Terebellides

Terebellides sp. C

Figs 25, 26

Material examined: DZMB-HH 6075, ANDEEP I St. 46-3, GKG (ZMH-26014)

Description:

Single individual 20 mm in length, 1.7 mm in width, complete with 18 thoracic chaetigers and 29 abdominal uncinigers.

Head region: Tentacular membrane compact, not largely expanded, small compared to lower lip, with reddish dots at its base (Fig. 25 A). Lower lip rectangular, slightly expanded. Tentacles short simple ones on outer margins of tentacular membrane and few longer ones with expanded tips present (Figs 25 B, 26A, C–E).

Branchiae: Three branchial lobes present, all of similar length, free from each other, lamellae broad, but compactly packed, distinctly triangular in shape, with filamentous tips (Fig. 25 A, C). Fifth branchial lobe absent. Annulation of branchial stem present.

Anterior chaetigers: First chaetiger’s notopodia reduced in size with chaetae more or less originating from body wall. Subsequent notopodia very elongate with pre and post chaetal lobes equal in length. Geniculate hooks: Present on TC-6 (segment 8) only. About 8 per side, sharply bent.

Lateral lappets: Distinct, present from TC-1–6, with TC-1=2=3>4=5=6 (Fig. 26 A, C).

Ventral pads: Chaetigers 1–3 with large ventral pads with elevated anterior margins appearing slightly crenulated. Following two chaetigers, 4 and 5 much narrower, with anterior margins not elevated. Subsequent thoracic chaetigers wider and less glandular than 1–3, without elevated anterior margins.

Nephridial papillae: Possibly present in segments 3, 6, 7.

MG staining pattern: Very conspicuous (Figs 25 D, E, 26). Solid to TC4, then striped to about TC-10/-11, glandular fields lateral on TC-1, -2 & -3, largest in TC-3, smallest in TC-1. Anterior margins of TC-1–4 darker stained than others, possibly with a white band in TC-1. Noto- and neuropoda stain as well. Abdominal segments with lateral stripes through the parapodia giving the abdomen a zebra-like appearance. Pygidium papillae brightly stained.

Pygidium: 2 lateral papillae.

Remarks: This species differs from all species described from the region by its very conspicuous methyl green staining. It also possesses a tentacular membrane which is relatively small and small, branchial lamellae that are triangular in cross-section.

Habitat: Drake Passage, in 2888 m.