Pygolabis eberhardi, Keable, Stephen J. & Wilson, George D. F., 2006

Keable, Stephen J. & Wilson, George D. F., 2006, New species of Pygolabis Wilson, 2003 (Isopoda, Tainisopidae, Crustacea) from Western Australia, Zootaxa 1116, pp. 1-27 : 7-15

Pygolabis eberhardi sp. nov. ( Figs 4 C–F, 5–7)

Etymology. This species is named in honour of Dr Stefan Eberhard (Department of Conservation and Land Management), who has actively explored subterranean aquatic habitats in many places around Australia. The last syllable of the species name is similar to the name of the type locality, Hardey River.

Type material. Western Australia: Pilbara Region: Holotype male "specimen 7", body length 13.3 mm, Hardey River Borefield: 22°55.59'S 117°23.06'E, fld. no. PSS 173 26 vii 2003 (M.D. Scanlon, J.S. Cocking) ( WAM C34942). Paratypes: 31 specimens, same data as holotype (AM P70404); 6 males (2 WAM C34943, 4 AM P70405), 3 females (2 WAM C34944, 1 AM P70406), same data as holotype; 118 specimens, same data as holotype except 21 xi 2003 (M.D. Scanlon, J.S. Cocking, H.J. Barron) (AM P70407); male "specimen 1", manca "specimen 3", 22°43'S 117°31'E, fld. no. BES 4850, 1993 (W.F. Humphreys, S.M. Eberhard) ( WAM C34945); male "specimen 2", body length 11.4 mm, mouthparts, pereopods and pleopods dissected for examination and illustration or SEM, same data as WAM C34945 (AM P70408); male, body length 11.1 mm, 22°43'S 117°31'E, fld no. BES 4858 1993 (W.F. Humphreys, S.M. Eberhard) ( WAM C34946); male, body length 12.4 mm, 22°55.59'S 117°23.01'E, depth to water 3 m, depth to bottom 17 m, fld. no. PSS 174 26 vii 2003 (M.D. Scanlon, J.S. Cocking) (AM P70409, slide STY001); 1 male, 1 female ( WAM C34947), 2 males (AM P70410), bore NWSLK 220B Ashburton River catchment, 22°55.59'S 117°23.06'E, fld. no. PSS 174, 21 xi 2003.

Other material. 4 males, 5 females, bore NWSLK 58 House Creek, Ashburton River catchment, 22°27.88'S 116°02.18'E, fld. no. PSS 172, 21 v 2004 (M.D. Scanlon, J.S. Cocking) (AM P70411); male, female, bore RED002 Red Hill Well Ashburton River catchment, 22°07.19'S 116°03.89'E, fld. no. PSS 358, 11 viii 2004 (M.D. Scanlon, H.J. Barron) (AM P70412).

Diagnosis. Pleotelson. Distance between uropod insertions and apex more than half length of pleotelson; lateral inflection points of posterior margin closer to uropod insertions than to apex; distance from lateral inflection points of posterior margin to apex greater than from uropod insertions to inflection points; apex rounded, posterior margin indentation absent. Pleopod 2 male endopod appendix masculina. Teeth on lateral margin separated by less than tooth width for more than half of lateral margin length, proximal teeth distinctly longer than lateral teeth in middle of ridge; lateral margin distinctly and broadly projecting — somewhat quadrate with conspicuous rounded proximal angle; distal tip with broad cup; medial distal margin rounded. Uropods. Protopod extending subequal to pleotelson apex.

Description. Body. Medial length 6.08–7.45 width at pereonite 3 (holotype).

Head. Length 0.6–0.78 width (holotype 0.60), 1.03–1.3 pereonite 1 medial length (holotype 1.03); dorsal surface covered with scattered fine setae; antennal notch present; clypeus rounded, proximal width 0.59 head width, extending between antennal insertions, mandibular articular fossa narrower than clypeal height; labrum distally rounded, without setae, symmetrical.

Pereonites. Total medial length 0.5–0.58 body length (holotype 0.50); medially 2–6 subequal and longest, 7 slightly shorter; dorsal surfaces with scattered fine setae, with 1–2 thin transverse cuticular ridges.

Pleonites. Articulation flexible (able to move in vertical and transverse axis); with scattered sparse fine setae; total medial length 0.25–0.28 body length (holotype); 1–4 lengths subequal and shorter than pereonite 7, pleonite 5 length subequal to pereonite 7; respective medial lengths: body length — 0.05, 0.05, 0.05, 0.05, 0.06–0.07 (holotype).

Pleotelson. Medial length 1.36–1.37 width (holotype), 0.45–0.58 pleon length (holotype); distance between uropod insertions and apex 0.56 total medial length of pleotelson; lateral inflection points of posterior margin occurring at 0.44 of distance between the uropod insertions and apex; distance from lateral inflection points of posterior margin to apex 1.3 distance from uropod insertions to lateral inflection points of posterior margin; dorsal surface with scattered simple setae; robust sensillate setae absent, posterolateral margins with 14–20 small non­sensillate simple setae.

Penes. Cross section oval, with elongate thin­walled and tapering extension.

Antennula . Length 0.18–0.22 body length (holotype 0.18); with 17–20 articles (holotype 17); article 1 with few simple setae; articles 1–3 subequal; article 3 without penicillate setae; secondary flagellum rudimentary (minute setose article on article 3 anteromedial distal margin), with several simple setae, penicillate setae absent.

Antenna. 0.48–0.54 body length (holotype 0.48); with 40–42 articles (holotype). Protopod articles 1–3 increasing in length distally, with few simple setae; proximal article 4 subequal to protopod article 3, proximal articles 5–6 longer, increasing in length distally. Flagellum length 0.68 antenna total length.

Mandible. Articular axis approximately at right angles to gnathal edge; left lacinia mobilis large, flattened and toothed, distinctly separated from spine row; right lacinia mobilis indistinctly separated from remainder of spine row; right lacinia mobilis bifurcate with two dentate plates (smaller plate on anterior surface of larger plate); spine row on ridge between incisor and molar, with remaining spines other than lacinia mobilis not bifurcate. Palp length 0.96 mandible length; article 1 with 1 distal simple setae; article 2 with 2 longitudinal rows of setae (1 row setulate and 1 row simple); article 3 weakly curved, with 8–12 setae, setae finely setulate, coarsely spinulate setae absent.

Maxillula. Medial lobe with 4 pappose setae. Lateral lobe with 11 distal robust setae, including 6 denticulate; ventral face setae absent.

Maxilla. Outer lateral lobe with 6 comb setae. Medial lobe medial margin slightly concave distally; extent of setae confined to distal half of medial margin past insertion of lateral lobes.

Maxilliped. Epipod length 1.07 width; distal margin narrowly rounded. Palp basal width 0.21 length. Endite with 5 coupling hooks on right side (3 large, 2 small).

Pereopods. Coxae 2–3 lateral sutures well indented; coxae 4–7 medial shape triangular, with broad medial extension toward midline. Pereopods 1–7 respective lengths: body length — 0.19, 0.27, 0.25, 0.22, 0.23, 0.23, 0.24. Pereopod 1 with robust toothed sensillate setae on ventral margins of propodus and carpus, robust smooth sensillate setae on ventral margins of carpus (P2–3) and merus (P1–3), 4–7 with few sensillate setae. Pereopod 1 propodus and carpus with robust bidenticulate sensillate setae, respectively 6, 4. Pereopods 2–3 carpus with 18–23 (male 18, female 23), 13 robust sensillate setae respectively, robust sensillate setae smooth, lateral row with 7–15 robust setae (7 in male, 15 in female).

Pleopods. When lying flat on ventral surface of pleon, weakly enclosed laterally by respective pleonite pleurae; 2–4 overlapped by preceding pleopod by about half length. Protopods lateral margin bearing elongate sensillate setae; medial margin curved serrate robust setae present. Exopods with fewer than 26 marginal plumose setae. Pleopod 1 endopod sexually dimorphic (twisted and with several long denticulate apical setae in males, thin and flattened with several short plumose apical setae in females); length in female 0.53 exopod length; with only 2–3 small distal plumose setae (female), or with several long minutely denticulate setae (male). Pleopod 2 male endopod appendix masculina length 0.82 distance from base of appendix masculina to distal margin of exopod, lateral margin with 22–25 teeth (paratype with 22 in light microscope picture and 24 in SEM, 25 in line drawing of holotype), including 6–8 distal elongate spine­like teeth (most distal spines smaller than others, holotype 8); distal segment length 1.12–1.53 width (1.12 line drawing holotype, 1.27 light microscope, 1.53 SEM); distal tip cup without teeth on distal lateral margin. Pleopod 2 female endopod setae absent. Pleopods 3–5 endopod setae absent.

Uropods. Length 0.12–0.18 body length (holotype 0.12), 0.46–0.7 pleon length (holotype 0.46). Protopod length between insertion and distal margin 1–1.04 length between insertion and pleotelson apex (holotype); with 18 small tooth­like setae along medial margin; ventrolateral margin long thin laterally projecting setae present (abundant). Endopod length 0.65–0.72 protopod length (holotype 0.65), 1.53–1.67 exopod length (holotype); medial margin without penicillate setae, with 7 small tooth­like setae (mostly placed proximally). Exopod length 0.39–0.47 protopod length (holotype 0.39).

Remarks. The elongate pleotelson (extending subequal to the distal margin of the uropod protopod) with rounded apex that lacks an indentation, combined with the appendix masculina (which has a broadly projecting quadrate lateral margin, with closely spaced teeth that are longer in the proximal portion of the margin relative to those in the middle of the margin) are characters that diagnose this species. Two samples, (AM P70411 and AM P70412), were collected at a relatively large distance from the type locality (150– 163 km). Despite matching the description of this species closely, particularly in the diagnostic features of the distinctive appendix masculina, they are excluded from the type series to allow a precise designation of the type locality.

Distribution. Hardey Borefield 22°43.00–55.59'S 117°23.06–31.00'E and two localities to the north west, 22°07.19–27.88'S 116°02.18–03.89'E, Pilbara Region, Western Australia.

Figures

FIGURE 4. Comparison of the appendix masculina (male pleopod 2 endopod, right side) of three species of Pygolabis: P. humphreysi (AM P 64993) A – B; P. eberhardi sp. nov. (AM P 70408) C – F; P. weeliwolli sp. nov. (AM P 70413) G – I. Light micrographs of parts (A, C, G) prior to SEM imaging (B, D – F, H – I). All are in ventral view, except B and I – dorsal view, and F – posterodistal view. Scale bar 100 microns.