Harmothoe ingolfiana Ditlevsen 1917

Harmothoe ingolfiana Ditlevsen, 1917

(Figs. 1; 24A–H)

Harmothoe ingolfiana Ditlevsen, 1917: 32, pl. 1 figs. 12–14, pl. 2 fig. 15, textfig.s. 14–15; Wesenberg-Lund (1950): 8; Pettibone (1985): 143, fig. 5.

Type material. Harmothoe ingolfiana: 10 syntypes (5 cs, 5 af, 2 pf), ZMUC-POL-1316; "Ingolf" St. 67; S of Iceland; 61°30'N 22°30'W; 1836 m.

Diagnosis. Without eyes. Elytral margin and surface with scattered, short papillae; microtubercles conical or spine-shaped or cylindrical with bi- or multifid tip; macrotubercles near posterior margin, drop-shaped or cylindrical with smooth or nodular surface.

Description (based on largest complete syntype).

Body with 36 segments. At anterior end (Fig. 24A), prostomium bilobed, with rather prominent cephalic peaks; ceratophore of median antenna in anterior notch, lateral antennae inserted ventrally, styles of antennae papillate, tapering; eyes absent (also in other investigated syntypes); palps papillate, tapering.

Tentaculophores inserted laterally to prostomium, each with two notochaetae and a dorsal and ventral tentacular cirrus, styles of cirri papillate, tapering. Second segment with first pair of elytra, biramous parapodia, and long buccal cirri. Following segments with tapering, short ventral cirri.

Fifteen pairs of elytra, covering dorsum, on segments 2, 4, 5, 7, then on every second segment to 23, 26, 29, 32; last four segments cirrigerous; elytral margin and surface with scattered, short papillae; microtubercles larger towards posterior margin, conical or spine-shaped or cylindrical with bi- or multifid tip; macrotubercles near posterior margin, drop-shaped or cylindrical with smooth or nodular surface (Fig. 24B–D). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, style papillate, tapering.

Parapodia biramous; notopodia with elongate acicular lobe; neuropodia with elongate prechaetal acicular lobe with very short supra-acicular process; neuropodial postchaetal lobe shorter than prechaetal lobe, rounded; tips of noto- and neuroacicula penetrating epidermis (Fig. 24E). Notochaetae stouter than neurochaetae; with distinct rows of spines and blunt to tapering tip (Fig. 24F); neurochaetae with distinct rows of spines and mostly with bidentate tip with stout to slender secondary tooth, some upper and lower unidentate (Fig. 24G,H).

Measurements. Largest syntype, ZMUC-POL-1316 (Fig. 24A–H): L 14 mm, W 4 mm for 36 segments.

Distribution. North Atlantic, S of Iceland to off New England.

Habitat. In burrows of wood-boring bivalves, in 1830 to 3506 m.