Terebellides

Schüller, Myriam & Hutchings, Pat, 2013, New species of Terebellides (Polychaeta: Trichobranchidae) from the deep Southern Ocean, with a key to all described species, Zootaxa 3619, pp. 1-45 : 33

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.

Figures

FIGURE 25. Terebellides sp. C (ZMH- 26014), A—anterior thorax, dorsal, B—anterior thorax, ventral, C—shape of branchial lamellae, D—median abdominal uncinigers, MG-staining pattern, E—MG-staining pattern of anterior segments.

FIGURE 26. Terebellides sp. C (ZMH- 26014), MG-staining, A—anterior thorax, dorsal, B—abdomen, ventral, C—anterior thorax and posterior abdomen, D—anterior thorax, ventral, E—anterior thorax, lateral, F—anterior thorax, lateral.