Neastacilla lawadi, King, 2003

King, R. A., 2003, Neastacilla Tattersall, 1921 redefined, with eight new species from Australia (Crustacea: Isopoda: Arcturidae), Memoirs of Museum Victoria 60 (2), pp. 371-416 : 390

Neastacilla lawadi sp. nov.

Figures 12–13

Material examined. Holotype. Australia: WA, between Dampier and Port Hedland, 19º48.8'S, 117º52.2'E, 52 m, 2 Sep 1983, NMV J16933 (1 female, 8 mm).

Paratypes Australia: NT. Oxley Island , (W side) , 11º00.0'S, 132º49.0'E, 14 m, 21 Oct 1982, NMV J16580 (2 females, 5 mm). NT, station unknown , Oct 1982, NMV J16581 (1 female, 9 mm; 1 male, 6 mm). SA. upper Spencer Gulf , NMV J16614 (1 female, 7.5 mm); E of Lowly Point , 33º00.0'S, 137º49.5'E, 18 m, Feb 1986, NMV J16610 (1 female, 7.5 mm); N of Fairway Bank , 33º02.4'S, 137º45.0'E, 18 m, Feb 1986, J16611 (1 female, 8 mm). WA. Between Dampier and Port Hedland , 19º37.00'S, 118º53.00'E, 30 m, 3 Jun 1983, NMV J16634 (1 male, 5.5 mm) ; 19º05.82S, 118º56.7'E, 82 m, 14 Feb 1983, NMV J16669 (3 females, 7.5–8.5 mm; damaged juvenile 5.5 mm; manca 1 3.5 mm) ; 19º48.8'S, 117º52.2'E, 52 m, 2 Sep 1983, NMV J16660 (1 female 7.5 mm) ; 19º29.0'S, 118º53.2'E, 40 m, 12 Feb 1983, NMV 16931 (1 female 7.5 mm) ; 19º37.0'S, 118º53.0'E, 30 m, 3 Jun 1983, NMV 16634 (3 mature females, 5–6.5 mm; 2 immature females, 5 mm; 1 male, 5 mm) .

Description of female. Head with 2 large dorsal elevations and 2 small elevations posteriorly; anterolateral margins angular; rostral point present; lateral margin of head and pereonite 1 not incised. Head and pereonite 1 extended anterolaterally. Pereonite 1 with small paired tuberculate dorsal elevations. Pereonites 2 and 3 with small paired tuberculate dorsal elevations and lateral tuberculate elevations, small lateral extensions present. Pereonite 4 about 9 times as long as pereonite 3, with dorsal and dorsolateral tuberculate elevations anteriorly, large paired dorsal elevations midlength, anterolateral margins rounded and extended. Pereonites 5–7 progressively smaller posteriorly, with some dorsal tuberculation. Pleon length greater than combined lengths of pereonites 5–7, with 2 sets of lateral wings, apex subacute.

Eyes small and suboval. Antenna 1 extending to midlength of third peduncular article of antenna 2; aesthetascs present distally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 2 articles ending with a claw, with row of scales along full length.

Maxilla 1 with 3 terminal setae; lateral lobe with 10 distal robust setae. Maxilla 2 mesial lobe with 22 plumose setae, middle lobe with 3 setae, lateral lobe with 3 setae. Maxillipedal endite with 12 mesial setae; 1 coupling hook; palp article 2 with mesial setal rows, articles 3 and 4 with mesial and lateral setal rows, article 5 with distal setae.

Pereopod 1 propodus slightly shorter than carpus; dactylus longer than wide, without unguis. Pereopods 2–4 with small dactylus. Pereopods 5–7 dactylus not denticulate, with unguis and secondary unguis; secondary unguis setiform and slender and only slightly smaller than primary unguis. Uropodal exopod with 2 setae of equal length. Oostegite 4 with a sutured small posterior lobe.

5–9 mm.

Male. Ornamentation not as pronounced as for female. Head with slight elevation and pereonites 1 to 3 with some tuberculation. Pereonite 4 about 10 times as long as pereonite 3; without dorsal elevations except for posterodorsal curved elevation. Pereonites 5–7 progressively smaller; pereonite 5 with a dorsal curved elevation; pereonites 6 and 7 without dorsal elevations. Pleon longer than combined lengths of pereonites 5–7, with 2 sets of lateral wings, apex subacute.

Antennae, mouthparts, pereopods and uropods as for female.

Pleopod 1 exopod with lateral notch and 2 plumose setae of unequal length. Pleopod 2 appendix masculina with ridge on posterior face, curved, extending third length past endopod, apex simple. Penial plate widened proximally, distally tapered, apex simple.

5–7 mm.

Distribution. Australia: Western Australia, Northern Territory, South Australia; subtidal to 82 m depth.

Etymology. “Lawadi ” is an Australian Aboriginal word in the Gooniyandi dialect from north-western Australia where this species was first collected. It means “shoulder” and refers to the rounded anterolateral extensions on pereonite 4 of the female.

Remarks. This species resembles Neastacilla attenuata Hale, 1946 from New South Wales and the eastern coasts of Australia. However, the shape of the head is the most obvious difference between the two. N. lawadi sp. nov. does not have a lateral incision between the head and pereonite 1 and the head is more ventrally expanded and more sculptured. The third peduncular article of antenna 2 in N. lawadi sp. nov. is not thickened as in N. attenuata . The pleotelson of N. lawadi sp. nov. has a posterior dorsal elevation and more pronounced lateral wings. Neastacilla attenuata has a slender pleotelson with no elevation and is slightly turned up at the end.

Figures

Figure 12. Neastacilla lawadi sp. nov., female holotype (NMV J16933): A, lateral view; B, dorsal view; A1, A2, left MXP, MX1, MX2, MD. Male (NMV J16634): C, ventral view; D, dorsal view; A1. Scale: a (A–D) = 1.0 mm; b (A1, A1) = 0.5 mm; c (A2) = 1.0 mm; d (MXP, MX1, MX2, MD) = 0.5 mm.

Figure 13. Neastacilla lawadi sp. nov., female holotype (NMV J16933): P1, P3, P5, U, A, ventral view. Scales: a (P1, P3) = 0.5 mm; b (P5) = 0.5 mm; c (Pl1, PL2, Pe, U) = 0.5 mm; d (A) = 1.0 mm.