Omphalopomopsis langerhansii (Marenzeller, 1885)

Figures 2 (C and D), 4 (A–M) and 5 (A–F)

Omphalopoma langerhansii Marenzeller, 1885: 219 –220, pl. IV, fig. 6.

Omphalopomopsis langerhansii— ten Hove & Kupriyanova, 2009: 69, fig. 7a, b.

Material examined. Cross Seamount, Hawaii, “Moana Wave” cruise leg 13, dredge haul 2, 18 °47.52’N 158°13.73’W, HURL, 12/16/1981, 2,013 m (1, USNM 1156951; 1, BPBM R3558).

Description. TUBE: Tubes white, opaque, length 10–20 mm, width 2–3 mm; oldest part triangular in crosssection, with delicate flaring mouth, becoming round in section towards the mouth (Figs. 2 C, 4A–C). Median keel of fine denticulate spines present (Figs. 2 C, 4A, B) and projecting over the mouth; 2–3 rows of lateral spines, most numerous towards the mouth. Flared rims of earlier tube mouths evident as transverse raised flanges (Fig. 4 C).

BRANCHIAE: Branchial crown with 10–12 radioles on either side, the second on the left side with operculum in both specimens.

PEDUNCLE: Opercular peduncle arises as the second filament on the left side and lies across the first and third normal radioles; oval and slightly flattened in cross-section.

OPERCULUM: Operculum with vesicular ampulla and a lightly calcified flat plate with slightly upturned rim and a convex center (Figs. 2 D, 4D, E). Two small swellings (not wings) present where the ampulla joins the opercular stalk (Figs. 4 D, E), the distal latero-dorsal “winglets” sensu ten Hove & Kupriyanova (2009: 22).

COLLAR and thoracic membranes: Collar trilobed. Thoracic membrane best developed anteriorly extending beyond last thoracic chaetiger; apron absent. Tonguelets not observed.

THORAX: Seven thoracic chaetigers, six uncinigerous. Uncinigerous rows of second chaetiger shorter and more widely spaced than subsequent chaetigers. Collar chaetae slender finely denticulate bayonet-like (Figs. 4 F; 5A, B) and narrowly limbate capillaries with long blades (Fig. 4 G). Chaetae of chaetigers 2–7 with simple blade. Apomatus chaetae observed from chaetiger 3 (Fig. 4 H). Thoracic uncini saw-shaped with simple rounded anterior fang and 8–9 teeth (Figs. 4 I, J; 5C). Uncini with 8 and 9 teeth in the same uncinigerous torus.

ABDOMEN: Abdominal chaetae of 2 types, anterior chaetigers with narrow flat geniculate chaetae (Figs. 4 K; 5D) and posterior chaetigers with a few geniculate chaetae and long tapered capillaries with denticulate tip (Figs. 4 L; 5E). Abdominal uncini rasp-shaped, smaller than thoracic ones, with 8–9 rows of teeth and a rounded anterior fang (Figs. 4 M; 5F).

Remarks. One specimen with a large round, multilocular foraminiferan lodged in the intestine. Specimens fit well the generic description and illustrations by ten Hove & Kupriyanova (2009). These specimens appear to be a new and deeper record for Omphalopomopsis langerhansii, which is known from a single specimen collected from Enoshima in South Japan at 366 m (ten Hove and Kupriyanova, 2009).

Distribution. Enoshima, South Japan and newly recorded to Cross Seamount in the Hawaiian Chain; 2,013 m attached to small pieces of rock.