Paraplatyarthrus crebesconiscus Javidkar and King

Javidkar, Mohammad, King, Rachael A., Cooper, Steven J. B., Humphreys, William F. & Austin, Andrew D., 2017, Taxonomy of Paraplatyarthrus Javidkar and King (Isopoda: Oniscidea: Paraplatyarthridae) with description of five new species from Western Australia, and comments on Australian Trichorhina Budde-Lunde, 1908 (Platyarthridae), Zootaxa 4243 (3), pp. 401-431 : 409-411

Paraplatyarthrus crebesconiscus Javidkar and King , sp. nov.

Figs 5–7 , 2A , 20 B

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Type material. Holotype: Male , WAM C 54789 (BES16478.3), Halfpenny Well calcrete, Millbillillie pastoral station, Eastern Murchison region, Western Australia, Australia, 27.69661°S, 121.33953°E, Oct 2011, coll. W. F. Humphreys & S. J. B. Cooper .

Paratypes: 3 females (WAM C 54790, BES16478.2; WAM C 54791, BES16478.4; WAM C 54792, BES16478.5), 1 male ( WAM C 54793, BES16478.1) (same locality and collection data as holotype) ; 1 female (WAM C 66918, BES15072.1) (same calcrete as holotype), 27.69661°S, 121.33953°E, Mar 2009, coll. W. F. Humphreys & S.J.B. Cooper; 1 female ( WAM C 66919, BES15073), Nambi calcrete, Eastern Murchison region, Western Australia, Australia, 28.22232°S, 121.82014°E, Mar 2009, coll. W.F. Humphreys & S.J.B. Cooper ; 1 female ( WAM C 66920, BES17224.1), Laverton Downs Calcrete-Windarra , Eastern Murchison region, Western Australia, Australia, 28.50517°S, 122.18038°E, May 2012, coll. W.F. Humphreys & S.J.B. Cooper ; 1 specimen, Gender indeterminate ( WAM C 66917, BES15072) (same calcrete as holotype), 27.69661°S, 121.33953°E, Mar 2009, coll. W.F. Humphreys & S.J.B. Cooper ; 1 specimen, Gender indeterminate ( WAM C 66921, BES17224.2), Laverton Downs Calcrete-Windarra, Eastern Murchison region, Western Australia, Australia, 28.50517°S, 122.18038°E, May 2012, coll. W.F. Humphreys & S.J.B. Cooper .

Diagnosis. Eyes with 5 ommatidia. Cephalic lateral lobes not developed. Male pleopod 1 exopodite with weak posterior point.

Description. Male (WAM C 54789). Body length 2.7 mm, cephalon and posterior body weakly pigmented. Cephalic lateral lobes small. Eyes with 5 black ommatidia.

Antenna 1 with medial article shortest, distal article longest ( Fig. 5 A). Antenna 2 flagellum with basal article shorter, about 1/3 length of distal article ( Fig. 5 B).

Left mandible pars molaris ( Fig. 5 C) with 6 to 7 plumose setae; hairy lobe bearing 2 plumose setae. Right mandible pars molaris with about 6 plumose setae; 1 plumose seta on hairy lobe. Maxilla 1 outer endite ( Fig. 5 D) with outer group of 4 teeth covering about 65% of marginal area, inner group of 3 cleft teeth, 1 simple and 1 stalklike tooth; inner endite ( Fig. 5 E) with 2 very fine setae on subapical outer marginal corner. Maxilla 2 ( Fig. 5 F) apically bilobate; inner lobe comparatively smaller than outer one; inner and outer lobes delimited by fine suture. Maxillipedal endite with 1 large seta close to subapical inner corner; distal articles of palp with 1 large proximal seta, medial tuft of 2 large and 1 small setae and apical tuft of probably 2 long setae ( Fig. 5 G).

Epimeron 1 rounded anteriorly. In dorsal view, posterolateral corner of pereonites 1–4 rounded. Posterolateral corner of pereonites 5–7 posteriorly directed ( Fig. 20 B). Pleonal epimeron 5 reaching (but not surpassing) uropodal sympodite. Noduli laterales with D/C ratios not constant in tergites 1–7.

Pereopod 1 ( Fig. 6 A) carpus inner margin densely covered with long serrate setae, tuft of fine setae present medially near distal margin; propodus with both small simple and large serrate setae; dactylus with long seta not exceeding claws, outer claw relatively straight, with small depression on medial part. Pereopod 7 ( Fig. 6 B) carpus not showing any sexual dimorphism.

Pleon outline continuous with pereon. Pleopod 1 endopodite ( Fig. 7 A) slender, with simple apex, medial margin with group of fine setae, very fine setae also close to tip of endopodite; exopodite ( Fig. 7 B) heart-shaped with posterior point not developed. Genital papilla ( Fig. 6 C) ventral sheath apically pointed, surpassed by long rounded lobe. Pleopod 2 endopodite ( Fig. 7 C) with distal half slender, not reaching to posterior apex of pleopod 4 exopodite. Pleopod 2–5 exopodites ( Fig. 7 D–G) with 4 to 5 cleft and simple long setae. Pleotelson triangular and pointed. Uropodal exopodites surpassing pleotelson; endopodites slightly exceeding pleotelson; uropodal sympodite with elongated circumflex-shaped incision.

Etymology. The species name is composed of the Latin word ‘crebesco’ (meaning widespread) and ‘oniscus’, referring to its comparatively widespread distribution in the calcrete aquifers.

Remarks. Paraplatyarthrus crebesconiscus sp. nov. appears in the same clade with P. nahidae sp. nov. ( Fig. 1 ) from which it has a 12.3% COI divergence (Appendix 1). Unlike P. nahidae , the body is semi-pigmented to pale, cephalic lobes are not developed on the head, and male pleopod 1 exopodite has a weak posterior point. The body length varies between 2.7 mm and 3.5 mm. Some individuals have slightly stronger pigmentation on the dorsal body ( Fig. 2A ). It has been recorded from calcrete aquifers at Halfpenny Well (Millbillillie pastoral station), Nambi pastoral station and Laverton Downs pastoral station (Mt Windarra), and the Eastern Murchison region of Western Australia.

Figures

FIGURE 1. Maximum Likelihood (ML) tree for the mtDNA COI gene. The numbers next to the nodes are ML bootstrap values (only those greater than 50 are shown). The clade labels comprise either described new species or lineage specific codes (B or S letters) followed by the calcrete codes for undescribed species. Black and red branches (online version only) denote subterranean and surface species respectively. Abbreviations for the calcrete aquifers and some localities from Western Australia include: Calcrete areas: Laverton Downs-Windarra (LDW); Laverton Downs-Quandong (LDQ); Laverton-Shady Well (LDS); Sturt Meadows (SM); Cunyu (CUN); Lake Violet (LV); Lake Miranda East (LME); Lake Miranda West (LMW); Nambi (NAM); Uramurdah (URA); Bubble Well (BUB); Halfpenny Well (HAW); Barwidgee (BAR); Mt Morgans (MOR); Non-calcrete areas: Jorgensen Park, Kalamunda, WA (JP); Gooseberry Hills, WA (GOO); Wooroloo, WA (WOO); Moorapulling Rd., Marradong, WA (MOO).

FIGURE 2. A: P. crebesconiscus sp. nov.; B & C: P. cunyuensis sp. nov., the arrow shows the cephalic lateral lobe; D: P. nahidae sp. nov.; E & F: P. occidentoniscus sp. nov., the arrow shows the cephalic lateral lobe; G: P. pallidus sp. nov.; H: P. subterraneus; scale bar of the image c: 0.5 mm, scale bar in other images: 1 mm. All images are of paratype specimens.

FIGURE 5. Paraplatyarthrus crebesconiscus sp. nov., (Holotype, ♂), A, antenna 1; B, antenna 2; C, left mandible; D, maxilla 1 outer endite; E, maxilla 1 inner endite; F, maxilla 2; G, maxilliped. Scale bars: 0.1 mm.

FIGURE 6. Paraplatyarthrus crebesconiscus sp. nov., (Holotype, ♂), A, pereopod 1; B, pereopod 7; C, genital papilla. Scale bars: 0.1 mm.

FIGURE 7. Paraplatyarthrus crebesconiscus sp. nov., (Holotype, ♂), A, pleopod 1 endopodite; B, pleopod 1 exopodite; C, pleopod 2 endopodite; D, pleopod 2 exopodite; E, pleopod 3 exopodite; F, pleopod 4 exopodite; G, pleopod 5 exopodite. Scale bars: 0.1 mm.

FIGURE 20. The position of posterolateral corner (PLC) of epimera 1 to 7 in dorsal view; Type A, PLC in pereonal epimera 1 – 3 rounded, in 4 – 7 posteriorly directed; Type B, PLC in pereonal epimera 1 – 4 rounded, in 5 – 7 posteriorly directed.