Naineris antarctica Blake, 2017, new species

Naineris antarctica new species

Figures 52–53

Haploscoloplos kerguelensis: Hartman 1978: 156 (in part, Sta. 69-1). Not McIntosh 1885.

Material examined. Weddell Sea, Glacier Sta. 69-1, 512 m (2, USNM 46604). — Ross Sea, East of Cape Adare, Eltanin Sta. 32-1995, 10 Jan 1968, 72.05°S, 172.63°E, 344–348 m, holotype and 3 paratypes (USNM 690405–6); N. of Ross Island, Eltanin Sta. 32-2050, 22 Jan 1968, 77.03° S, 168.50° E, 909–923 m, 1 paratype (USNM 1013906); Ross Sea, Moubray Bay, off Cape Hallett, Deep Freeze IV, Northwind Sta. 8, 12 Jan 1959, 72.288°S, 170.300°E, 135 m, 1 paratype (USNM 1013907).

Description. A small species, holotype complete, 7.5 mm long and 0.75 mm wide for 50 setigers. Thoracic region with 9–10 setigers; transition from thorax to abdomen generally abrupt, with last 1–2 thoracic setigers having fewer neuropodial uncini. Branchiae from setiger 6–7 continuing to posterior end of body (Fig. 52 A–B). Anus terminal, located between two rounded lobes, each bearing thin anal cirrus (Fig. 52 B).

Prostomium weakly pear-shaped, smoothly rounded on anterior margin (Figs. 52 A, 53A), no eyespots; paired nuchal organs at margin of prostomium and peristomium (Fig. 53 A, inset). Peristomium with two achaetous rings (Figs. 52 A, 53A).

Notopodia with elongated postsetal lobes throughout body, with those of first few thoracic and last abdominal segments shortest (Figs. 52 A–B, 53A). Thoracic neuropodia swollen, forming rounded tori from which setae emerge (Fig. 52 C); postsetal lobes first present from setiger 6, continuing to abdominal region. Abdominal neuropodia elongate, rounded apically, with short ventral cirrus (Figs. 52 D, 53D).

Thoracic notosetae including crenulated capillaries and shorter, non-capillary tipped, but sharply pointed setae (Fig. 52 E), and furcate setae. Abdominal notosetae including pointed setae, 1–2 heavy, smooth acicular spines (Fig. 52 D, F) and furcate setae; furcate setae with unequal tynes bearing thin needles between tynes (Fig. 52 G); in SEM tynes with entire narrow tips with 4–5 needles on either side merging with tynes (Fig. 53 E–F), shafts with few irregular barbs, otherwise smooth. Thoracic neurosetae including crenulated capillaries and ribbed uncini arranged in two rows (Figs. 52 C, H, 53C); depression or notch visible on concave curvature of spine in light microscopy, with evidence of lateral ribs on some spines, shaft generally appearing smooth (Fig. 52 H); with SEM concave side of curved apex flattened, only weakly notched, shaft with transverse rows of barbs continuing from posterior of curved apex to emergence from neuropodium (Fig. 53 C). Abdominal neurosetae including a few capillaries setae and 1–2 strongly curved acicular spines (Figs. 52 I, 53B, D).

Etymology. The species is named for Antarctica, because it is the only species of the genus known from the Southern continent.

Remarks. Naineris antarctica n. sp. differs from other species of the genus in having heavy acicular spines in abdominal notopodia which, with the strongly curved neuropodial aciculae provide a striking armature to the abdominal region. The paratypes from Eltanin Sta. 2050 have a somewhat more conical prostomium than the other specimens, but otherwise agree in all other respects.

Distribution. Antarctica, Weddell and Ross Seas, 344– 923 m.