posterior operculum with 8 or 10 setae. Tritonymph.—Measurements are based on three individuals mounted in balsam. Much like the adult but smaller and lighter in color; appendages stouter. Body 1.35- 1.55 mm. long; carapace about 0.5 mm. long 404 Illinois Natural History Surnev Bulletin I'ol. 24, An. 4 and about 0.4 mm. wide ; abdomen between 0.6 and 0.7 mm. wide. Chelicera essentially as in the adult. Palpal segments conspicu- ously and coarsely granular on the flexor surfaces, other surfaces moderately granu- lar; chelal hand moderately granular; tro- chanter 0.22-0.23 mm. long, 0.13-0.14 mm. wide; femur with maximum length between 0.33 and 0.35 mm., length along the extensor margin 0.3-0.32 mm., width 0.14—0.15 mm., greatest length 2.3 to 2.5 times the width, length along the extensor margin 0.21 to 0.23 times the width ; tibia about 0.33 mm. long, 0.16 mm. wide; chela 0.61 ram. long, 0.205-0.21 mm. wide, length between 2.9 and 3.0 times the width; depth of chelal hand subequal to the width; chelal hand 0.32 mm. long; movable chelal finger 0.29-0.31 mm. long. Tactile setae of the chelal fingers much as in the adult except b is missing from the movable finger and isi is wanting from the fixed finger; also it is much closer to the level of est than to the level of et, while in the adult it is closer to the level of et than to the level of est. Marginal and accessory chelal teeth much as in the adult except fewer in number. Deutonymph.—Two specimens exam- ined. Smaller than the tritonymph but same general characteristics. Body length 1.0— 1.05 mm., carapace about 0.38 mm. long. Serrula exterior of the movable cheliceral finger with 14 or 15 ligulate plates. Palpal segments smaller than in the tritonymph but with about the same length-width ratios. Palp with the following measurements (based on two individuals) : trochanter about 0.17 mm. long, 0.1 mm. wide; femur with greatest length between 0.24 and 0.25 mm., width 0.11 mm.; tibia 0.23 to 0.24 mm. long, 0.12 mm. wide; chela exclusive of pedi- cle 0.45 to 0.46 mm. long, 0.148-0.155 mm. wide, length 2.9 to 3.1 times the width; chelal hand with length of 0.24 mm., depth about equal to the width ; movable chelal finger 0.22 mm. long. Movable chelal finger with two tactile setae: one, probably st, near the mid-point of the finger and the second, probably sh, near the proximal margin; nodus ramosus a little distad from st. Fixed chelal finger with tactile setae much as in the tritonymph but with both ist and one of the external series, probably esb, wanting. Accessory teeth of chelal fingers apparently wanting. Protonymph.—Somewhat smaller and with conspicuously stouter appendages than the deutonymph ; body length about 0.9 mm. Serrula exterior of the movable cheliceral finger apparently of 11 plates. Chela ex- clusive of pedicle about 0.4 mm. long, about 0.14 mm. wide; chelal hand exclusive of pedicle 0.21 mm. long; movable finger equal in length to length of hand exclusive of pedicle. Movable finger with one tactile seta, probably st, located about two-fifths of the finger length from the proximal finger margin. Fixed finger with one tactile seta, probably est, located somewhat distad from the mid-point of the finger and one basal seta of the external series located near the finger base; internal series represented by a single tactile seta located about on a level with the single basal seta of the external series. Distribution.-—Known only from Arkansas and Illinois; taken from scattered localities in all areas of the latter state. Habitat data are available for 25 collec- tions. Sixteen of these collections were made from rotting logs or hollow trees and, in two of these, nests of small mammals were pres- ent. The other collections were made from woody debris and ground cover. The col- lections indicate a decided association with retting wood as a preferred habitat. Illinois Records.—Thirty collections, taken throughout the year, are from Cache, Caledonia, Elk Grove, Elsah, Grand Tower, Harrisburg, Herod, Kampsville, Karnak, La Rue, Makanda, Monticello, Mount Olive, Pere Marquette State Park, Quincy, Sherman, Urbana. 15. DENDROCHERNES Beier Dendrocherties Beier (1932f, p. 171). Geno- type, monobasic: Oicrnes cyrneus L. Koch. Dendrochernes Beier. Hoff (1947, p. 536). Carapace almost quadrate or a little longer than wide, weakly to moderately granular, the posterior transverse furrow nearer to the posterior carapacic margin than to the median transverse furrow. Ter- gites except the eleventh divided, finely to moderately granular. Setae of the body and palps toothed, not appearing clavate. Flagel- lum of four setae. Palp heavy, fig. 35, finely to moderately granular; tactile seta ist is almost at the same level as est, st is nearer to sb than to t. Tarsus of fourth leg with a sensory seta distad from the mid- point of the segment. The genus is holarctic in distribution. In North America, Dendrochernes morosus •, 1949 Hoff: PsEunoscoRi'ioNs of Illinois 465 Fig. 35. — Dendroi hirnes mnrosus 9 . l")orsal ew of palp (setae omitted). Hanks) is recorded from Isle Royale, Lake iperior. 16. REGINACHERNES new genus Di.ACNOSls.—Cheliccra with fiagellum of lur setae; seta b of cheliceral hand acu- inate, sb stout and suhterminally denticu- te, tig. ibD ; subapical lobe of movable leliceral finger well developed, figs. 36£, 'C, finger-like, and conspicuous; galea out, with several simple terminal and sub- rminal rami. Palp stout; tactile seta st movable chelal finger midway between i and sb or somewhat closer to / than to sb, ist of fi.\ed chelal finger distad from est, figs. iiiA, ilB; setae of palp subclavate to clavate; little sexual dimorphism exhibited by palp; fi.xed chelal finger with reduced venedens and short vestigial venom duct, fig. ibB. Fourth leg with no true tactile seta on the tarsus, but with a denticulate pseudotactilc seta near the distal end. Seminal receptacle of the female in the form of a long and slender tubule with a terminal sac or bulb. Genotype. — Ri]ois Natural History Survey Bulletin lol. 24, Art. 4 Reginachernes ewingi new species Only two individuals, one male collected by Ewing more than 30 years ago, and one female, are available for study. Since the male is not in good condition for detailed examination, the female has been designated as the holotype fig. 36. The specimen col- lected by Ewing and deposited at the Muse- um of Comparative Zoology has, according to data accompanying the slide, been assigned successively to the species Chclanops rnoro- sus Banks and Chelanops sanborni (Hagen). The specimen appears to be more closely related to Hesperochernes sanborni as re- described by Hoff (1946fl) than to Dendro- chernes niorosus as also redescribed by Hoff (1947), but belongs to neither of these species. The present specimen appears not to have been reported by Ewing ( 1911 ) under either Chelanops morosus or sanborni, since the only specimens collected at Areola and as- signed by Ewing to the genus Chelanops were listed as Chelanops pallidas. It is pos- sible that this specimen was not included in the report made by Ewing in 1911. Female.—Body and appendages fairly stout; abdomen, carapace, and legs brown; palps deeper golden brown ; length of body about 2 mm. Carapace rounded anteriorly and laterally; surface coarsely granulate; anterior margin with 4 and the posterior margin with 8 to 10 setae; all carapacic setae distinctly clavate ; greatest width near the center of the carapace, slightly narrower behind; length of carapace 0.65 mm., great- est width 0.66 mm. (or a little less, as the carapace may be somewhat flattened from mounting) ; posterior width 0.64 mm. Ter- gites a little deeper brown than the cara- pace; interscutal areas subpapillose and not pigmented ; each tergal half with five to eight distinctly clavate setae. Sternites almost smooth, brown in color, all except the tenth divided and with scuta well sepa- rated; tergite 4 with nine setae; maximum number of setae on any sternal half is 10; all sternal setae acuminate. Pleural mem- branes with wavy, almost papillose, stria- tions; each anterior stigmatic plate with three setae, each posterior plate with two. Chelicera.—Yellow in color ; fairly stout ; palm of hand with netlike markings; longest flagellar seta serrate along almost the entire anterior edge. Fixed finger with two or three weak and rounded denticles on the inner margin of the apical tooth and two strong and one or two very weak denticles on the inner finger margin near the distal end; lamina exterior evenly convex. Mov- able finger stout, fig. 36£ ; subapical lobe located near the base of the apical tooth; galeal seta not reaching to the tip of the galea; galea fairly stout and straight, with apparently six simple rami in the distal half; scrrula exterior of 17 ligulate plates; mov- able finger about 0.16 mm. in length. Palp.—Fig. 36C Maxilla with numerous acuminate setae and with all except the ventral face moderately granulate; the tro- chanter, femur, and tibia weakly to moder- ately granular and with numerous clavate setae, the setae ranging from strongly cla- vate on the trochanter and femur to weakly clavate on the extensor surface of the tibia; chela weakly granulate on the flexor sur- face, setae more clavate on the flexor than on the extensor surface; fingers almost smooth and with numerous acuminate setae. Maxilla 0.34 mm. long, 0.24 mm. wide. Trochanter with very globose protuberances, little elevated; pedicle almost as long as wide ; 0.34 mm. long, 0.205 mm. wide. Femur with pedicle well separated from the rest of the segment and a little wider than long; flexor margin weakly convex except on the distal one-third; extensor margin a little convex; 0.48 mm. long, 0.21 mm. wide. Tibia with a stout pedicle; flexor margin bulging in the center but flattened beyond; extensor margin flatly convex in the central portion ; setae much less clavate on the ex- tensor than on the flexor surface; 0.48 mm. long, 0.22 mm. wide. Chela with pedicle near center of base; extensor margin flatly convex, flexor margin much more convex; fingers slender and gently curved; chela, without pedicle, 0.85 mm. long, 0.31 mm. wide; hand, without pedicle, 0.415 mm. long, 0.3 mm. deep ; movable finger 0.455 mm. long. Viewed laterally, fig. Z6A, chelal hand fairly stout, pedicle displaced a little to- ward the ventral side ; ventral margin little convex, dorsal margin more convex; basal margin rounded ; the fixed finger nearly straight, the movable finger a little curved. Tactile seta as shown in the figure. Fixed chelal finger with a reduced venedens, fig. 36S, and a short vestigial venom duct; nodus ramosus of movable finger between one and two areolar diameters basad from tactile seta /; marginal teeth of both fingers contiguous and cusp-bearing, between 30 and 35 in number; three or four internal une, 1949 Hoff: Pseudoscorpions of Illinois 467 id the same number of external accessory eth on each finger. Legs.—Setae of legs variable; those of the :tensor surface of segments chiefly clavate, hers subclavate to acuminate; segments )parently smooth. First leg with pars isalis 0.122 mm. deep; pars tibialis with )th margins evenly convex, 0.1 13 mm. deep; itire femur with most setae subclavate to avate, 0.34 mm. long; tibia stout and very eakly S-shaped. 0.247 mm. long, 0.087 mm. •ep ; tarsus with setae of extensor surface uminate, extensor margin nearly straight, •xor margin very weakly convex, deepest the basal third and tapering a little to- ard the distal end, 0.27 mm. long, 0.065 m. deep. Fourth leg with setae of the ochanter, the pars hasalis, and the flexor rface of the tarsus acuminate; setae of the tensor surface of the tibia and tarsus rongly clavate ; setae of the flexor surface the pars tibialis and tibia weakly clavate acuminate; pars basalis 0.145 mm. deep; tire femur with the flexor margin evenly id weakly convex, the extensor margin jll rounded and evenly convex, margins the two femoral parts continuous; entire mur 0.46 mm. long, 0.155 mm. deep; tibia uch more slender than that of the first I and a little S-shaped, 0.365 mm. long, )95 mm. deep; tarsus narrowing gradu- ly toward the distal end, 0.305 mm. long, )7 mm. deep ; a suhtactile clavate seta igcr than the other investing setae located tt'ard the distal end of the extensor margin the tarsus. Genital C.umplex.— Posterior margin with setae forming a single row; anterior erculum with about 20 setae irregularly ranged in a group anteriad to the genital erture. M.ALE.—The single known male, the allo- 3e, not in a favorable condition or position r study, having been mounted in an un- ssected condition by Ewing. As near as n be determined, structural details are ;ntical in the two sexes except that the da is a little stouter and the tactile seta of the movable chelal finger is relatively (ser to / and farther from sb in the male, easurements secured from the male as Hows: carapace 0.65 mm. long, 0.67 mm. de ; palpal trochanter 0.34 mm. long and 105 mm. wide; femur 0.49 mm. long. 0.21 n. wide; tibia 0.48 mm. long, 0.215 mm. de; chela exclusive of pedicle 0.85 mm. ig and 0.32 mm. wide; chelal hand ex- Fig. 37. — Reijina< hemes lymfliatus. A, dor- sal view of palp, holotype 9 ; B, lateral view of chelal hand, allotype i ; C, tip of movable cheliceral finger, holotype $ ; D, apical setae of extensor surface of tarsus IV', holotype 9. elusive of pedicle about 0.4 mm. long, mov- able finger 0.46 mm. long. Fourth leg with entire femur 0.46 mm. long, 0.15 mm. deep; tibia 0.36 mm. long, 0.09 mm. deep; tarsus 0.31 mm. long and 0.07 mm. deep. Details of genital complex not discernible in speci- men. Holotype, female.—.Muncie, Illinois, Sept. 19, 1943, H. H. Ross. Allotype, male.—Areola, Illinois, July 21, 1909, H. E. Ewing (.mcz). The holotype was collected from leaf mold and the allotype was secured from beneath the barLof an oak tree. Reghiachernes lyinphatus new species Reginaehernes tymphatus, figs. 37//-37Z), may be separated from ewingi by characters 468 Illinois Natural History Survey Bulletin Fol. 24, An. 4 given in the key. The palp of lympliatiis has considerable similarity to the palp of Chelanops corticis Ewing, as figured by Ewing (1911, fig. 9). Our form, however, differs in many ways from the text descrip- tion given by Ewing with respect to the cheliceral galea, the investing setae of the palps, and other details. There is a possi- bility that some of these characters may have been misinterpreted, in which case lymphatus may really be corticis. To date the type material of corticis has not been located ; so its identity cannot be established. Female.—Observations and measure- ments are based upon the female holotype and one female paratype unless otherwise indicated. Body and legs light brown, palps golden brown ; body stout ; length of body (four females measured) between 2.4 and 2.6 mm., the holotype with the abdomen contracted measuring only 1.95 mm. Cara- pace stout; anterior half with rounded mar- gins, posterior portion with sides almost parallel; surface moderately to coarsely granular, appearing more weakly granular on the dorsal surface; setae scattered, fairly numerous, distinctly clavate; posterior trans- verse furrow much closer to the posterior carapacic margin than to the median furrow; ' posterior carapacic margin with 10 to 12 clavate setae; eye spots not observed; length of carapace about 0.85 mm., greatest width about 0.75 mm. Tergites of abdomen brown in color, all divided e.xcept the eleventh, with the interscutal membranes very rugose; ter- gites fairly granular; setae clavate, usually seven setae on each scutum of first tergite and eight setae on each scutum of the second tergite, ma.ximum number of setae on any tergal half is 11. Sternites 4 through 10 divided; interscutal spaces striate and ru- gose; sternal scuta brown in color, marked by scalelike lines; each half-sternite of the fourth abdominal segment with four to six acuminate setae; maximum number of setae on any sternal half is 17. Pleural mem- branes very rugose; each anterior stigmatic plate with two setae, posterior plate with one; abdomen stout, usually about 1.5 mm. long, about 1 mm. wide. Chi'licerii.—Fairly stout ; palm of hand with netlike markings; subbasal seta with a few minute terminal and subterminal den- ticulations; longest flagellar seta unilaterally serrate, the serrations minute and widely spaced ; length of chelicera 0.22-0.24 mm., width of base 0.13 mm. Fixed finger slen- der; lamina exterior well developed and evenly convex; inner margin of apical tooth with three small denticles, inner margin of finger with two strong and two weak den- ticles near the distal end. Movable finger, fig. 37 C, fairly stout; subapical lobe inserted near the base of the apical tooth and much distad from the insertion of the galeal seta; one or two minute denticles on the inner finger margin near the level of the insertion of the galeal seta; galeal seta not reaching to the tip of the galea; galea fairly stout, with six simple and distally acute rami con- fined to the distal one-half of the galea; serrula exterior of 17 or 18 ligulate plates; length of movable cheliceral finger about 0.19 mm. Palp.—Fig. 37J. Measurements and ratios of the palpal femur, tibia, and chela (except the depth) given as the range of four individuals (the holotype and three female paratypes), of which two are in alco- hol. Stout, fairly deep brown to reddish or golden brown in color; the sides of the maxilla and the entire trochanter and femur moderately to coarsely granular; the flexor surface of the tibia moderately granular; the flexor surface of the chelal hand weakly to moderately granular; setae of the tro- chanter and the flexor surfaces of the femur and tibia heavy and chiefly clavate; setae of the extensor surface of the femur and tibia less strongly clavate and sometimes pauci- denticulate; setae of the flexor surface of the chelal hand subclavate, those of the extensor surface paucidenticulate ; setae of the fingers acuminate. Maxilla about 0.4 mm. long and 0.3 wide. Trochanter in strict dorsal view very stout; subdorsal protuber- ance rounded and not much elevated; tro- chanter of female paratype 0.42 mm. long, 0.24 mm. wide. Femur with pedicle little longer than wide; extensor margin of femur very flatly convex, flexor margin weakly convex in the basal two-thirds but weakly concave beyond ; measured along the ex- tensor margin 0.63-0.64 mm. long, 0.255- 0.27 mm. wide, length 2.35 to 2.5 times the width. Tibia with extensor margin slightly flattened in the central portion ; flexor mar- gin bulging and convex except at the extreme distal end where the margin is flattened or very slightly concave ; 0.6-0.63 mm. long, 0.28-0.29 mm. wide, length between 2.1 and 2.2 times the width. Chela with margins evenly convex, the flexor margin a little more convex than the extensor; base of hand June, 1949 Hokf: Pskuduscorhions ok Illinois 469 rounded; fingers fairly slender and sonie- uliat curved; chela, without pedicle, 0.99- 1.02 mm. long, 0.37-0.,?8 mm. wide, length be- tween 2.65 and 2.75 times the width ; chclal hand e.xclusive of pedicle 0.52-0.55 mm. long, about 0..S3 mm. deep (depth deter- mined for the hand of only one female) ; movable finger 0.5-0.53 mm. long. Viewed laterally, the base of the chelal hand appears rounded, the margins weakly convex, and the pedicle displaced a little toward the ventral side; the fixed finger nearly straight, the movable finger a little curved and ap- pearing weakly granulate on the exterior surface. Tactile setae of chelal fingers as shown for the male, fig. MB ; nodus ramo- sus of movable chelal finger varying from a position about midway between tactile setae / and st to a position much closer to St than to i. Each finger with about 40 contiguous, conical, cusp-bearing marginal teeth; accessory teeth somewhat variable, usually 8 to 10 in the external row of each finger and 1 to 4 in the internal row; end of fixed finger with a very poorly developed venedens containing a vestigial duct. Legs.—Measurements relative to the holotype are followed in parentheses by the corresponding measurements of the mounted female paratype whenever the two show a significant difference. Legs usually light brown in color ; femoral parts and tibiae weakly granular, granules not easily ob- served except on the pars tibialis; setae of the extensor surface of the segments and in part setae of flexor surfaces of femora subclavate to paucidenticulate ; setae of the flexor surfaces of the tibia and tarsus acuminate and more numerous. First leg with pars basalis 0.152 (0.16) mm. deep; pars tibialis 0.14 mm. deep; entire femur 0.44 mm. long, length 2.88 (2.75) times the depth; tibia stout, deepest near the distal one-third, 0.3 (0.315) mm. long, 0.102 mm. deep; tarsus tapering a little toward the distal end, subcylindrical, about 0.295 mm. long, 0.065 (0.068) mm. deep. Fourth leg with pars basalis 0.182 (0.175) mm. deep; pars tibialis 0.205 (0.192) mm. deep; femur with extensor margin evenly convex, flexor margin very weakly convex to straight, length of entire femur 0.595 (0.61) mm., length 2.9 (3.17) times the depth; tibia much more slender than in the first leg, flexor margin a little convex, extensor mar- gin straight to a very little concave ; tibia 0.46 (0.48) mm. long, 0.12 (0.114) mm. deep; tarsus subcylindrical but tapefing a little toward the distal end, 0.34 (0.35) mm. long, 0,084 mm. deep; the extensor mar- gin of the tarsus with a denticulate pseudo- tactile seta, fig. 37Z), longer than the den- ticulate investing setae and located 0.2-0.22 mm. from the proximal margin of the tarsus. Genital Complex.—About 12 to 15 mar- ginal setae on the posterior operculum; nearly 20 setae grouped anteriad to the aperture on the anterior operculum. Male.—Unless otherwise indicated, de- scription and measurements are based upon the male allotype. Body and carapace much as in the female ; a few more setae on the fourth sternal halves and a few less on the central sternal halves than in the female; body of allotype 2.4 mm. long, of one para- type 2.15 mm. long; carapace and abdomen as in the female. Chelicera.—As in the female. Palp.—Chaetotaxy and sculpturing, as well as the general appearance, much as in the opposite sex except setae may be a little heavier and the palpal femur and chela ap- pear to be a very little stouter. Measure- ments based on two individuals (one in alco- hol), the measurements of the male allotype followed in each instance by the correspond- ing measurement of the male paratype, when- ever a measurement was secured for the latter. Maxilla 0.38 mm. long, about 0.3 mm. wide; trochanter 0.43 mm. long, 0.25 mm. wide; femur measured along the ex- tensor margin 0.64 (0.6) mm. long, 0.27 (0.255) mm. wide; tibia 0.63 (0.6) mm. long, 0.295 (0.285) mm. wide; chela exclusive of pedicle 1.06 (0.97) mm. long, 0.407 (0.38) mm. wide; chelal hand exclusive of pedicle 0.55 (0.51) mm. long, 0.355 mm. deep; mov- able finger 0.545 (0.51) mm. long. Tactile setae, fig. 37/i, and teeth of the chelal fingers much as in the female. Legs.—Essentially as in the female; measurements secured only from the allo- type. First leg with pars basalis 0.15 mm. deep, pars tibialis 0.14 mm. deep; entire femur 0.44 mm. long; tibia 0.308 mm. long, 0.103 mm. deep; tarsus 0.285 mm. long, 0.065 mm. deep. Fourth leg with pars basalis 0.164 mm. deep, pars tibialis 0.183 mm. deep; entire femur 0.595 mm. long; tibia 0.465 mm. long, 0.1 18 mm. deep ; tarsus 0.345 mm. long, 0.084 mm. deep ; denticulate pseudotactile seta located 0.225 mm. from proximal margin of tarsus. Genital Complex.—Posterior operculum 470 Illinois Natural History Survey Bulletin I'ol. 24, Art. 4 with 24 scattered setae, some of which are arranjied along the posterior margin, and four smaller setae just posteriad to the pos- terior rim of the aperture; anterior opercu- lum with 24 scattered setae. Tritonymph.—Unless indicated to the contrary, description is based on one trito- nymph paratypc. Lighter in color, smaller in size, and with stouter segments than in the adult. Chaetotaxy of the abdomen and carapace much as in the adult but with a slightly smaller number of setae; body about 2 mm. long. Chelicera.—Much as in the adult except smaller; the denticulations of the subbasal seta almost wanting; galea more slender and the rami confined to about the distal one- third; serrula exterior of IS or 16 ligulate plates. Palp.—Chaetotaxy and sculpturing much as in the female, except the setae a little less stout, color lighter; the palpal femur a little stouter but the chela more slender than in the adult. Measurements of the femur, tibia, chela, and movable finger are the ranges secured from measuring three individuals, of which two are unmounted. Femur 0.4-0.41 mm. long, 0.195-0.2 mm. wide; tibia 0.395-0.4 mm. long, 0.205-0.21 mm. wide; chela exclusive of pedicle 0.7- 0.73 mm. long, 0.25-0.255 mm. wide; mov- able finger 0.37-0.39 mm. long; chelal hand exclusive of pedicle in the mounted paratype 0.37 mm. long, 0.35 mm. deep. Movable finger with three tactile setae: / a little more than one-third of the finger length from the tip; b placed much as in the adult; St midway between / and b; sb wanting; nodus ramosus about one areolar diameter proximad from the level of tactile seta t. Fixed finger with tactile setae much as in the adult except ist is wanting and it is relatively a little farther from the level of et. Each finger with between 25 and 30 marginal teeth; each external row of acces- sory teeth with three to five teeth, internal row represented by one or two teeth ; fixed finger with weakly developed venedens and vestigial duct. Lejis.—Lighter in color, less sclerotic, and with fewer setae than in the adult; segments stouter; tarsi more narrowed distally; fourth tarsus with the denticulate pseudo- tactile seta as described for the adult. Measurements not secured. Deutonymph.—Description based on one individual. Smaller, lighter in color, and with appendages stouter than in the trito- nymph ; most tergal scuta with five or six clavate setae ; anterior stigmatic plate ap- pears to have but one seta; length of body about 1.4 mm. Chelicera.—Smaller than in the trito- nymph; subbasal seta simple; galea with probably three rami, terminal and subter- ininal in position. Palp.—Segments much smaller, lighter in color, and with fewer and slightly weaker setae than in the tritonymph; general shape very similar in the tritonymph and the deuto- nymph. Measurements of one deutonymph follow: femur 0.28 mm. long, 0.145 mm, wide; tibia 0.28 mm. long, 0.15 mm. wide; chela exclusive of pedicle 0.53 mm. long, 0.185 mm. wide; chelal hand exclusive of pedicle 0.275 mm. long, 0.175 mm. deep; movable finger 0.27 mm. long. Viewed later- ally, dorsal margin of chelal hand appears much more convex than the ventral margin, Movable finger with two tactile setae; one, probably st, a little distad from the mid- point of the finger and about one areolar diameter proximad from the level of the nodus ramosus; b as in the tritonymph, Setae of the fixed finger considerably differ- ent from those of the tritonymph ; it near the mid-point of the finger or a little prox- imad from the mid-point; et about midway between the finger tip and it; est about as far from the finger base as et is from the finger tip; ib a little proximad from the level of isb ; esb apparently wanting ; eb basad from the level of ib. Marginal teeth of the chelal fingers much as in the tritonymph except cusps less well developed ; accessory teeth wanting except for a single internal accessory tooth near tip of fixed finger. Ler/s.—Much like the legs of the trito- nymph except less sclerotic, much smaller, and with many segments probably a little stouter. Pseudotactile seta of the fourth pedal tarsus denticulate in the mounted deutonymph. Holotype, female.—Urbana, Illinois: Brownfield Woods, Oct. 21, 1933, H. H. Ross. Allotype, male.—Mooseheart, Kane County, Illinois: Sept. 24, 1940, Henry Dybas (cm). Paratypes. — Illinois. Aurora: Sept. 4, 1939, Henry Dybas, 4 tritonymphs, 2 deuto- nymphs (cm) ; April, 1940, IS, 19,2 tri- tonymphs (cm). Mooseheart: same data as for allotype, 2? (cm). W4':i Hoff: Pseuuoscorpions of Illinois 471 The holotype was taken from soil-cover iiples in oaic-hickory woods. 17. PSEUDOZAONA Beier tuJozaonii Beier (1932(, p. 182; 1933, p. i42). Genotype, by original designation, also nonobasic: FsfuJozaontt tommitnij Beier. tuJozaona Beier. Hoff (1947, p. 539). Carapace lorifier than wide, with two insverse furrows. Setae of body and palps )thed, usually subclavate to clavate. agellum with four setae. Palps slender, s. iSJ, .^8(7, the pedicle of the femur not 11 set off from the rest of the segment. le tactile seta ist placed distad from ist the fixed chelal finger; st between / and or a little closer to / than to sb on the )vable chelal finger. Legs moderately nder; tarsus of fourth leg without a tac- e seta. This genus, which has not been reported )m Illinois, can be recognized by charac- istics given in the key. It contains the tjotype, communis, from Mexico; uni- 'mis (Banks), from Costa Rica; and rabilis (Banks), from the eastern United ates, where it has been taken from caves Kentucky and Virginia. Diagnostic char- acters are illustrated in figs. .^8/V-C'; a more nearly complete description has been given previously by the writer (Hoff 194b/). 18. DINOCHEIRUS Chamberlin Oinoi/ieinu Chamberlin (1929a, p. 171). (Jenotype, monobasic: Dinocheirus lenodi Chamberlin. Dinocheirus Chamberlin. Chanilierlin (1934, p. 126), Hoff (1947, p. 513). Dl.NCNOSls.—Carapace with two well- developed transverse furrows; usually no eye spots. Cheliceral hand with five setae, the basal seta acuminate, the subbasal seta subterminally denticulate; galea of male commonly less branched than the galea of the feinale; fiagellum of chelicera with four setae. Palps moderately stout ; chela of inale usually stouter and larger than that of the female; well-developed accessory teeth pres- ent on the chelal fingers; nodus ramosus of movable finger between / and sl\ st closer to / than to sb and / closer to st than to the finger tip; ist comnKmly a little dis- tad from est, fig. 39B. Tarsus of fourth leg with an acuminate or pseudotactile acumi- nate seta located distad from the mid-point of the extensor surface and longer than the Fi^. 38. — Pseudozaona mirabilis $ . A, palp, dorsal view. B, end of movable finger of clicera; C, chela, lateral view (teeth omitted). 472 Illinois Natural History Survey Bulletin lol. 24, Art. 4 depth of the tarsus. Seminal receptacle of on any sternal half about 12, usually some- the female paired, very elongate, tubular, what less; setae acuminate to subacuminate with a terminal ovate sac. and paucidenticulate. Pleural membranes Two species have been collected in Illinois. with fine wavy striations ; each stigmatic plate Several others are known from the Atlantic with one or two (rarely three) setae, some- states and from the West and Southwest. what variable; abdomen 1.65-1.8 mm. long, about two-thirds as wide as long. Key to Species CAc/iccra.—Fairly stout, deep yellow in Palpal femur with length more than 0.6 mm. ^^i^^. p^j^ ^^ ^^^^ ^j^j^ ^ f^^ ^^^^^^^ and more than 2.5 times the width , . , , ^ j ^- i ^ u i .... markings; subbasal seta denticulate, basal Palpal'femur with length less than 0.6 mm. ^eta acuminate; length of chelicera 0.24- and less than 2.5 times the width solus 0.25 mm., width of base 0.135-0.165 mm., movable finger 0.2-0.23 mm. long. Fixed Dinocheirus pallidus (Banks) new finger slender; two or three small denticles combination on the inner margin of the apical tooth and Chernes pallidus Banks (1890, p. 152). four or five denticles on the inner margin Hesperochernes pallidus (Banks). Hoff (1947, of the finger near the distal end. Movable p. 509). finger, fig. 39C, little curved; apical tooth Ewing (1911) listed Chelanops pallidus often weakly bicuspid ; subapical lobe weakly from Areola and from Marshall, Illinois. bicuspid or tricuspid, often a weak denticle A study of some of the specimens assigned on the finger margin near the insertion of by Ewing to this species indicates an incor- the galeal seta; gelea slender and with five rect determination, which is also evident or six acutely pointed, short rami confined when his figure (Ewing 1911, fig. 11) is to the distal one-third; galeal seta not compared with the lectotype of pallidus at reaching to the level of the tip of the galea ; the Museum of Comparative Zoology. serrula exterior of 17 or 18 ligulate plates. Ewing's available specimens of pallidus are Palp.—Fig. 39/^. Moderately stout; really Paracliernes squarrosus new species, granular except the face of the maxilla, the as noted under this latter species. extensor surface of the tibia and the chelal Diagnostic characters for pallidus are hand, and the fingers; setae of maxilla given in fig. 39. The male has not been de- acuminate; setae of the trochanter and scribed previously. Three specimens of this femur subclavate and multidenticulate, those sex were taken in an Arkansas collection of the tibia multidenticulate but somewhat along with a female that agrees closely with slender and especially on the extensor sur- the lectotype at the Museum of Comparative face not subclavate; setae of the chelal hand Zoology. weakly multidenticulate to paucidenticulate, Male.—Description and measurements those of the fingers acuminate. Maxilla based on four males, one from Illinois and 0.45-0.53 mm. long, 0.27-0.32 mm. wide, three from Arkansas. Body fairly stout. Trochanter with a stout subdorsal protuber- yellowish to light brown in color; palps ance ; length 0.38-0.45 mm., 1.4 to 1.6 times reddish-brown; body length 2.55-2.75 mm. the width. Femur with pedicle about as Carapace granular; setae clavate and fairly long as wide; extensor surface of femur numerous; anterior half of carapace weakly and somewhat flatly convex; flexor rounded, posterior portion of sides subpar- surface weakly convex except a little concave allel; posterior margin with 12 to 15 irregu- near the distal end; 0.77-0.88 mm. long, larly placed marginal setae; no eye spots; 0.27-0.31 mm. wide; length 2.75 to 3.25 carapace 0.88-0.96 mm. long, 0.6-0.8 mm. times the width. Tibia with extensor mar- wide near the center ; posterior width a little gin somewhat flatly convex; flexor margin less than the greatest width. Tergites of convex near the center but somewhat con- abdomen except the eleventh divided but first cave beyond; 0.76-0.8 mm. long, 0.29-0.34 tergite sometimes very weakly divided ; setae mm. wide; length 2.45 to 2.65 times the clavate; each first tergal scutum with 9 or 10 width. Chela as viewed from the dorsum setae, central tergal halves with as many with the extensor, flexor, and basal margins as 14 setae; tergal scuta moderately granu- more or less evenly convex; in general the lar. Sternites 4 through 10 divided, marked chelal hand is elongate-oval, tapering some- by scalelike markings; each half-sternite 4 what toward the base of the fingers, and with four setae; maximum number of setae widest in the basal half; chelal fingers Jmif. 1949 Hoff: Pseudoscori'ionj. or Illinois 473 slender, gently and evenly curved; chela exclusive of pedicle 1.22-1.36 mm. long, 0.43-0.52 mm. wide, length 2.6 to 3.0 times the width; chelal hand exclusive of pedicle Fig. 39. — Dinorlieirus paltidus i . .V, dorsal view of palp; B, lateral view of chela; (,', end of movable cheliceral finger. 0.64—0.69 mm. long, 0.4—0.52 mm. deep, usu- ally 4.5 mm. or less; movable finger between 0.63 and 0.72 mm. long, usually 0.7 mm. or more. Viewed laterally, fig. 39B. chelal hand fairly stout, extensor and flexor mar- gins moderately convex but hand tapering little toward base of fingers; basal margin flatly convex, with the pedicle displaced somewhat toward the ventral side; movable finger markedly convex, especially near the center; fixed finger variable, either nearly straight or with the inner margin convex and the outer margin distinctly concave; fingers gapping when closed. Tactile setae as shown in the figure. Fixed finger with a vestigial venedens and a short nonfunctional venom duct. Marginal teeth of chelal fin- gers contiguous and cuspid, between 35 and 45 on each finger; each finger usually with two (occasionally only one) to four internal and six to eight external accessory teeth. Nodus ramosus of movable chelal finger located between tactile seta / and si, usu- ally much closer to the latter than to the former. Legs.—Legs slender; setae multidenticu- late to paucidenticulate on the extensor sur- face of segments, paucidenticulate on the flexor surface of segments except acuminate on the flexor surface of the tarsi; femora and tibiae weakly granular or sculptured by netlike markings. First leg with tro- chanter 0.16-0.18 mm. long, length 1.1 to 1.13 times the width; pars basalis 0.16-0.18 mm. deep; pars tibialis 0.145-0.16 mm. deep, with both margins very weakly convex; en- tire femur 0.56-0.65 mm. long, length 3.1 to 3.6 times the depth; tibia slender, flexor margin weakly convex, 0.41-0.49 mm. long, 0.1-0.11 mm. deep, length 3.9 to 4.5 times the depth, length usually 4.3 or more times the depth; tarsus very slender, subcylindri- cal, tapering a little toward the distal end, 0.4-0.45 mm. long, 0.065-0.075 mm. deep, length 5.7 to 6.4 times the depth. Fourth leg with pars basalis 0.2-0.21 mm. deep; pars tibialis 0.23-0.24 mm. deep; entire femur with evenly convex extensor margin, flexor margin virtually straight except at the ends, 0.72-0.82 mm. long, length 3.0 to 3.4 times the depth ; tibia with weakly con- vex flexor margin, extensor margin nearly straight except at the basal end, 0.6-0.7 mm. long, 0.13-0.145 mm. deep, length 4.5 to 4.9 times the depth; tarsus tapering a little toward the distal end, 0.45-0.50 mm. long, 0.08-0.09 mm. deep, length 5.35 to 5.75 times the depth; short tactile seta on the extensor surface 0.32-0.37 mm. from the proximal end of the tarsus. Gfii'itdl (^onipli'x.—Posterior operculum with about 25 setae, many of which form an irregular marginal row, and with 6 to 8 setae along the very posterior rim of the aperture; anterior operculum very seta- ceous, with between 50 and 60 setae more or less scattered over the face of the oper- culum. Female.—The two available females, one from Illinois and one from Arkansas, are 474 Illinois Natural Ulstorv Survkv Bullktin lol. 24, .hi. 4 essentially like the male and also very simi- lar in detail to the female lectotype previ- ously described (Hoff 1947). Some of the minor discrepancies noticed between the present females and the lectotype can be attributed to the poorly preserved and somewhat broken condition of the lectotype. None of the differences are of sufficient value to justify even subspecific segregation. Measurements are given to show some of the species variations that occur. The measurement of the single available female from Illinois is followed in each instance by the corresponding measurement of the female from Arkansas. Female length 3.35 (2.98) mm.; carapace 1.1 (1.01) mm. long, 0.83 (0.675) mm. wide; abdomen about 2.3 (1.86) mm. long, 1.8 (1.25) mm. wide ; chelicera 0.26 (0.255) mm. long, 0.155 (0.145) mm. wide across the base, movable finger 0.21 (0.21) mm. long. Palp with maxilla 0.51 (0.51) mm. long, 0.35 (0.34) mm. wide; trochanter 0.51 (0.48) mm. long, 0.3 (0.32) mm. wide; femur measured along the extensor margin 0.88 (0.88) mm. long, greatest over-all length 0.94 (0.95) mm., width 0.305 (0.29) mm.; tibia 0.84 (0.785) mm. long, 0.335 (0.315) mm. wide; chela exclusive of pedicle 1.44 (1.44) mm. long, 0.52 (0.495) mm. wide; chelal hand ex- clusive of pedicle 0.75 (0.735) mm. long, 0.53 (0.485) mm. deep; movable finger 0.78 (0.77) mm. long. First leg with pars basalis 0.182 (0.178) mm. deep; pars tibialis 0.155 (0.152) mm. deep; entire femur 0.65 (0.625) mm. long; tibia 0.48 (0.465) mm. long, 0.106 (0.103) mm. deep; tarsus 0.45 (0.46) mm. long, 0.068 (0.076) mm. deep. Fourth leg with pars basalis 0.228 (0.225) mm. deep; pars tibialis 0.25 (0.246) mm. deep; entire femur 0.85 (0.83) mm. long; tibia 0.68 (0.69) mm. long, 0.136 (0.133) mm. deep; tarsus 0.49 (0.495) mm. long, 0.091 (0.092) mm. deep; tactile seta 0.34 (0.38) mm. from the proximal margin of the tarsus. Tritony.mph.—Very similar in most ways to the adult but lighter in color, much smaller in size, and with some segments, especially those of the legs, stouter. Mov- able chelal finger with three tactile setae: h (or jA?) wanting; / a little distad from the mid-point of the finger; st about as far from the finger base as t is from the tip; sb (or i?) as in the adult; nodus ramosus a little proximad from the level of tactile seta t. Fixed finger with tactile setae much as in the adult except isl is wanting. Im- portant measurements of the tritonyniph are given here. Body about 2.45 mm. long; carapace 0.78 mm. long, 0.58 mm. wide. Chelicera 0.22 mm. long, 0.13 wide; mov- able finger 0.175 mm. long. Palp with the trochanter 0.32 mm. long, 0.21 mm. wide femur 0.59 mm. long, 0.225 mm. wide tibia 0.55 mm. long, 0.25 mm. wide; cheh exclusive of peflicle 1.03 mm. long, 0.34! mm. wide ; chelal hand exclusive of pedich 0.53 mm. long, 0.35 mm. deep; movable finger 0.54 mm. long. First leg with entiri femur 0.43 mm. long, depth across pan basalis 0.152 mm.; tibia 0.308 mm. long 0.087 mm. deep ; tarsus 0.34 mm. long, 0.06! mm. deep. Fourth leg with entire femu] 0.61 mm. long, 0.192 mm. deep across thi pars tibialis; tibia 0.48 mm. long, 0.114 mm deep ; tarsus 0.38 mm. long, 0.084 mm. deep Distribution.—This species, originall; described from Ithaca, New York, has bcci taken in two collections from northern Illi nois. In addition, three males, one female and one tritonymph were secured by M. W Sanderson on April 13, 1940, at Lake Wed ington Wildlife Area, Washington County Arkansas. The Illinois collection from Magnoli; came from a decayed log, and the Arkansa specimens were taken from debris in a hoi low tree on a wooded hillside. Illinois Records.—^A single male wa taken in a collection made by Henry Dyba at Palos Park, Cook County, Illinois, oi May 16, 1943, and a single female wa taken at Magnolia, Putnam County, Illinois on March 23, 1944, by H. H. Ross. Dinocheirus solus new species Specimens of Dinocheirus solus, figs. 40,^ 40B, differ from those of many species of th genus Dinocheirus by their much smalle size. This new species appears to be close! related by size and general structure ti (lorsalis (Banks), from which it is readil; separated by small differences in the shap of some of the palpal segments, the lengtl and position of the tactile seta of the fourtl pedal tarsus, and numerous other details. Male.—Body ovate, fairly stout; yellov to yellowish-brown in color, with the palp a deeper golden brown ; length of body 2. mm. Carapace rounded anteriorly, side convex; widest across the center; furrow well marked; eyes apparently wanting; pos tcrior carapacic margin with 12 setae; al ne, 1949 Hoff: Pseui>oscorpions of Illinois 475 le of carapace weakly to strongly clavate; :s of carapace moderately granular, dor- face virtually smooth: length of carapace ? mm., greatest width 0.7 mm., posterior th 0.66 mm. Tergites of abdomen weakly nular and with scalelike markings, all ided e.xcept the last; intertergal spaces le; setae of tergites clavate and with as ny as 12 setae on some of the central ;al halves. Sternites 4 to 10 inclusive ided; fourth sternal halves each with r or five setae, central sternal halves each h 11 or 12 setae; all setae of sternites minate; sternites with scalelike sculptur- ; pleural membranes striated and rugose; lomen about 1.35 mm. long. 1.12 mm. le. llielicera.—Base fairly stout, fingers rela- •\y slender and slightly curved; subbasal I subterminally denticulate, basal seta nnnate ; length of chelicera 0.2 mm., Ith of base 0.125 mm. Fixed finger a le curved, with five or six weakly de- nped teeth on the distal inner margin in lition to three denticles on the inner sur- e of the apical tooth. Movable finger irly straight; subapical lobe not especially II developed; apical tooth terminally :rotic and bicuspid; galea slender and g, with live weakly developed and short niinal and subterminal rami; serrula eriiir of 17 to 18 plates; movable finger 75 mm. long. °alp.—Fig. 40/-/. Fairly stout; the lateral face of the maxilla, the extensor surface the trochanter, and the flexor surfaces the femur and tibia coarsely to moder- ly granular; other surfaces very weakly inulate to smooth ; setae acuminate on ' maxilla; setae of the trochanter, femur. 1 tibia somewhat stout and niultidenticu- e to paucidenticulate ; setae stouter on ' femur and the trochanter than else- ere; chelal hand with setae chiefly pauci- uiculate; acuminate setae on the fingers, axilla 0..?7 mm. long, 0.27 mm. wide, ochanter with the fle.xor, or inner margin, derately convex; 0..32 long, 0.21 mm. \t. Femur moderately stout to stout, 6 mm. long, 0.2.?5 mm. wide; outer mar- convex, more convex near the ends than the center; inner margin weakly convex the basal two-thirds but a little concave the distal one-third; the pedicle about as ig as wide, well set off from the rest of • segment. Tibia with outer margin flatly mded, inner margin bulging, but slightly concave distad from the center; pedicle stout ; 0.56 mm. long, 0.245 mm. wide. Chela with outer and inner margins more or less evenly convex, the outer a little less convex than the inner; pedicle near the center of the base; fingers slender, curved, well set off from hand; chela, pedicle excluded, 0.9 mm. Fig. 40. — Dinodieiius solus, holotype i . A, dorsal view of palp; B, lateral view of chela. long, 031 mm. wide; chelal hand 0.495 mm. long, 0..?4 mm. deep; movable finger of chela 0.46 mm. long. From the side, hand, fig. 40/J, appears somewhat quadrangular in gen- eral outline; pedicle displaced far toward the ventral side; ventral margin weakly convex, dorsal margin more convex; fingers moder- ately stout, the fixed finger nearly straight, the movable finger gently curved. Each fin- ger with about 40 marginal teeth, conical and with well-developed cusps at the distal end of the row but rounded and acuspid at the proximal end of the row; each finger with five external accessory teeth; movable finger with three, fixed finger with two, internal accessory teeth. Nodus ramosus of movable finger located just distad from the level of tactile seta st. Fixed finger with a vestigial venedens and a short vestigial venom duct. Legs.—Somewhat slender; yellow in color; pars tibialis and flexor surface of tibia of first leg weakly granular, otherwise pedal segments smooth; setae of the extensor sur- face of most segments paucidenticulate, slender, not clavate; setae of the flexor sur- 476 Illinois Natural History Survey Bulletin I'ol. 24, Art. face of segments chieflj' acuminate. First leg with pars basalis 0.133 mm. deep; pars tibialis with both margins evenly convex, 0.114 mm. deep; entire femur 0.43 mm. long, 0.133 mm. deep; tibia with outer mar- gin distinctly but weaicly S-shaped, flexor 43 G\ Fig. 41. — Hesperoc hemes caniidetisis (J. Dorsal view of palp. Fig. 42. — Hesperoehernes sanburni $ . Chela, lateral view (teeth omitted). Fig. 43. — Hesperoehernes sanborni i . Tip of movable finger of chclicera; . Cahokia: "50" on cork, Aug. 6, 194.<, . Snow, 19 (ws). H.'WANA: debris and St in log. Nov. 9, 1943, Ross & Sanderson. } ; ground cover below levee near river, 3V. 9, 194.^ Ross & Sanderson, 1 9 . ERRIN : July 24, 1944, W. Snow, 1 9 (ws). vmpsville: leafy and woody debris on hill- le, Sept. 30, 1943, Ross & Sanderson, 1 i . Narca: fungus in tree hole, July 22, 1943, . H. Ross, 29. Quincy: near Burton's ive, mouse nest and dead wood in hollow ag. April 27, 1944, C. Hoff, \$ (ch). *bana: in rotten log, March 29, 1942, H. . Ross, 1 9 ; tree hole, .Nov. 12, 1944, W. ow. 1 9 (ws) ; University Woods, stom- tl of red-bellied woodpecker, Nov. 12-13, 34, A. C. Touniey, 1 9 (hjv). White EATH : "ex-fungi," Aug. 5, 1939, Ross & egel, 2 9 . 22. ILLINICHERNES new genus Dlagnosis.—C'helicera with flagellum of ur setae; basal seta of cheliceral hand uminate, subbasal seta denticulate. Palps irly stout ; setae, figs. 46C-46£, of palps d more especially of dorsum of body bi- terally feathered, leaf like, and stout; tae of sternal scuta chiefly clavate; prox- lal two-thirds of fixed chelal finger, fig. 46/i, bearing long clavate setae; tactile seta si of movable chelal finger closer to / than to sb; ist considerably distad from est on fixed chelal finger; both ib and isb distad from the level of esb; palps showing little sexual dimorphism. Tarsus of fourth leg without a tactile seta. Seminal receptacle of female not observed. Genotype. — lUiniihernis ilistinctus new species. This genus appears closely related to the genus Hesperocheriits Chamberlin, from which it may be separated without difficulty by the nature of the setae of the body and palps and the acuminate condition of the basal seta of the cheliceral hand. Only one species is known in the genus. Illiiiichernes distinclus new species This species is the only one kno«n in the genus; hence, the diagnostic features of the genus are also the diagnostic features of the species. Several diagnostic structures are illustrated in fig. 46. Male.—Description based on three males, including the holotype. Measurements are given as the limits of range. Body stout ; palps and legs moderately stout; body and legs light brown; palps deep reddish-brown or golden in color; body 1.7-1.85 mm. long. Carapace with anterior half rounded, later- al margins convex; surface coarsely granu- lar; setae stout, wide, and feather-like in general appearance; no eye spots; median Fig. A6.—lllinir/i,rnrs distinctiis, holotype i. A, dorsal view of palp; li, lateral view chela; C, a seta of the palpal femur; D, another seta of the palpal femur; E, side view of a la from the palpal femur. 482 Illinois Natural Histoky Survey Bulletin Jol. 24, Art. transverse furrow a little posteriad to or near the center of the carapace, posterior furrow much nearer to the posterior cara- pacic margin than to the median furrow; 12 to 14 setae along the posterior margin uf the carapace ; length of carapace 0.65-0.72 mm., greatest width near the center and equal to 0.62-0.65 mm. ; posterior width very slightly less than the greatest width. Abdomen oval, very stout; tergites except the eleventh divided; surface of tergites granular; interscutal spaces not especially wide, usually narrow ; each scutum of first tergite with six to eight setae; maxi- mum number of setae on any tergite is about 11; all tergal setae stout and clavate, like those of the carapace. Sternites 4 to 10 divided, interscutal spaces narrow and stri- ate; setae of sternal halves varying from subacuminate on the anterior part of the abdomen to strongly clavate on the central and posterior portions; each fourth sternal scutum with 5 or 6 setae, maximum num- ber on central sternites about 10; surface of sternal scuta with scalelike markings. Each anterior stigmatic plate with two or three small acuminate setae, each posterior plate with three. Pleural membranes very rugose and irregularly striate; length of abdomen 1.05-1.13 mm., width about 0.95-1.02 mm. Chelicera.—Yellow in color; fairly stout; exterior surface of base marked by weakly developed netlike lines; subbasal seta with three or four terminal and subterminal spi- nules; basal seta smaller and acuminate; largest flagellar seta unilaterally serrate along the distal half; the two smaller flagel- lar setae subequal in length; chelicera about 0.19 mm. long and with the base 0.12 mm. wide; length of movable finger between 0.145 and 0.165 mm. Fixed finger slender; three small rounded teeth on the inner surface of the apical tooth followed by four (of which the basal two are weak) denticles along the inner finger margin. Movable finger with a long and slender apical tooth, subapical lobe moderately well developed but much shorter than the apical tooth ; galeal seta reaching about to the level of the tip of the galea; galea straight and with two or three very minute denticles (often not dis- cernible) confined to the distal one-third of the galea; serrula exterior consisting of 15 or 16 ligulate plates. Falp.—Fig. 46^. Coarsely granular ex- cept on the chelal fingers; most setae of maxilla weakly clavate, with numerous den- ticulations; setae of trochanter, femur, tibij and chelal hand clavate, stout, very simila to those of the carapace and tergites; fixei finger with long clavate setae on the dorsa and extensor surfaces of more than the basa one-half of the finger, setae of the remain der of the fixed finger and the entire mov able finger acuminate. Maxilla 0.33-0.3 mm. long, 0.25-0.26 mm. wide. Trochante with well-defined pedicle about as long a wide; subspherical in shape beyond th pedicle; sublateral and subdorsal protuber ances rounded and not much elevated thickly set with setae on the flexor surfac but very few setae on the extensor surface trochanter 0.32-0.385 mm. long, about 0.21 0.242 mm. wide, length 1.5 to 1.6 times th width. Femur with a well-defined pedicl about as long as wide; femur subcylindrica beyond the pedicle except near the dista end; extensor margin flatly convex in th central part, a little more convex beyond flexor margin very weakly convex in th central part and very weakly concave in th distal one-third or one-fourth; 0.6-0.69 mm long, 0.21-0.225 mm. wide, length 2.85 t 3.05 times the width. Tibia pedicellate extensor margin flatly convex in the centra part but a little more convex near each end flexor margin centrally rounded and some what bulging, flattened or very little concav in the distal part; tibia 0.57-0.63 mm. long 0.225-0.25 mm. wide, length 2.5 to 2.5 times the width. Chela with both extenso and flexor margins of hand gently am evenly rounded; pedicle placed slightly to ward the extensor margin; fingers relativel; stout, slightly curved, and tapering gradu ally toward the distal end ; chela exclusiv of pedicle 0.84-0.955 mm. long, 0.34-0.36 mm. wide, length 2.45 to 2.6 times th' v.'idth ; chelal hand without pedicle 0.44- 0.49 mm. long, 0.32-0.375 mm. deep; lengtl of movable chelal finger 0.42-0.48 mm From the side, chela, fig. 465, fairly stout pedicle displaced conspicuously toward thi ventral side; ventral margin a little les convex than the dorsal margin; fixed finge: stout and straight, tapering regularly to ward the distal end; movable finger curvec and more slender than the opposing finger Movable finger with nodus ramosus betweei one and two areolar diameters basad fron the level of tactile seta st. Tactile setai placed as shown in the figure. Margina teeth of chelal fingers contiguous, and, eX' cept for a few proximal teeth, cusp-bearing ««,-, 1949 HoFF: PSEUDOSCORPIONS OF ILLINOIS 483 sually between 30 and 35 marginal teeth n each finger; movable finger usually with 3ur or five external and one or two internal ccessory teeth ; fixed finger with seven or ight external and two or three internal ccessory teeth. Vestigial venedens and dort venom duct on fixed finger. Legs.—Moderately slender; most seg- lents except the tarsi sculptured by scale- ke to granular markings; all setae except few on the distal portion of the tarsi lultidenticulate and clavate to subclavate. irst leg with pars basalis 0.13-0.14 mm. eep ; pars tibialis slender, extensor margin little convex, flexor margin less convex to Imost straight. 0.11-0.12 mm. deep; entire ;mur 0.42-0.47 mm. long, length 3.2 to .35 times the depth ; tibia with flexor mar- in a little convex, extensor margin very eakly concave in the distal two-thirds, .32-6.35 mm. long, 0.08-0.086 mm. deep, ;ngth 3.95 to 4.1 times the depth; tarsus ith the extensor margin almost straight, exor margin a little convex, tapering some- hat toward the distal end, 0.34—0.38 mm. jng. 0.058-0.064 mm. deep, length 5.85 to .4 times the depth. Fourth leg with the ars basalis 0.135-0.148 mm. deep; pars Ibialis 0.145-0.159 mm. deep; entire femur airly slender, extensor margin evenly con- ex, flexor margin nearly straight, 0.51- .595 mm. long, length 3.45 to 3.8 times be depth ; tibia weakly S-shaped. 0.43-0.48 im. long. 0.09-0.1 mm. deep, length 4.6 3 4.9 times the depth; tarsus with both margins slightly convex, tapering in the dis- il one-half, 0.37-0.4 mm. long, 0.07-0.072 im. deep, length 5.3 to 5.6 times the depth. Genital Complex.—Anterior operculum lith usually between 35 and 40 acuminate nd well-developed setae; posterior oper- ulum with four to six multidenticulate etae along the posterior margin, with a Dtal of about 20 setae on the operculum. Fem.ale.—Measurements and ratios given re the ranges of three females, the allo- tpe and two paratypes. Essentially like he male; body 1.95-2.05 mm. in length. arapace with 14 to 16 marginal setae, .72-0.79 mm. long, greatest width 0.61- .69 mm., posterior width little less than he greatest width. Abdomen 1.1.5-1.3 mm. :)ng, 1.05-1.2 mm. wide. Chelicera.—Chiefly as in the male except he galea with five terminal and subterminal ami, each minute and simple, but much nore highly developed and conspicuous than in the male ; galeal seta not extending to the tip of the galea; serrula exterior of 16 to 17 plates; chelicera 0.21-0.22 mm. long, base 0.112-0.117 mm. wide, movable finger 0.15-0.155 mm. long. I'alfi.—X'irtually like that of the male. Maxilla 0.35-0.38 mm. long, 0.24-0.26 mm. wide, length 1.43 to 1.48 times the width; trochanter 0.36-0.39 mm. long, 0.22-0.24 mm. wide, length 1.58 to 1.6 times the width; femur measured along the extensor margin 0.64-0.73 mm. long, 0.21-0.225 mm. wide, length 2.97 to 3.22 times the width; tibia 0.58-0.66 mm. long, 0.225-0.25 mm. wide, length 2.43 to 2.64 times the width ; chela exclusive of pedicle 0.88-0.975 mm. long, 0.325-0.37 mm. wide, length 2.55 to 2.7 times the width; hand of chela without pedicle 0.45-0.5 mm. long, 0.325-0.37 mm. deep; movable chelal finger 0.45-0.51 mm. in length. Tactile setae and teeth of chelal fingers as in the male. Legs.—As in the male. First leg with pars basalis 0.133-0.143 mm. deep; pars tibialis 0.11-0.12 mm. deep; entire femur 0.44—0.51 mm. long, length 3.22 to 3.6 times the depth ; tibia 0.34-0.38 mm. long. 0.085-0.09 mm. deep, length 3.92 to 4.22 times the depth ; tarsus 0.35-0.38 mm. long, 0.065-0.07 mm. deep, length 5.0 to 5.6 times the depth. Fourth leg with pars basalis 0.137-0.152 mm. deep; pars tibialis 0.145-0.158 mm. deep; entire femur 0.56-0.64 mm. long, 3.65 to 4.05 times the depth; tibia 0.45-0.51 mm. long, 0.092-0.103 mm. deep, length 4.65 to 4.95 times the depth; tibia 0.39-0.42 mm. long, 0.069-0.076 mm. deep, length 5.3 to 5.8 times the depth. Genital Complex.—Anterior operculum with 30 to 35 scattered setae; posterior operculum with 13 to 15 setae arranged in a single marginal row along the posterior margin of the operculum. Tritonv.mph.—Observations and meas- urements based on three individuals. Body and appendages with color, sculpturing, and chaetotaxy much as in the adult; body 1.25- 1.45 mm. long. Carapace usually with 10 to 12 setae along the posterior carapacic mar- gin; carapace about 0.6 mm. long, 0.52 mm. wide. Tergites less sclerotic than in the adult; each first tergal scutum with five or six setae, central scuta with no more than eight setae. Sternites faintly sculptured, without color, weakly sclerotized ; setae as in the adult, four or five setae on each fourth half-sternite, central sternal halves 484 Illinois Natural History Survey Bulletin Jol. 24, Art. 4 with no more than six setae. Each stigmatic plate with two setae ; abdomen 0.69-0.84 mm. long, 0.72-0.77 mm. wide. Chelicera.—Like that of the female in all details including the nature of the galea, but smaller and less sclerotic. Chelicera 0.175-0.19 mm. long, base about 0.1 mm. wide; movable finger 0.13-0.135 mm. long; scrrula exterior of 14 ligulate plates. Palp.—Essentially like that of the male except the segments are smaller; the femur and tibia, especially the pedicles, are rela- tively stouter while the chela is a little more slender; the palps are a little lighter in color than in the male. Palps with maxilla 0.27- 0.29 mm. long, 0.185-0.2 mm. wide, length about 1.45 times the width; trochanter about 0.285 mm. long, 0.17-0.18 mm. wide; femur measured along the extensor margin 0.45-0.47 mm. long, 0.16-0.17 mm. wide, length 2.75 to 2.85 times the width; tibia 0.42-0.45 mm. long, 0.175-0.185 mm. wide, length 2.4 to 2.45 times the width; chela exclusive of pedicle 0.66-0.68 mm. long, 0.245-0.25 mm. wide, length between 2.65 and 2.8 times the width; chelal hand with- out pedicle 0.33-0.34 mm. long, 0.24 mm. deep; movable finger 0.34—0.35 mm. long. From the side, the chelal hand appears less stout than that in the adult. Movable finger with three tactile setae: t about one- third of the finger length from the tip; st in the basal half of the finger and very little closer to 1 than to sb; sb between one-fourth and one-fifth of the finger length from the hand margin; b wanting; nodus ramosus about midway between / and st. Fixed finger with tactile setae much as in the adult except seta ist is wanting. About 25 or 30 marginal teeth on each finger; some- what fewer accessory teeth than in the adult. Legs.—Lighter in color, somewhat less sclerotic, smaller, and a little stouter than in the adult; surface of segments virtually without sculpturing; setae as in the adult. First leg with segments shaped much as in the adult except that the tibia and the tarsus are much stouter and the tarsus narrows more rapidly toward the distal end; entire femur 0.33-0.35 mm. long, length 3.1 to 3.2 times the depth; tibia 0.24 mm. long, 0.072-0.076 mm. deep, length 3.15 to 3.35 times the depth; tarsus 0.26-0.28 mm. long, 0.06-0.061 mm. deep, length 4.35 to 4.7 times the depth. Fourth leg much like that of the male; the flexor margin of the tibia evenly but weakly convex, the extensor mar- gin virtually straight to a little concave in the distal two-thirds; the tarsus tapering markedly in the distal one-half; pars tibialis 0.114—0.122 mm. deep; entire femur 0.41- 0.42 mm. long, length 3.45 to 3.6 times the depth; tibia 0.32-0.33 mm. long, 0.08-0.085 mm. deep, length 3.8 to 4. 15 times the depth ; tarsus 0.29-0.31 mm. long, 0.064-0.065 mm. deep, length 4.55 to 4.8 times the depth. Protonymph.—Description based on two individuals; measurements of one are given in parentheses after the measurements of the other whenever the two difter. Body stout; lighter in color than the adult; length 1.02 (0.94) mm. Setae of body, legs, and palps like those of the adult except much less numerous. Ten or 11 plates on the serrula exterior of the movable cheliceral finger. Palps much lighter in color than in the adult; surface of trochanter and femur granular, surfaces of tibia and chela slightly granulate or smooth; clavate setae on the side of the fixed chelal finger as in the adult. Palpal segments smaller and, with the ex- ception of the chela, much stouter than in the tritonymph. Palpal femur 0.2 (0.21) mm. long, 0.095 mm. wide ; tibia 0.2 mm. long, 0.105 (0.1) mm. wide; chela 0.39 (0.40) mm. long exclusive of pedicle, about 0.135 mm. wide; chela 0.135 mm. deep: hand exclusive of pedicle 0.2 (0.19) mm. long; movable finger 0.205 mm. long. Each chelal finger with between 15 and 20 mar- ginal teeth, chiefly acuspid ; no accessory teeth observed. Movable finger with one tactile seta {tf) near the center of the finger. Three setae on the fixed finger ; two are external, one about one-third of the finger length from the tip and the other near the base; one is internal, located between one- third of the finger length from the base and the mid-point of the finger. Holotype, male.—Magnolia, Illinois: decayed log, March 23, 1944, H. H. Ross. Allotype, female.—Same data as for holotype. Paratype. — Illinois.—Kell: March 7, 1945, Ross & Sanderson, 2 tcrii North America. Macmillaii Company, N. V. 1035 pp. 766 tigs. Ewing. H. E. 1911. Notes on pseudoscorpions; a study on the variations of our common species, CItelijcr cancroides. Linn., with systematic notes on other species. N. Y. Em. Soc. Jour. 19:65-81. 15 figs. Feio, Jose Lacerda de Araujo 1941. Sobre um curioso pseudoscopiao. Papeis avulsos do Departmento de Zoologia l:241-f. 1 fig. San Paulo. Fourcroy, Antoine Francois 1785. Emomologia parisiensis. 2 vols., 554 pp. Paris. Geoffroy, E. L. 1762. Histoire abregee des insectes (jui se trouveiit aux environs ile Paris. 2 vols.: 28 + 523 pp., 10 pis. ; 690 pp., 12 pis. Paris. Gervais, Francois Louis Paul 1849. In Gay Historia fisica y politica de Chile (Zoologica) 4:13. Paris. Hadzi, Jovan 1933a. Primos poznavanju pseudoskorpijske fauiie Primorja. Prirodoslovna istrazivanja Kraljevine Jugoslavije 18:125—92. Zagreb. 1933/'. Beitrag zur Kenntnis der Pseudoskorpioneii—Fauna des Kiistenlandes. Academic Vougoslave, Classe des sciences mathematii)ue> et iiaturelles Bulletin International 27:173-99. Zagreb. Hansen. Hermann 1869. The -American Pseudo-scorpions. Record of .'\merican Entomology for the Year 1868: 48-52. Salem. 1879. Hohlen-Chelifer in Nord-.\merica. Zoologischer .\nzeiger 2:399-4(10. Leipzig. Hermann, J. F. 1804. Mcmoire apterologique. 144 pp., 9 col. pis. Strasbourg. Hoff. C. Clayton 1944((. Notes on three pseudoscorpions from Illinois. Hi. State -Acad. Sci. Trans. 37:123-8. 2 figs. 1944A. New pseudoscorpions of the subfamily Lamprochernetinae. Am. Mus. Nat. Hist. Novitates 1271:1-12. 15 figs. 1945rt. New species and records of pseudoscorpions from Arkansas. Am. Micros. Soc. Trans. 64:34-57. 2 pis. 21 figs. 1945/'. New species and records of cheliferid pseudoscorpions. Am. Midland Nat. 34:511—22. 12 figs. 1945(". Pseudoscorpions from North Carolina. Am. Micros. Soc. Trans. 64:311—27. 12 figs. 1945J. Hesperocherncs canadensis, a new chernetid pseudoscorpion from Canada. .•\m. Mus. Nat. Hist. Novitates 1273:1-4. 7 figs. 1945c. The pseudoscorpion genus Alhinrix Chamberlin. Am. Mus. Nat. Hist. Novitates 1277:1-12. 20 figs. 1946rt. A redescription of two of Hagen's pseudoscorpion species. New Eng. Zool. Club. Proc. 23:99-107. 6 text figs. PI. I with 10 figs. 1946i. Additional notes on pseudoscorpions from Illinois. III. State Acad. Sci. Trans. 38: 103-10. 1946<'. New pseudoscorpions, chiefly neotropical, of the suborder Monosphyronida. Am. Mus. Nat. Hist. Novitates 1318:1-32. 32 figs. 1946t/. The pseudoscorpion tribe Cheliferini. Chicago Acad. Sci. Bui. 7:485—90. 1946<'. American species of the pseudoscorpion genus Microhisnim Chamberlin, 1930. Chicago .Acad. Sci. Bui. 7:493-97. 1946/. A study of the type collections of some pseudoscorpions originallv tlescrlbed by- Nathan Banks. Wash. .Acad. Sci. Jour. 36(6) :195-205. 8 figs. 1947. The species of the pseudoscorpion genus i'.lwlanops described by Banks. Har\'ard Univ. Mus. Compar. Zool. Hul. 98:473-550. 37 figs. iew, H. W. 1912. On the pairing of pseudoscorpiones. Zool. Soc. London Proc. 376—90. ioch, C. L. 1843. Die Arachniden 10:37-80. Pis. 337-347. Niirnberg. Linnaeus, Carolus 1758. Systema naturae, tenth edition 1. 2 + 824 pp. Helmiae. 496 Illinois Natural History Survity Hulletin I'lil. 24. An. 4 Preyssler, J. D. E. 1790. V'erzeichniss bohmischer Insecten. 108 pp., 2 col. pis. Prague. Roewer, C. Fr. 1936- Cheloncthi otier Pseudoskoipione. /« Broiin, H. G., Die Klassen und Ordnungen 1937. des Tierreichs 5:div. 4, book 6, no. 2, 1-320. Leipzig. Ross, Herbert H. 19+4. How to collect and preserve insects. 111. Nat. Hist. Surv. Circ. 39:1-55. 63 figs. Say, Thomas 1821. An account of the Arachnides of the United States. Acad. Nat. Sci. Phila. Jour. 2:59-82. Simon, Eugene 1879. Chernetes. Les Arachnides de France 7:1-78. Paris. Stecker, Anton 1875. Ueber zweifelhafte Chernetiden-Arten, welche von A. Menge beschrieben wurdcn. Deutsche (Berliner) Entomologische Zeitschrift 19:305-14. Tomosvary, O. 1882. Pseudoscorpiones Faunae Hungariae. Matematikai es termeszettudomanyi Kozle- menyek 18:135-256. Budapest. Vachon, Max 1940. Remarques sur la phoresie des pseudoscorpiones. Societe entomologique de France Annales 109:1-18. Paris. 1941rt. Chthonius tetrachetaius P. et ses formes immatures (1" note). Museum national d'histoire naturelle Bui. 13:442-9. 23 figs. Paris. 1941//. Chlhniiius tetraihelatus P. et ses formes immatures (2" note). Museum national d'histoire naturelle Bui. 13:540-7. 6 figs. Paris. 1947. Nouvelles remarques a propos de la phoresie des pseudoscorpiones. Museum national d'histoire naturelle Bui. 19:84-7. Paris. INDEX The page entries in boldface type refer to the principal treatment of various categories from suborders to subspecies and varieties. Names that are synonyms, or of changed generic assignment, are indicateit by itaiu type. A D Acuminochernes, 455, 476 Oaclylochelifer, 486, 491 aflinis, Chelanops, 461 Dactylocheliferini, 428, 491 Albiorix, 444 l^endrochernes, 455, 464 Allochernes, 465 lienltilus, Chelanops, 478 Alura, 429 dt-titatus, Chelijer cancroides, 486, 487 Apocheiridium, 449 Ji-nlatus, Chnncs, 448, 478 .\pochthonius, 432, 434 dentatus, Mirochernes, 415, 418, 428, 478 .^temnidae, 417, 449, 485 Dinocheirus, 456, 471, 474 Diplosphyronida, 413, 426, 428, 443 B distinctus, lllinichernes, 418, 428, 481 dorsalis, Dinocheirus, 474 brunneum, Microbisium, 416, 418, 428, 445. 446 hrunneum, Ubisium, 444, 445 E Q, ellipticus, Lamprocherncs, 450 clongatus, Paratemnus, 485 nillus. Hysleroc/ielifir, 489 Ephippiochthonius, 433 callus, Paisochelifer, 416, 418, 428, 489 crosidens, Miimlochthoiiius, 436 lancroides, Ararus. 486 evvingi, Reginachernes, 418, 428, 465, 466, 467 cancroides, Chelifer, 414, 416, 418, 428, 486, 487, 488, 489 F carolinensis, Neobisium, 444 Cheiridiidae, -^9 Feaelloidea, 449 Cheiridioidea, 449 Chelanops, 455, 460, 461, 466 G Chelifer, 486 Chcliferidae, 426, 428, 449, 485, 493 Garypiiiae, 477 Cheliferinae, 426, 428, 485 CJarypoidea, 446 Cheliferini, 428, 486 Garypus, 415, 447, 449 Cheliferoidea, 449 gigas, Microcreagris, 444 Chernetidae, 426, 428, 449, 485 tiraminella, 188, 263 Chernetinae, 428, 450, 455, 485 granulata, Larca, 416, 418, 428, 447 Chitra, 444 t/ranulatus, Garypus, 447 Chthoniidae, 428, 429, 431 grossus, Lamprocherncs, 450 Chthoniinae, 428, 431 Chthoniini, 428, 431, 443 H Chthonius, 432. 433 chyzeri, Lamprocherncs, 453 Hesperochernes, 455, 465, 476, 481 coecus, Chelifer, 460 Helerochthonius, 432, 434 communis, Pseudozaona, 471 lletcrosphyronida, 413, 426, 428, 429 confusum, Microbisium, 415, 418, 428, 445, 446 Ilyarinus, 444 copiosus, Dactylochelifer, 415, 418, 428, 491 fortuis, Chelanops, 468, 494, 485 1 corticis, Chelanops (?), 418, 428 corticis, Cjcnus ?, 455, 484 Ideoroncidae, 443, 444 crassopalpus, Acuminochernes, 415, 418, 428, Ideohisiinae, 444 477, 478 Idiochelifer, 486, 487 crassopalpus, Hesperochernes, 476, 477 llliruchernes, 455, 481 crosbyi, A pochthonius, 434, 436 intermedins. Apochthonius, 434 crosbyi, Heterochthonius, 434, 436 ischnocheles. Chelifer, 433 cyrneus, Chernes, 464 ischnocheles, Chthonius, 418, 428, 432, 433 [497] 498 Illinois Natural History Survey Bulletin Vol. 24, Art. 4 Lamprochernes, 450 Lamprochernetinae, 428, 450 Larca, 447 latreillei, Chelljer, 491 latus, Garypus, 447 laurae, Hesperochernes, 476 Inngidactylus, Hysterochelifer. 488 longipalpus, Clithonius, 433 Lustrochernes, 450 lymphatus, Reginachernes, 418, 428, 465, 467, 468 M maculaUis. Clilliomus tetraclielalus var., 433 Menthidae, 447 Menthus, 447 Microbisium, 415, 444 Microcreagris, 444 minor, Lamprochernes, 418, 428, 450, 453 mirabilis, Pseudozaona, 471 Mirochernes, 455, 456, 478 moestus, Apochthonius, 415, 418, 428, 434 moesttis, Clithonius, 434 Monosphyronida, 413, 415, 426, 428, 429, 449 morosus, Chelanops, 466 morosus, Dendrochernes, 464, 466 multispinosns, Heterochthonius, 415, 418, 428, 434, 436 Mundochthonius, 432, 436 muricatus, C/ielifer, 486, 487, 488 muscorum, Obisium, 444 N Neobisiidae, 428, 443, 444 Neobisiidea, 417 Neobisiinae, 428, 444 Neobisium, 444 nigripalpus, Chelifer, 488 nigripalpus, Chelifer caneroides var., 487, 488 nigripalpus, Idiochelifer, 415, 418, 428, 487, 488 nodosus, Chelifer, 450 nodosus, Lamprochernes, 453 o ohlnngus, Chelanops, 450 ohlongus, Chelifer, 450 oblongus, Lamprochernes, 415, 418, 428, 450, 453 occidentalis, Apochthonius, 434 Olpiidae, 447 orlhodactylum, Obisium, 432 ozarkensis, Microcreagris, 444 pallidus, Chelanops, 456, 472 pallidus. Chernes, 456, 472 pallidus, Dinocheirus, 415, 418, 428, 472 pallidus, Hesperochernes, 472 Parachernes, 455, 456 parvulum, Microbisium, 445 parvus, Pselaphochernes, 415, 418, 428, 461 pennsyh'anicus, Clithonius, 433 Pensylt'anicus, Chthonius, 433 Pselaphochernes, 455, 461 Pseudogarypidae, 449 Pseudogarypus, 449 Pseudozaona, 455, 471 pulchellus, Parachernes, 456 R Reginachernes, 456, 465 ronnaii, Parachernes, 456 rossi, Mundochthonius, 416, 418, 428, 436, 437 sanborni, Chelanops, 456, 466 sanborni, Hesperochernes, 466 sandersoni, Mundochthonius, 415, 418, 428 437, 440 scorpioides, Chelifer, 461 scorpioides, Pselaphochernes, 461 solus, Dinocheirus, 418, 428, 474 spinosa, Verrucaditha, 415, 418, 428, 429, 430 spinosus, Clithonius, 429 squarrosus, Parachernes, 415, 418, 428, 456, 472 Sternophoridae, 449 Sternophorus, 449 Syarinidae, 443, 444 Syarinus, 444 tenoch, Dinocheirus, 471 tenuis, Neobisium carolinensis var., 444 tetrachelatus, Chthonius, 415, 416, 418, 428, 433 tetrachelatus, Scorpio, 433 Tridenchthoniidae, 417, 428, 429 Tridenchthoniinae, 428, 429 u I packardi, Blothrus, 443 packardi, Chthonius, 443 packardi. Genus ?, 432, 443 Paisochelifer, 486, 489 unicolor, Hesperochernes, 476 uniformis, Pseudozaona, 471 Verrucaditha, 429 Verrucadithini, 428, 429 virginica, Chelanops, 456 virginicus, Parachernes, 456 w Withiinae, 485 INDEX The following index covers Article 3 of V'oliime 24 of the Illinois Natural History Survey Bulletin. An index of Article 1, T/ie Mosquitoes of Illinois (Diptera, Culicidae) , by Herbert H. Ross, begins on page 95 of this volume. An index of Article 2, The Leafhoppers, or Ciia- dellidae, of Illinois (Eurymelinac—Balcliithinae), by D. M. DeLong, begins on page 367 of this volume. An index of .Article 4, Tlie Pseudoscorpions of Illinois, by C. Clayton Hotf, begins on page 497 of this volume. Algae, 386, 391, 410, 411 Anacharis canadensis, 407 Annuli (annual rings), 388, 390, 393-5, 411 close spacing of, 395, 411 false, 393-5, 411 overlapping, 395 skipped, 395, 411 Anodontia grandis, 384 Aphanizomenon flos-a(/nae, 386, 411 ; see also Algae Aquatic beetle larvae, 399, 407 Dytiscidae, 407 Dytiscus, 407 Haliplidae, 407 Haliplus, 407 Pellodytes, 407 Hydrophilidae, 407 Berosus, 407 Enochrus, 407 Aquatic insects ; see references to aquatic insect groups Aquatic vegetation ; sec references to plant species B Back swimmers, 399 Bass; see Largemouth bass Black bullheads, 377 "Bloom" of algae, 386, 391, 392 Bluegills, 377-412 condition and growth, 391-3, 411, 412 food analysis, 398-407, 411 growth rates, 387-91, 411, 412 histological study, 397, 398, 411 Index of Condition, 391-3 scale analysis, 393-5, 411 sexual cycle, 397, 398, 411 spawning and young fish, 395-7 Buffalo, redmouth, 377 Bullfrogs, 387; see Iso Rana catesbeiana Bullheads, 377 Caddis worms Molannu, 407 Oecetis inconspicua, 407 Ortholrichia, 407 Oxyethira, 407 Camharus propinquus, 387, 407; see also Crayfish virilis, 387, 407; see also Crayfish Carp, 377 Chelydra serpentina, 387; see also Turtles Chrysemys picta marginata, 387; see als Turtles Circuli, 393, 394 Cladocera, 399, 410 Clams, 384 Crappies, 377 Crayfish ; see also Camharus in Fork Lake, 387 in stomachs of bass, 399, 403 D Damselflies, 399, 403, 407 Enallagma, 407 Die-off of plants, 386, 390, 391, 411 Diptera larvae, 399, 403, 411 Ceratopogonidae (biting midges) Bezzia, 403 Palpomyia, 403 Prohezzia, 403 Chaoboridae Chaoborus, 403 Chironomidae (midges) Cliironomos, 403 Tanypus, 403 Culicidae (mosquitoes) Culex, 403 Simuliidae (black flies) Simulium, 403 Stratiomyidae (soldier flies) Odontomyia, 403 Stratiomys, 403 [499] 500 Illinois Natural History Survey Bulletin Volume 24 Dragonflies, 399, 403, 407 Epicordulia, 407 Entomostraca, 386, 399, 403, 407, 410, 411 Cerwdaphnia, 407 Cyclops, 407 Cypris, 407 Daphnia, 399, 403, 407 Diaptomus, 407 Fork Lake, 377-412 condition and growth of fish, 391-3, 411 cropping procedure, 378—81, 411 by use of hook and line, 377, 378, 380, 381, 411 by use of seines, 377, 380, 381 by use of wing nets, 377, 378-81, 387, 407, 411 dam failure, 382-5, 411 fish yield, 381, 382, 411 foods of bass and bluegills, 39C-407, 411, 412 growth rates, 387-91, 411, 412 open water areas, 386, 387 pond habitat, 385-7, 411 scale analysis of fish, 393-5, 411 sexual cycle of fish, 397, 398 spawning and young fish, 395—7, 411 vegetation vs. fish yield, 387, 411 H Hairworms Gordius, 407 Hemiptera Corixa, 407 Notonecta, 407 Homewood Lake, 377, 388 Leopard frogs, 403, 407 Lepomis macrochirus, 377; see also Bluegills M Mayfly nymphs, 403 Micropterus salmoldes, 377; see also Large- mouth bass Midges, 399; see also Diptera larvae MoUusks; see also Snails Musculium, 407 planorbis type snails, 407 Physa, 407 Mount Zion, Illinois, 377, 38 411 N Naiad, 387 Najas guadalupensls, 387 o Oxygen, 410 Pondweed, 386, 411; sec also Potamogeton and Polamogeton Potamogeton, 386, 391, 396, 410, 411; see also Potamogeton, below Potamogeton; see also Potamogeton, above foliosus, 386, 387, 399, 407, 411 nodosus, 386 R Rana catesbelana, 384, 387, 407 pipiens, 407 ; see also Leopard frogs Ridge Lake, 397, 398 Illinois River, 379 Illinois State Department of Conservation, 378, 381 Snails, 399, 403, 407, 411 Spirogyra, 381, 396 Lake Glendale, 397, 398 Largemouth bass, 377-412 condition and growth, 391-3, 411 food analysis, 398-407, 411 growth rates, 387-91, 411 histological study, 397, 398, 411 Index of Condition, 391-3 scale analysis, 393-5, 411 sexual cycle, 397, 398, 411 spawning and young fish, 395-7, 411 Tadpoles, 387, 403, 407 Terrestrial invertebrates, 407 Turtles snapping, 387 painted, 387 w Water boatmen, 399 Water strlders Gerris, 407 Recent Publications A.—ILLINOIS NATURAL HISTORY SURVEY BULLETIN. 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