Caulleriella eltaninae Blake 2018, new species

Caulleriella eltaninae new species

Figure 22

Caulleriella aff. zetlandica: Hartmann-Schröder & Rosenfeldt, 1989: 66–67, figs. 1–2. Not McIntosh 1911.

Material Examined. Antarctic Peninsula, NE of Joinville Island: USNS Eltanin Cr. 12, Sta. 1003, 15 Mar 1964, 62.68°S, 54.72°W, trawl, 210–220 m, holotype (USNM 1013888).— South Shetland Islands, NE of Clarence

Island, USNS Eltanin Cr. 12, Sta. 1089, 17 Apr 1964, 60.78°S, 53.50°W, trawl, 641m, paratype (USNM 1013889).— Ross Sea, off Victoria Land, USNS Eltanin Cr. 32, Sta. 2005, 73.033°S, 176.857°E, trawl, 864–874 m, paratype (USNM 1013890).

Description. A moderately sized species, holotype complete but in two pieces, 9.5 mm long, 0.5 mm wide for approximately 145 setigers. Body generally thick throughout, anterior segments widest, narrowing in posterior setigers. Individual segments always wider than long. Ventral groove present for entire length of body (Fig. 22A). Color in alcohol: light tan to brown, without pigment.

Prostomium short, triangular, rounded on anterior margin (Fig. 22 A–B); one paratype with a single small faded eyespot on dorsolateral surface, otherwise eyespots not apparent; nuchal organs not observed. Peristomium longer than wide, tapering anteriorly, divided into three rings by weak grooves, best seen laterally (Fig. 22 A–B); dorsal surface smooth, crest absent. Peristomium followed by narrow achaetous segment from which dorsal tentacles arise from wide laterally spaced locations (Fig. 22A); tentacle scars large, wider than long. First pair of branchiae on posterior border of setiger 1, subsequent branchiae in similar position dorsal to notosetae continuing through middle segments (Fig. 22B).

Noto- and neuropodia well developed, widely separated as typical for Caulleriella species (Fig. 22A). Notopodia set off from elevated domed dorsal surface by grooves; neuropodia with setae directed toward midventral groove.

Notosetae all capillaries, with 8–10 long setae per fascicle in anterior setigers, reduced to 3–5 in middle and posterior setigers. Neurosetae of setigers 1–19 or 20 with capillaries similar to those of notopodia; 2–3 curved bidentate hooks first present from setiger 19–21, accompanied by 3–4 capillaries, hooks increasing to 6–7 over following setigers; capillaries reduced to 1–2 thin setae, usually in superior position for remaining setigers; hooks arranged in single row with teeth directed ventrally toward mid-ventral groove. Hooks with blunt, thick main fang and thinner, more pointed apical tooth (Fig. 22D); hood or sheath not apparent.

Pygidium with at least one short ventral cirrus apparent on holotype (Fig. 22C); anus surrounded by several short papillae.

Etymology. This species is named for the USNS Eltanin, former research vessel of the United States Antarctic Research Program.

Remarks. Caulleriella eltaninae n. sp. joins C. fucata n. sp., its Antarctic congener, in having bidentate hooks limited to neuropodia. Other species currently referred to Caulleriella have hooks in both noto- and neuropodia. Caulleriella eltaninae n. sp. differs from C. fucata n. sp. in lacking distinctive pigment markings, in having neuropodial hooks first present from setigers 20–21 instead of 5–6, in having these same hooks accompanied by a few capillaries throughout instead of lacking capillaries entirely, and by having an anal cirrus instead of lacking one. Caulleriella aff. zetlandica reported by Hartmann-Schröder & Rosenfeldt (1989) from the Antarctic Peninsula is likely this species.

Distribution. Antarctic Peninsula, South Shetland Islands; Ross Sea, Victoria Land; 210– 870 m.