Pygolabis gascoyne, 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 : 22-26

Pygolabis gascoyne sp. nov. ( Figs 12–13 )

Etymology. The name of this species, treated as a noun in apposition, is drawn from the Gascoyne region of Western Australia, where Wanna Station is located.

Type material. Western Australia: Gascoyne region: Holotype male, body length 10 mm, Wanna Station, bore at StoneTank Well, 23°56.3'S 116°29.5'E, fld. no. BES 8835, 14 iv 2003 (W.F. Humphreys, R. Leijs) preserved in 100% ethanol ( WAM C34953). Paratypes: female, body length 9.8 mm, same data as holotype except fld. no. BES 8836 preserved in 75% "special meths" (AM P70421).

Diagnosis. Pleotelson. Distance between uropod insertions and apex subequal to 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 truncate, posterior margin indentation present. 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 subequal to lateral teeth in middle of ridge; lateral margin not distinctly projecting — forming smoothly rounded arc; distal tip with broad cup; medial distal margin angular. Uropods. Protopod extending beyond pleotelson apex.

Description. Head. Length 0.59 width, 1.15 pereonite 1 medial length; clypeus proximal width 0.48 head width.

Pereonites. Total medial length 0.52 body length; medially 3–5 subequal and longest, 2 and 6 shorter and subequal, 7 shorter than 6.

Pleonites. 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, 0.06, 0.05, 0.07.

Pleotelson. Medial length 1.29 width, 0.55 pleon length; distance between uropod insertions and apex 0.48 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 1.26 distance from uropod insertions to lateral inflection points of posterior margin; posterolateral margins with 28 small non­sensillate simple setae (approximately).

Antennula . Length 0.23 body length; with 20 articles; article 2 subequal to article 1, article 3 shorter than article 1.

Antenna. 0.44 body length; with 32–38 articles (32 right side, 38 left side). Flagellum length 0.76 antenna total length.

Pereopods. Pereopods 1–7 respective lengths: body length — 0.14, 0.24, 0.23, 0.19, 0.21, 0.22, 0.24. Pereopod 1 propodus and carpus with robust bidenticulate sensillate setae, respectively 7, 1. Pereopods 2–3 carpus with 18, 19 robust sensillate setae respectively, lateral row with 9 robust setae.

Pleopods. Pleopod 2 male endopod appendix masculina length 0.91 distance from base of appendix masculina to distal margin of exopod; lateral margin with 18 teeth, including 4 distal elongate spine­like teeth; distal segment length 1.29 width.

Uropods. Length 0.13 body length, 0.44 pleon length. Protopod length between insertion and distal margin 1.11 length between insertion and pleotelson apex; with 12 small tooth­like setae along medial margin. Endopod length 0.58 protopod length, 1.16 exopod length; medial margin with proximal and distal penicillate setae, with 7 small tooth­like setae (placed proximally and distally). Exopod length 0.5 protopod length.

Remarks. Pygolabis gascoyne is most similar to P. humphreysi and P. paraburdoo . It differs from P. humphreysi in having a truncate indented pleotelson apex (compared to rounded and entire) and an appendix masculina with the distal medial margin angular (compared to rounded). Pygolabis gascoyne differs from P. paraburdoo in having the appendix masculina with teeth on the distal lateral margin not distinctly separated (compared to distinctly separated for more than half of the distance in which they occur) and the medial distal margin angular (compared to rounded).

Distribution. Stone Tank Well, Wanna Station, Gascoyne Region, 23°56.3'S 116°29.5'E, Western Australia.

Figures

FIGURE 12. P. gascoyne sp. nov. Holotype male (WAM C 34953). Bold arrow showing indentation on tip of pleotelson. Scale bar 1 mm.

FIGURE 13. P. gascoyne sp. nov. Holotype male (WAM C 34953). Scale bar 0.5 mm.