Bulletin


STA T F O F ILLlN OIS 

DEPARTMEN T Of RFG ISTRATrON N D EDUCATION 


DIVISION OF TI-!1: 


NATURAL I-HSTORY SURVEY 

sn ':i'H EN A FOlt BES, Chicl 

Vol. XUl. BULLETIN A rt. III and IV. 

Art. Ill. A NEW NORTH A MERICAN 
OLIGOCHAETE OF THE GENUS 

H A PLOTAXIS 
BY 

FR ANK SMITH 

Art. IV. A REPRESENTATIVE OF THE 
GENUS TRICHODRILUS FROM ' 

ILLfNOIS 
BY 

JAMES E. KI NDRED 

PRI TTED BY AUTHORITY OF THE STATE OF ILLINOIS 

URBANA. ILLlNOIS 


September, 1918 




ERRATA
Page 97, line 17, for first larval read puital.

Page 112, in legend, for jonessi read jonesii.

Page 114, in legend, for or read of.

Page 125, line 4, for Bonosa read Bonasa.

Page 131, in legend, for Jiirundinaceus read hirudinaceus.

Page 138, last line, for coccoon read cocoon.

Plate XII, explanation page, next to last line, for acrivora read aerivora.

Plate XIII, explanation page, next to last line, for WMte-gruhs read White-gruh.

Page 293, Figure 5a was reversed in printing, and the two items of the legend

should change places.

Page 515, second table, for Pelocoris femorata read Pelocoris femoratus.



Article III.

—

A Nezn' North American Oligochacte of the Genus
Haplotaxis* By Frank Smith.

Introduction

The only papers describing North American Ilaplotaxidae are two
by Forbes ('90 and '90a) in which he describes Haplotaxis cmissarius
from Illinois under the name Phreoryctcs cmissarius. The present paper
extends the original description by giving the positions of the gonads and
spermathecae, hitherto unreported. It also includes the description of a

new species, Haplotaxis forhesi, from the Illinois River.

Forbes found no trace of reproductive organs in his specimens.
The following quotation ('90a : 108) indicates what he regarded as the

important characters in which H. cmissarius dififered from H. mcnkeanus.
the closely allied European congener: "It differs especially l)y the fact

that the dorsal rows of setae are obsolete except on a variable number of

the anterior segments and that the lateral vascular arches extend from
the dorsal to the ventral vessel, instead of connecting only with the lat-

ter." Later, Michaelsen ('99) gave reasons for believing that faulty

observations by earlier European investigators were responsible for these

reported differences, and that the European species actually corresponded-

with the description of Forbes in the absence of dorsal setae from most
of the somites, and in the relation of the commissural blood-vessels. At
this time Michaelsen considered that the various known forms of Haplo-
taxis of the northern hemisphere all belonged to one variable species, H.
gordioides (Hartmann). In a later paper ('05) he described another

species, H. ascaridoides, from Lake Baikal, in Siberia, which differs

chiefly in the number of spermathecae present in sexually mature speci-

mens, there being four pairs in the latter species and but three pairs in

H. gordioides. Since the immature specimens of the two species are

extremely similar, and since only immature specimens of the North
American H. cmissarius were known, Michaelsen concluded ('05 :6T)

that the assumption that the latter species is identical with H. gordioides

is not justifiable without a comparison of the reproductive organs.

Reproductive Organs in Haplotaxis emissarius (Forbes)

Through the kindness of Professor Forbes I have had the privilege

of examining the series of sections on which his description was partly

based. I find vestiges of four pairs of gonads in 10-13. Two speci-

mens in my own collection, from the same region (Champaign, Illinois)

and from the same kinds of situations (tile drains) as were the type

• Contributions from the Zoological Laboratory of the University of Illinois,

No. lis.



44

specimer.j of H. cmissarius. apparently belong to that species. These
specimens have lietter dexelcjiied .gonads, and they arc clearly in l()-i:i'''

(PI. II, Fig. 4). One of the specimens has also three pairs of organs that

are almost certainly degenerating spermathecae. They are in the ante-

rior parts of T-9 (PI. II, Fig. 4), and open in 6/7-8/9 at the level of

the lateral line of either side. Since the number and positions of the

gonads and of the spermathecae in H. cinissariiis are the same as in H.
gordioidcs. the actual status of the former must remain undetermined

until still more can be learned about the reproductive system. We have

no information concerning the sperm ducts, oviducts, sperm sacs, or

ovisacs. These may easily furnish distinctive specific characters.

A New Species from the Illinois River

In 1894 and 1895, while in service for the Illinois State Laboratory

of Natural History at the Biological Station on the Illinois River, the

writer found many specimens of a Haplotaxis species in the wet banks of

the river near Havana, Illinois, and preserved a considerable number,
assuming that they were H. cmissarius and that their reproductive organs

might be sufficiently developed for description. Several series of sec-

tions were made, but a preliminary study showed that the specimens were
not sexually mature, and as an anomalous relation of the gonads was
apparent it seemed advisable to wait for better developed specimens.

During the interval of over twenty years the desired specimens have not

been obtained, and a recent study of the' material at hand has led to the

unexpected discovery that the Illinois River worms belong to a species

distinct from H . cmissarius.

Haplotaxis forbesi, sp. nov.

Length, 100-150 mm. Diameter, 0.6-0.7 mm. Somites, 260-284.

Prostomium approximately twice as long as wide. Setae, two to four

per somite ; dorsal setae much the smaller and limited to a few anterior

somites. Gizzard in part of 4-5. Nephridia large in 12-14 and posterior

to 17. Spermaries : one pair, in 10. Ovaries paired; in 15 and 16.

Cotypes, in the collection of the Illinois State Laboratory of Natural

History (Accessions Cat. Nos. 27136 and 27137), and in the collection of

the writer. Named for Professor S. A. Forbes, who first made known
the presence of Haplotaxidae in North America.

But few of the specimens were preserved entire. Only the anterior

30 or 40 somites were saved in the case of most specimens, since short

pieces were much more easily prepared for sectioning. Transverse,

sagittal, and frontal sections of eight anterior ends, and cleared speci-

mens of nine other anterior ends were used in the study of the more
important characters.

external characters

The measurements given above—length, 100-150 mm., and diameter,

0.6-0.7 mm.—are based on alcoholic material. The number of somites

' Arabic numerals are used to designate the somites.



45

in apparently complete specimens is somewhat less than :300, The pro-

stomium is without terminal pore and in some specimens transverse

grooves are evident. Its length anterior to the mouth is nearly twice its

width and equals the distance from the mouth to the middle or end of

the fourth somite. The first five somites are shorter and broader than

those next following and give the impression of a slight degree of cephal-

ization, which is also manifest in the internal structure (PI. II, Fig. 7).

.\ distinct groove which seems, on the dorsal and lateral walls, to define

clearly the anterior border of the first somite makes that somite appear
slightly longer than the second, and apparently locates the mouth-opening
on the mid-ventral surface of the somite rather than at its anterior

margin. This leaves but a short interval between the mouth and the

intersegmental groove 1/2. If a similar state of things exists in other

species it may account for the apparent extreme shortness of the first

somite which has often been mentioned. I find a similar condition in

H. cniissarins.

The ventral setae (PI. II, Fig. (J) are of the ordinary haplotaxid

type, with nearly straight inner shaft, slightly developed nodule at about

one-third of the length of the seta from the distal end, and distal part

strongly curved. Ordinary measurements are 0.30-0.32 X 0.022 mm.
The dorsal setae are very much smaller (0.125 X 0.007 mm.), begin quite

uniformly on the fifth somite, and are present on only the next following

12-20 somites. This character is presumably not of much systematic

importance but is fairly uniform in a considerable number of specimens.

The setal distances are approximately indicated by the following formula

in which / represents the lateral line : aa : al : Id : dd = 4: : 4 : 3 : 8. No
clitellum nor genital papillae have been found.

li\'TERN.\L CHARACTERS

The buccal region ( Benham, '04 :301) is thin-walled and connected

to the body wall by numerous muscular strands, and extends through the

first three somites. The gizzard has its chief development in the pos-

terior part of the fourth, and the anterior part of the fifth, somite, where
the muscular wall is strongly thickened. The vascular system much
resembles that already described for other species. The dorsal vessel

forks just posterior to the brain. The branches extend anteriorly and
then posteriorly and, after a somewhat tortuous course, unite in the pos-

terior part of the third somite and form the anterior part of the ventral

vessel. One pair of slender commissural vessels in each of the setigerous

somites connects the dorsal and ventral vessels. The connections pos-

terior to somite 4 are in the posterior part of the somites, close to the

septa. The connections of the vessels of each of somites 2-4 are in the

anterior part of the following somite.

The distribution of the nephridia ditTers from that usually found in

the genus, the peculiarities of arrangement being correlated with those

of the reproductive organs, to be described later. Ordinary nephridia

like those described in other species of the genus are found in 12-14 and



4G

in 18 and the following somites (PI. Il, Fig. 3). One specimen has a

large nephridium on one side of 9, and a few have fairly large nephridia

in 15 and 16. They are regularly much smaller pr absent in 10, 11, and
17, and in some specimens in 15 and 16.

The brain differs somewhat in shape from that of H. cinissarins and
certain other species. The length of the median antero-posterior axis is

about equal to the greatest lateral diameter (PI. II, Fig. 1), and the

greatest dorso-ventral axis is about three-fourths as great. The posterior

surface is but slightly concave, and the anterior surface is conical with

the apex somewhat rounded. In median frontal sections of the brain,

the anterior margins include an angle of about 90°. The peculiar

cushions of cells which support the ventral nerve cord are. as far as

observed, found associated with all the ganglia except the first one. Those
related to the second and third ganglia, in somites 3 and 4, are small and
without the lateral wing-like extensions, and the others are larger and
have such extensions more or less developed. No examination has been

made of their distribution in the posterior part of the worms.

The reproductive organs are but incompletely developed in all of

the specimens examined, but the gonads are large and unmistakable.

Eight sectioned specimens and nine specimens cleared in cedar oil are per-

fectly uniform in having one pair of gonads in 10 and one pair in each

of somites 15 and 16 (PI. II, Fig. 3). The anterior pair are doubtless

spermaries and the other two pairs are ovaries. There are vestiges of

spenniducal funnels and of the adjacent parts of the sperm ducts, but no
traces of the location of the spenniducal pores. Two sectioned speci-

mens show sufficient vestiges of the oviducal apparatus to indicate that

the oviducal pores were in the anterior parts of 16 and 17 and dorso-

laterad of the lines connecting the ventral setae of either side of the

worm. One of the two specimens has an additional ovary of small size

on one side of 17 but has no corresponding oviduct. The wide separa-

tion of the ovaries from the spermaries and the extreme posterior posi-

tion of the former are characters that are very aberrant, not only for the

genus, but for the Oligochaeta as a whole. No traces of sperm sacs,

ovisacs, or spermathecae have been detected.

General Discussion

The marked differences in the relations of the gonads are sufficient

to distinguish H. forhesi from H. cmissarius, but it differs also in its

smaller size ; in the small number of somites in apparently complete

worms ; and in having fewer somites with dorsal setae. The shape of the

brain also is quite different in the two species (PI. II, Fig. 1 and 2), as

shown by a comparison of the following three measurements : median
antero-posterior axis, greatest lateral diameter, and greatest dorso-ventral

axis. These ratios for H. forbesi. in the order mentioned, are 4:4:3;
and those for H. emissarius, 5:8: 4.

The scanty records of the occurrence of H. forbesi give almost no
information concerning its distribution or the precise kinds of situations



4r

in which it is to be found at different times of the year. The records

are confined to ]894 and 1895. when careful periodical surveys were
made of the plant and animal life of the Illinois River and its connected

lakes at the Biological Station. Although there were numerous dredging

operations at different places in the river channel, the only specimen
taken in this way was obtained December IS. 1894. at Station E. directly

opposite a place on the shore where all our other specimens of H. forhcsi

were taken. In May. 1894. numerous specimens were found on both

sides of the river at Station E. in the water-soaked banks, just above the

water level. In the interval between April 13 and 'I'i. 1895. numerous
specimens were found at the same station, but in the west bank of the

river only. Their abundance is indicated by a memorandum stating that

^9 specimens were taken from the mud obtained by an assistant by three

successive scoops with the hands. At this time a careful search was
made for specimens in other locations at various places down the river

for nearly six miles, but none were found.

Apparently they are nearer to the surface in .\pril or May than at

other times of the year. Just where they are during the remainder of

the year is entirely unknown. Since H. onissariiis is subterranean in

habit, being collected chiefly from wells and tile drains, it seems reason-

able to suppose that the new form also may have a subterranean habitat

during most of the year.

The time of sexual activity of H.forbcsi is unknown. The speci-

mens collected are all of about the same stage of development, with

gonads quite large and often extending nearly to the posterior septum,

but without any signs of cell-division activity. We have no records of

partially grown, juvenile specimens.

It seems probable that both H. cniissariits and H. forbesi, and per-

haps other species of the genus, actually occur in many parts of North
America, but have thus far escaped notice except in Illinois.

LiTER.\TURE Cited

Benham, W. B.

'04. On a new species of the genus Haplotaxis ; with some remarks

on the genital ducts in the Oligochaeta. Quart. Jour. Micr. Sci.,

48 : 299-3-22.

Forbes, S. A.

'90. Note on an American species of Phreorvctes. Am. Nat., 24 :

47'?-478.

'90a. On an American earthworm of the familv Phreoryctidae. Bull.

111. State Lab. Nat. Hist., 3 : ]0:-U(i.

Michaelsen, W.
'99. Beitrage zur Kenntniss der Oligochaten. Zool. lahrb., Abth. f.

Syst., Geogr., u. Biol. d. Thiere, 12 : 105-144.

'05. Die Oligochaeten des Baikal-Sees. Wiss. Ergebn. Zool. Exped.

Baikal-See unter Leit. v. A. Korotneff, 1 Lief., pp. 1-68.



48

Plate II

Fig. 1. Haplotaxis forbesi. frontal section tlirough prostomium and brain in plane
of longest antero-posterior axis of latter. X 105.

Fig. 2. Haplotaxis emissarius, same as above.

Fig. 3. Haplotaxis forbesi. diagram showing location of gonads, ducts, and
nephridia (of left side). (Double lines indicate large normally devel-
oped nephridia, and single lines are in somites in which nephridia are
imperfectly developed, or sometimes absent.

)

Fig. 4. Haplotaxis emissa?-ius, diagram showing location of gonads, spermathecae,
and nephridia (of left side). (Double and single lines for nephridia
are used, as in Fig. 3.)

Fig. 5. Haplotaxis forbesi. dorsal seta. X 175.

Fig. 6. The same, ventral seta. X 175.

Fig. 7. The same, longitudinal section through five anterior somites in a plane
slightly oblique to the median sagittal plane and laterad of the same.
The distal ends of ventral setae, the relation of the mouth to the first

somite, and part of the musculature of the alimentary tract are shown.
X 70.

1

October 1. IHIS.



Plate IT