Neastacilla antipodea Poore, 1981

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 : 375-376

Neastacilla antipodea Poore

Neastacilla antipodea Poore, 1981: 333 , figs 2–3.

Material examined. New Zealand: NMV J679 (1 male, 1 female) .

Description of female. Head without dorsal elevation, anterolateral lobes rounded, rostral point absent; lateral margin of head and pereonite 1 incised. Pereonite 1 without lateral extension, with dorsal elevation. Pereonites 2 and 3 progressively wider; with distinct keel-like dorsal elevations, bilobed lateral extensions visible on dorsal view. Pereonite 4 about 5 times as long as pereonite 3, with single keel-like anterior dorsal elevation, anterolateral and posterolateral margins extended, forming a square shape in dorsal view. Peronites 5–7 progressively shorter posteriorly; without dorsal elevations. Pleon length subequal to the combined lengths of pereonites 5–7, without dorsal elevations, without lateral wings, apex bluntly rounded.

Eyes small and oval. Antenna 1 reaching to second peduncular article of antenna 2; aesthetascs present distally on flagellum. Antenna 2 robust, more than half as long as body; flagellum of 3 articles, ending with claw, row of scales along full length.

Maxilla 1 mesial lobe with 3 plumose terminal setae; lateral lobe with 11 distal robust setae. Maxilla 2 mesial lobe with about 20 plumose setae; middle lobe with 6 setae; lateral lobe with 3 setae. Maxillipedal endite with numerous mesial setae, 2 coupling hooks; palp article 2 with mesial setal rows; articles 3 and 4 with mesial and lateral setal rows; article 5 with mesial and distal setae.

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

Adult: 7.0–8.0 mm, juveniles 3.0–7.0 mm, mancas 2.0–3.0 mm

Male. Pereonite 1 without lateral extensions, without dorsal elevation. Pereonites 2 and 3 progressively wider; without distinct dorsal elevations, without lateral extensions. Pereonite 4 about 5 times as long as pereonite 3, without dorsal elevation, anterolateral and posterolateral margins not extended. Peronites 5–7 progressively shorter posteriorly, without dorsal elevations. Pleon length subequal to the combined lengths of pereonites 5–7, without dorsal elevations, without lateral wings, apex bluntly rounded.

Antennae, mouthparts, pereopods and uropods as for female.

Pleopod 1 exopod with lateral notch and 2 plumose lateral setae. Pleopod 2 appendix masculina with ridge on posterior face, curved, extending twice as long as the endopod, apex simple. Penial plate widened proximally, distally bulbous, apex acute.

Adult: 7.3–8.5 mm, juveniles 3.0–7.0 mm, mancas 2.0–3.0 mm.

Distribution. New Zealand: The Snares; intertidal to 15 m depth.

Remarks. Neastacilla antipodea is one of five species of Neastacilla ( N. fusiformis , N. tuberculata , N. levis , N. tattersalli ) known from New Zealand. The ornamentation of N. antipodea distinguishes it from all the other species immediately: specifically, the bluntly rounded pleon and the square shape of pereonite 4 of the female in dorsal view.