Durden_59-66.qxd INTRODUCTION A large number of surveys on the arthropod para- sites, particularly ticks, of impalas, Aepyceros melampus, have been conducted in southern Africa (for review see Horak, Gallivan, Braack, Boomker & De Vos 2003). The collection techniques employed in a number of these surveys were sufficiently sen- sitive to collect lice and the louse burdens of im- palas have been recorded by Horak (1982), Horak, Boomker, Kingsley & De Vos (1983), Van Dyk & McKenzie (1992), Matthee, Horak & Meltzer (1998) and Horak et al. (2003). In other surveys the pres- ence of lice has been recorded incidentally. The four louse species (two chewing lice in the genus Damalinia and two sucking lice in the genus Lino- gnathus) known to infest impalas have been listed by Ledger (1980), and were recovered in most of the surveys, but in some of them an unknown Linognathus sp. was encountered. On examination these lice appeared to be the same as those collected during October 1965 from an impala at Kamazeu, Zimbabwe (then Rhodesia), and those collected by J.A. Ledger during August 1968 from an impala at Skukuza in the Kruger National Park (KNP), South Africa. Weisser (1975) described these lice from an entire female and the terminalia of the male in an unpublished monograph on the Linognathidae. Several thousand specimens of this louse, designated only as Linognathus sp., have been collected from impalas in the KNP by Horak et al. (2003). The same louse has been col- lected from impalas examined on a privately owned 59 Onderstepoort Journal of Veterinary Research, 71:59–66 (2004) Linognathus wweisseri n. sp. (Phthiraptera: Linognathidae) of impalas, Aepyceros mmelampus: description and biology L.A. DURDEN1 and I.G. HORAK2 ABSTRACT DURDEN, L.A. & HORAK, I.G. 2004. Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas, Aepyceros melampus: description and biology. Onderstepoort Journal of Veterinary Re- search, 71:59–66 The adult male and female and first instar nymph of the sucking louse Linognathus weisseri n. sp. are described. This louse was collected from impalas, Aepyceros melampus, at three localities in Limpopo Province, and at three in Mpumalanga Province, South Africa. Although it usually account- ed for only a small proportion of the total louse burden, its overall prevalence exceeded 27 %. Its prevalence on adult male impalas (9 %) was significantly lower (P = 0.004) than that on adult females (39 %), but did not differ among age classes. However, the intensity of L. weisseri infestation was higher on lambs than on yearlings and adults, and peaked on impalas in late winter to early sum- mer. Five species of lice are now known to parasitize impalas and a key for distinguishing adults of these species is included. Keywords: Aepyceros melampus, impalas, lice, Linognathus weisseri, Phthiraptera 1 Department of Biology and Institute of Arthropodology and Parasitology, Box 8042, Georgia Southern University, States- boro, GA 30460, United States of America 2 Department of Veterinary Tropical Diseases, Faculty of Vet- erinary Science, University of Pretoria, Onderstepoort, 0110 South Africa Accepted for publication 17 October 2003—Editor game ranch by Matthee et al. (1998). In this paper the adults and first instar nymph of this louse are described and illustrated, and its biology, garnered from Matthee et al. (1998) and Horak et al. (2003) as well as other sources, outlined. MATERIALS AND METHODS The impalas from which the louse was collected had been processed for ectoparasite recovery as described for greater kudus, Tragelaphus strep- siceros, by Horak, Boomker, Spickett & De Vos (1992), and the lice were recovered from the pro- cessed material as described by Horak et al. (2003). The localities at which Linognathus weisseri was collected and its prevalence on impalas at these localities are summarized in tabular format and its seasonal occurrence is graphically illustrated. Descriptive format Taxonomic descriptions follow the format of Musser & Durden (2002) with modifications specific to Lino- gnathus used by Weisser (1975) and Weisser & Ledger (1977). Names of setae are from Kim & Lud- wig (1978); these names are spelt out when first used (with abbreviations provided in parentheses), and subsequently abbreviated. DESCRIPTION Male (Fig. 1): length of holotype, 1.32 mm; mean, 1.32 mm; range, 1.26–1.36 mm (n = 6). Head, thorax and abdomen moderately sclerotized. Head longer than wide, rounded, with blunt anteri- or apex. Three Apical Head Setae (ApHS), two Dorsal Pre-antennal Head Setae (DPaHS), two Supra-antennal Head Setae (SpAtHS), two Sutural Head Setae (SHS), two Dorsal Posterior Central Head Setae (DPoCHS), one Dorsal Marginal Head Seta (DMHS), two to three Ventral Pre-antennal Head Setae (VPaHS), and one Ventral Principal Head Seta (VPHS) on each side; VPHS moderate in length. Antennae 5-segmented, relatively long and slender, with basal segment wider than long and wider than second segment. Thorax broader than head with curved margins widening posteriorly; thoracic sternal plate absent; mesothoracic spiracle sub-circular, 0.04 mm in diameter; Dorsal Principal Thoracic Seta (DPTS) fairly short (0.085 mm) with one (rarely two) small Dorsal Mesothoracic Seta (DMsS) between spira- cle and DPTS on each side; one short Dorsal Pro- thoracic Seta (DPtS) on each side. Legs long and relatively narrow; mid-legs and associated claws larger and more robust than fore-legs; hind-legs slightly larger than mid-legs; hind coxae sub-trian- gular; fore and mid coxae as depicted in Fig. 1A. Abdomen wider than thorax with curved margins and fine crenulations on dorsal and ventral surfaces as shown in Fig. 1A. Paratergal plates, tergites and sternites (except sub-genital plate) absent as is typ- ical for Linognathus; six moderately-sized spiracles 60 Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas FIG. 1 Linognathus weisseri, n. sp., male. A. Dorso-ventral view. B. Genitalia. Both scale bars = 0.1 mm on each side; Dorsal Marginal Abdominal Setae (DMAS) associated with third spiracle consisting of one long and one moderately long (but clearly shorter) seta; DMAS associated with fourth to sixth spiracles each consisting of two long setae; other abdominal setae short to moderate in length (except for four long posterior setae ventrally) and more or less arranged in 12 ventral rows (anterior to sub- genital plate) and 14 dorsal rows. Dorsal setal rows consisting of the following approximate numbers of setae from anterior to posterior: 4, 6, 6, 12, 10, 5, 10, 6, 12–14, 6, 12–14, 16–18, 2, and 14–18. Most dorsal setae are Dorsal Central Abdominal Setae (DCAS), but rows 3–5 also have Dorsal Lateral Abdominal Setae (DLAS) as shown in Fig. 1A. Ventral setal rows anterior to sub-genital plate con- sisting of the following approximate numbers of setae from anterior to posterior: 2, 2, 4, 4, 4, 6, 4, 6–7, 6, 10–11, 4, and 2. Most ventral abdominal setae are Ventral Central Abdominal Setae (VCAS) but some in rows 6, 8 and 10, are Ventral Lateral Abdominal Setae (VLAS) as shown in Fig. 1A. Two groups of two to three short DLAS lateral to sub- genital plate on each side. Genitalia: V-shaped sub-genital plate with irregular anterior and lateral margins, and central elliptical lacuna enclosing two elongate setae (Fig. 1A). Basal apodeme about twice as long as parameres, well sclerotized, constricted medio-laterally, and with posterior fork (Fig. 1B); parameres curved, broad anteriorly and tapering posteriorly, with dis- tinct surface patterning (Fig. 1B); endomere large and elliptical; pseudopenis relatively long, distinctly extending beyond apices of parameres. A pair of lateral sclerites bearing numerous setae is present near the apex on segment IX. Female (Fig. 2): length of allotype, 1.68 mm; mean, 1.75 mm; range, 1.60–1.88 mm (n = 10). Head, thorax and abdomen as in male with the fol- lowing exceptions: Head with lateral margins relatively straight and parallel; two Dorsal Anterior Head Setae (DAnHS) on each side. Thorax less constricted than in male at junction with abdomen giving the overall body an elliptical shape (Fig. 2A). DPTS length, 0.128 mm. Abdomen: DMAS associated with third spiracle consisting of one short seta and one of moderate length; abdominal setae more or less arranged in 12 rows ventrally (anterior to gonopods) and 17 rows dorsally although anterior dorsal rows are dif- ficult to distinguish (Fig. 2A). Dorsal setal rows con- sisting of the following approximate numbers of setae from anterior to posterior: 2, 6, 12, 10, 6, 12, 6, 12, 10, 6, 10, 6, 10, 6, 10, 12–14; most dorsal setae are DCAS but rows 4, 6, 8, 11, 13, and 15 also have DLAS as shown in Fig. 2A. A few DCAS and DLAS are elongate (Fig. 2A). Ventral setal rows anterior to gonopods consisting of the follow- ing approximate numbers of setae from anterior to posterior: 4, 4, 4, 6, 4, 12, 4, 12, 4, 12, 6, 8, 6. Most ventral setae are VCAS but rows 4, 6, 8, and 10 61 L.A. DURDEN & I.G. HORAK FIG. 2 Linognathus weisseri, n. sp., female. A. Dorso-ventral view. B. Genitalia. Both scale bars = 0.1 mm also have VLAS as shown in Fig. 2A. Two to four short VLAS on each side at base of gonopods on segment VIII. Genitalia (Fig. 2B): sub-genital plate sub-rectangu- lar and bearing 10–16 small setae; gonopods on abdominal segment VIII finger-like with sclerotized lateral margins and rounded apices, each bearing seven to nine setae that are short medially and increase to moderate length postero- laterally; row of tiny setae situated medially between bases of these gonopods; gonopods on abdominal segment IX situated terminally and tapering to form forficu- late apical lobes each bearing a row (possibly two separate rows) of hair-like setae. First instar nymph (Fig. 3): mean length, 1.09 mm; range, 1.02–1.20 mm (n = 3). Head moderately sclerotized; thorax and abdomen lightly sclerotized and with surface sculpting as shown for abdomen of male (Fig. 1A). Head shaped as in male but with small, pointed, antero-lateral projection immediately posterior to antennal insertion on each side. Dorsal head setae as in male. Ventral head with three ApHS and one VPHS on each side. Thorax distinctly wider than head, with mesotho- racic spiracle (0.03 mm in diameter) and one VPTS (0.084 mm in length) on each side. Abdomen at widest point slightly wider than thorax; six moderately-sized spiracles, three pairs of long DMAS posteriorly (each pair borne on a protruding area of integument), and one pair of moderately long DMAS anterior to these on each side. Dor- sally, with nine pairs of DCAS of moderate length; ventrally, with one pair of short anterior VCAS and three pairs of posterior VCAS of moderate length. Specimens examined Holotype male, allotype female and 17 paratypes (five males, nine females, three first instar nymphs) ex adult female Aepyceros melampus (Lichtenstein), Nwaswitshaka River Bridge, Skukuza (24°58’S, 31°36’E), Kruger National Park, Mpumalanga Prov- ince, South Africa; 24 November 1982; Coll.: I. G. Horak. Deposition of types Holotype male, allotype female and one paratype nymph (Accession number TM 2031126) deposited in the U.S. National Museum of Natural History, Washington DC. Paratypes will also be deposited in the Natural History Museum, London. Etymology We have pleasure in naming this species after Dr Christian F. Weisser who first described the entire female and the male genitalia of this species in his dissertation but did not publish the description. We greatly appreciate Dr Weisser’s encouragement to proceed with this description. Synonymy Linognathus melampi Weisser, 1975; this is an un- published manuscript name. Weisser (1975) stated that a female holotype, a male allotype (two slides) and another four females and two males (four slides) of L. melampi had been deposited in the South African Institute of Medical Research (SAIMR) Collection under “Rev. (sic) No. L 232” and “L 231” respectively, but we have been unable to locate these specimens. Diagnosis Linognathus weisseri is a fairly small and distinct member of its genus. It can be easily distinguished 62 Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas FIG. 3 Linognathus weisseri, n. sp., first instar nymph. Dorso- ventral view. Scale bar = 0.1 mm from Linognathus elblae, Linognathus breviceps and Linognathus nesotragi by the absence of hook- shaped sclerotized margins on the forehead. It can be distinguished from other sucking lice on impalas by the absence of a thoracic sternal plate (which is present in Linognathus aepycerus), the almost par- allel post-antennal margins of the head (which are distinctly bulging in L. aepycerus), the slender body shape (which is globular in Linognathus nevilli) and the relatively small spiracles (which are large in L. nevilli). The shape of the subgenital plates and gen- italia in both sexes further distinguish L. weisseri from other described species of Linognathus includ- ing those found on impalas. KEY TO ADULT LICE PARASITIZING IMPALAS 1A. Head wider than thorax (chewing lice, Damalinia spp.) . .2 1B. Head narrower than thorax (sucking lice, Linognathus spp.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2A. Head sub-triangular and elongate (about twice as long as wide) with small apical notch . . . . . . .Damalinia elongata 2B. Head squarish and short (about 1.2 times long as wide) with tapering anterior and posterior lateral margins and large apical notch . . . . . . . . . . . . . . .Damalinia aepyceros 3A. Body slender (abdomen not more than twice as wide as thorax at widest point), abdominal spiracles small . . . . .4 3B. Body globular (abdomen 2.5–3 times as wide as thorax at widest point), abdominal spiracles large . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Linognathus nevilli 4A. Thoracic sternal plate present, post-antennal head margin distinctly convex . . . . . . . . . . . . . .Linognathus aepycerus 4B. Thoracic sternal plate absent, post-antennal head margin nearly straight or mildly convex . . . .Linognathus weisseri RESULTS AND DISCUSSION Linognathus weisseri was collected from impalas at five of the six localities at which impalas were exam- ined within the Kruger National Park (KNP), and was also present on impalas on Letaba Ranch, a private game farm in north-eastern Limpopo Province, South Africa (Table 1). Although L. weisseri usually accounted for only a small percentage of the total number of lice collect- ed, it was common on impalas, with an overall prevalence of 28.8 % on animals examined in the KNP and 17.8 % on animals on Letaba Ranch. In contrast L. aepycerus and L. nevilli were present in all localities in the Limpopo and Mpumalanga Prov- inces at which impalas were examined, with the for- mer having an overall prevalence rate of 79.4 % and the latter 55.9 %. The prevalence and intensity of infestation of L. weisseri on impalas in the KNP did not differ between the Skukuza and Mbiyamiti regions in 1980/ 81, or between Skukuza and Pafuri in 1992/93 (P = 0.35). At Skukuza the prevalence did not differ between 1980/81 and 1992/93 (P = 0.74) but the intensity of infestation was higher in 1980/81 than in 1992/93 (P = 0.01). The prevalence was consid- erably lower (P = 0.004) on adult male impalas (9 %) than on adult females (39 %), and none were collected from the adult males at Crocodile Bridge. The prevalence and intensity of infestation of L. aepycerus on the same animals did not differ sig- nificantly between the sexes (P > 0.16), whereas those of L. nevilli did (P < 0.006) (Horak et al. 2003). 63 L.A. DURDEN & I.G. HORAK ����� � � � � �� � � �� � � �� � � ���� � � � � ���� � � � ���� � � � ����� � �� � �� �� �� �� ��������� �� � �� FIG. 4 Seasonal pattern of intensity of infestation of Linognathus weisseri on impalas at Sku- kuza and in the Mbiyamiti regions, Kruger National Park, South Africa during 1980/81. The monthly sample ranged from 4–13 impalas 64 Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas T A B L E 1 Li no gn at hu s w ei ss er ic o lle ct e d f ro m im p a la s a t va ri o u s lo ca lit ie s in S o u th A fr ic a N o . e xa m in e d N o . o f L. w ei ss er ic o lle ct e d P ro p o rt io n L o ca lit y C o o rd in a te s P ro vi n ce P e ri o d o f to ta l l o u se (N o . in fe st e d ) N ym p h s A d u lts T o ta l b u rd e n ( % ) N yl sv le y 2 4 °2 9 ’S , 2 8 °4 2 ’E L im p o p o 1 9 7 5 /7 6 3 6 (0 ) 0 0 0 0 L e ta b a R a n ch 2 3 °4 0 ’S , 3 1 °0 4 ’E L im p o p o 1 9 9 4 /9 5 4 5 (8 ) 2 5 4 2 9 0 .5 8 P a fu ri 2 2 °2 7 ’S , 3 1 °1 9 ’E L im p o p o ( K N P ) 1 9 8 0 – 1 9 9 3 2 5 (5 ) 4 0 3 0 7 0 1 .3 N to m e n i P a n s 2 3 °2 6 ’S , 3 1 °1 4 ’E L im p o p o ( K N P ) Ju ly 1 9 8 2 2 (2 ) 1 0 4 1 4 1 6 .2 8 S ku ku za 2 4 °5 8 ’S , 3 1 °3 6 ’E M p u m a la n g a ( K N P ) 1 9 8 0 – 1 9 9 3 1 3 9 (5 0 ) 1 9 6 4 1 5 6 9 3 5 3 3 3 .4 6 M b iy a m iti 2 5 °1 7 ’S , 3 1 °3 2 ’E M p u m a la n g a ( K N P ) 1 9 8 0 /8 1 6 0 (1 1 ) 2 4 0 1 7 2 4 1 2 3 .8 1 C ro co d ile B ri d g e 2 5 °2 2 ’S , 3 1 °5 4 ’E M p u m a la n g a ( K N P ) 1 9 8 0 /8 1 1 2 (0 ) 0 0 0 0 L o w e r S a b ie 2 5 °0 6 ’S , 3 1 °5 5 ’E M p u m a la n g a ( K N P ) O ct o b e r 1 9 8 2 1 (1 ) 8 0 0 8 0 5 .4 3 S t L u ci a G a m e P a rk 2 8 °2 3 ’S , 3 2 °3 0 ’E K w a Z u lu -N a ta l M a y 1 9 8 4 2 (0 ) 0 0 0 0 The prevalence of L. weisseri did not differ among age classes (P = 0.44), but the intensity of infesta- tion was higher on lambs than on yearlings and adults (P = 0.01). Two impala lambs, less than 2 weeks of age were examined, and one was already infested with L. weisseri. Both month-old lambs examined were infested. The distribution of L. weisseri on the bodies of 40 impalas, on which it could be determined, is sum- marized in Table 2. Most lice were present on the necks, trunks, upper legs and tails of the impalas. Unfortunately the collecting procedure followed by Horak et al. (2003) did not allow for the determina- tion of a more accurately defined distribution pat- tern. Although the collection procedure of Matthee et al. (1998) does permit for such a determination, they collected too few L. weisseri to ascertain its preferred body surface locality. In contrast L. aepy- cerus is present on the head, neck, body, legs and tail of impalas, with no specific preferred locality, whereas L. nevilli has a pronounced preference for the hind legs (Matthee et al. 1998). The intensity of infestation of L. weisseri, deter- mined from the burdens of the 123 impalas exam- ined in sets of 4–13 animals at monthly intervals at Skukuza and in the Mbiyamiti region, peaked from August to November (Fig. 4). That of L. aepycerus on the same animals peaked from July to October, and although there was no clear pattern of season- ality for L. nevilli, most were collected during March, April, August, October and November (Horak et al. 2003). Although no L. weisseri were collected from January to June 1980, it was present on impalas examined during some of these months in 1981 and in 1992/93. Not only does the morphology of L. weisseri differ from that of L. aepycerus and L. nevilli, the two other anopluran lice that infest impalas, but its biology also differs, thus confirming its identity as a valid separate species. ACKNOWLEDGEMENTS We thank Dr Christian Weisser, University of Hei- delberg, Germany, for encouraging us to formally describe this new species, and the South African National Parks for placing the impalas and the facil- ities in the KNP at our disposal. Our thanks also go to Dr Jim Gallivan of Ottowa, Canada for statistical processing of the data. REFERENCES HORAK, I.G. 1982. Parasites of domestic and wild animals in South Africa. XV. The seasonal prevalence of ectoparasites on impala and cattle in the northern Transvaal. Onderste- poort Journal of Veterinary Research, 49:85–93. HORAK, I.G., BOOMKER, J., KINGSLEY, SHIRLEY A. & DE VOS, V. 1983. The efficacy of ivermectin against helminth and arthropod parasites of impala. Journal of the South Afri- can Veterinary Association, 54:251–253. HORAK, I.G., BOOMKER, J., SPICKETT, A.M. & DE VOS, V. 1992. Parasites of domestic and wild animals in South Africa. XXX. 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HORAK TABLE 2 Distribution of Linognathus spp. on the bodies of impalas Total number (proportion %) of lice recovered Louse species No. of impalas examined Head and ears Neck, trunk, upper Lower legs and feet legs and tail Linognathus weisseri 40 104 (3.2 %) 3 147 (96.6 %) 8 (0.2 %) Linognathus aepycerus* 45 349 (18.5 %) 1 041 (55.1 %) ** 498 (26.4 %) *** Linognathus nevilli* 45 15 (0.6 %) 224 (9.5 %) ** 2 130 (89.9 %) *** * Adapted from Matthee et al. (1998) ** Neck, trunk and tail *** Legs and feet MUSSER, G.G. & DURDEN, L.A. 2002. Sulawesi rodents: de- scription of a new genus and species of Murinae (Muridae, Rodentia) and its parasitic new species of sucking louse (Insecta, Anoplura). American Museum Novitates, 3368:1– 50. VAN DYK, P.J. & MCKENZIE, A.A. 1992. An evaluation of the effectivity of the scrub technique in quantitative ectoparasite ecology. Experimental and Applied Acarology, 15:271–283. WEISSER, C.F. 1975. A monograph of the Linognathidae, Ano- plura, Insecta. (excluding the genus Prolinognathus). Un- published Ph.D. dissertation, University of Heidelberg. WEISSER, C.F. & LEDGER, J.A. 1977. Two new Linognathus (Phthiraptera: Linognathidae) from roan and nyala (Bovidae) in southern Africa. Journal of the Entomological Society of South Africa, 40:283–289. 66 Linognathus weisseri n. sp. (Phthiraptera: Linognathidae) of impalas