Figs. 8, 9
Careproctus polarsterni Duhamel 1992:188, Fig. 3; Andriashev 1994:317, Figs. 1–3; Andriashev & Stein 1998:38, Fig. 22; Andriashev 2003:162, Figs. 83, 84.
Holotype. MNHN 1991–357, adult female, 51.9 mm SL, 74°37'03" S, 29°38'02" W, Halley Bay, Weddell Sea, R / V Polarstern, Stn 249 GSN 11, 4 Feb. 1989, 701– 702 m.
Material examined. LACM 11103–1, female, ~ 52 mm TL, 45 mm SL, 73°50' S, 178°14' E, Ross Sea, USNS Eltanin, Stn. 2021, 15 Jan. 1968, 495– 503 m.
Expanded diagnosis. Counts. V 51–55 (8–9+43–46), D 47–50, A 41–45, C 10 (1+4/5), P 26–31 (20–23+6–8), radials 3 (2+0+1), pc 4–6, pores 2–5–7–1. Ratios. HL 25.9–28.0, HW 16–19, E 6.5–7.1, io 9.2–9.5, go 6.7–7.9, md 11.4–12.3, disk 7.9–9.8, da 3.1–3.5, bd 20.3–21.9, preA 35.5–39.1, ma 23.8–26.6, aAf 11.4–13.8, UPL 21.3–23.8, LPL 21.6–23.8. In % HL: E 25.0–25.8, orbit ~27, go 26–28, da 12.0–13.5, UPL 77–85, LPL 77–85.
Head moderately large, broad. Snout high, blunt. Mouth terminal, upper jaw extending to below anterior of pupil, oral cleft below anterior edge of eye. Teeth very small, simple, in oblique rows forming moderately wide bands; symphyseal gap absent in both jaws. Circumoral pores large, distinct; upper preopercular pore, postorbital, and suprabranchial pores small. Symphyseal pore pair small, opening in one common oval pore. Gill opening above pectoral fin and in front of 1–3 rays, less than 10% SL. Gill flap sharply lobed, its tip extending to behind pectoral base. Anterior lobe of disk almost absent, slightly convex. Pectoral fin with 26–31 (20–23+6–8) rays; upper lobe short; notch moderately deep, notch rays indistinct from upper lobe rays, none rudimentary; lower lobe about as long as or slightly longer than upper lobe, distinct, its most ventral ray well anterior, below pupil of eye. Radials small, round. Scapula without helve, hemicircular; coracoid with long triangular helve aligned with girdle rather than pointing anteriorly, basal notch absent. Pleural ribs absent. Hypural plate single, unslit. Body pale, orobranchial cavity gray, peritoneum black, visible through body wall, stomach pale.
Distribution. Circumantarctic, known from the Weddell Sea, Princess Martha Coast, and the northern Ross Sea at 495– 830 m.
Comparisons. Careproctus polarsterni differs from other ribless Antarctic species in having a single chin pore. In this character it is similar to C. cactiformis Andriashev 1990b and C. acaecus Andriashev 1991c from Patagonia, but both of them have fewer vertebrae (46–47 vs 51–55), a pale peritoneum (vs dark), and a scapular helve (vs absent).