Neastacilla tuberculata (Thomson)

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 : 409

Neastacilla tuberculata (Thomson)

Figures 28–29

Arcturus tuberculatus Thomson, 1879: 416–417 , pl. 19 figs 1–4.— Thomson, 1881: 206, pl. 7 fig. 2.— Thomson and Chilton, 1886: 156.— Filhol, 1885, 437. (not Arcturus tuberculatus Latreille, 1829 , junior synonym of Arcturus baffini Sabine ).

Astacilla tuberculata . — Hurley, 1961: 264.

Neastacilla tuberculata . — Poore, 1981: 333.

Material examined. New Zealand: Lyttelton Harbour , 5 m, Aug 1997, NMV J40643 (1 male, 4.5 mm) . Otago Harbour , 12.1 m, 4 Oct 1965, NMV J16559 (1 female, 4.5 mm), NMV J16560 (1 male, 4 mm), NMV J16558 (1 female, 5 mm) NMV J16562 (1 male, 5 mm) . Otago Harbour , 6 m, 18 Jun 1965, NMV J 16560 (3 females, 4–4.5 mm; 5 males, 3.5–5 mm; 2 juveniles, 3 mm) . Otago Harbour , 13 m, 30 Apr 1965, NMV J16561 (1 male, 5 mm) . Otago Harbour , 13 m, 4 Oct 1965, NMV J16556 (1 female, 5 mm) . Otago Harbour , 4.1 m, 13 Jun 1965, NMV J12927 (1 female, 4 mm) . Otago Harbour , 2.9 m, 7 Jan 1967, NMV J40644 (1 female, 4.5 mm). The Snares, 146 m, 26 Nov 1974, NMV J16557 (1 male, 4.5 mm) .

Description of female. Head with 2 dorsal elevations between eyes, small dorsal elevation in front of eyes and an elevation posterior to eyes on dorsal midline, anterolateral margins angular, rostral point absent. Lateral margin of head and pereonite 1 not incised. Pereonite 1 with 2 elevations along dorsal line and pair of dorsolateral elevations. Pereonites 2 and 3 progressively wider; with dorsal and dorsolateral elevations, anterolateral margins extended. Pereonite 4 about 7 times as long as pereonite 3, with a large dorsal elevation (with 3 apices) covering the first two-thirds length, small anterior dorsolateral elevations,dorsolateral elevations at midlength, a posterodorsal elevation on the dorsal line and 2 small dorsolateral elevations posterior to that, with anterolateral margins rounded and extended. Pereonites 5–7 progressively smaller, with small dorsal and dorsolateral elevations, lateral margin extended. Pleon longer than combined lengths of pereonites 5–7, with 2 sets of lateral wings, with small dorsal and dorsolateral elevations, flared posteriorly and tapering to acute apex.

Eyes small and round. Antenna 1 reaching to the end of third peduncular article of antenna 2; aesthetascs attached laterally and distally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 3 articles and claw, with row of scales along full length.

Maxilla 1 inner lobe with 3 terminal setae; outer lobe with 10 distal robust setae. Maxilla 2 inner lobe with 18 plumose setae, middle lobe with 3 setae, outer lobe with 3 setae. Maxillipedal endite with 14 mesial setae; 1 coupling hook; palp article 2 with mesial setal rows, article 3 with mesial and lateral setal rows, article 4 with mesial setae, article 5 with mesial and distal setae.

Pereopod 1 propodus as long as carpus; dactylus slightly longer than wide, without unguis. Pereopods 2–4 with small dactylus. Pereopods 5–7 progressively smaller; dactylus denticulate, with unguis and secondary unguis; secondary unguis half length of primary unguis. Uropodal exopod with 2 setae of subequal length. Oostegite 4 with sutured small posterior lobe.

4–5 mm.

Male. With less ornamentation than female. Head with 2 dorsal elevations (sometimes fused) between eyes; anterolateral margins angular; rostral point absent; lateral margin of head and pereonite 1 not incised. Pereonite 1 with small dorsal and dorsolateral elevations. Pereonite 2 and 3 with dorsal and dorsolateral elevations. Pereonite 4 about 6 times as long as pereo-nite 3; with an anterior dorsal elevation at third length, a small posterior dorsal elevation and 2 small posterior dorsolateral elevations. Pereonites 5–7 progressively smaller without distinct dorsal elevations except for pereonite 5 which has a small posterior dorsal elevation. Pleon longer than combined lengths of pereonites 5–7, with 2 sets of lateral wings, with small dorsal elevations, tapering to an acute apex.

Antennae, mouthparts, pereopods and uropods as for female.

Pleopod 1 exopod with lateral notch and 2 plumose lateral setae of equal length. Pleopod 2 appendix masculina with ridge on posterior face; curved; extending more than third length past the endopod; apex tapered. Penial plate simple and straight.

3.5–5.0 mm.

Distribution. New Zealand; subtidal to 201 m depth.

Remarks. This species was briefly described by Thomson (1879) who illustrated only the lateral view of a female. The highly ornamented body, particularly the dorsally elevated pereonite 4, makes it distinguishable from other New Zealand arcturids.

Figures

Figure 28. Neastacilla tuberculata (Thomson, 1879), female (NMV J16559): A, lateral view; B, dorsal view; A1, A2, antenna 2. Male (NMV J16560): C, lateral view; D, dorsal view. Scales = a (A–D) = 1.0 mm; b (A2) = 0.5 mm; c (A1) = 0.5 mm.

Figure 29. Neastacilla tuberculata (Thomson, 1879), female (NMV J16559): P1, P3, P5, U. Male (NMV J16560): PL1, PL2, Pe Scales: a (P1, P3) = 0.5 mm; b (P5) = 0.5 mm; c (PL1, PL2, Pe) = 0.5 mm.