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 : 29-30

Terebellides sp. A

Figs 21, 22

Material examined: ANDEEP II, St. 133-5, GKG 54 (ZMH-26010)

Description:

Single specimen 7 mm in length, 1.6 mm in width, posteriorly incomplete with 18 thoracic chaetigers.

Head region: Tentacular membrane largely expanded and folded. Lower lip rectangular, distinctly expanded. Tentacles only numerous short simple ones on the outer margins of tentacular membrane present ( Fig. 21).

Branchiae: Branchial lobes free from each other, lamellae broad, loose, with filamentous tips. Posterior branchial lobes smaller than anterior ones ( Fig. 22 A). Fifth branchial lobe absent. Annulation of branchial stem not determinable, possibly present.

Anterior chaetigers: First chaetiger’s notopodia somewhat reduced in size with chaetae more or less originating from body wall ( Figs 21, 22 A, B). Geniculate hooks present on TC-6 (segment 8) only. About 5 per side, strongly protruding, sharply bent ( Fig. 22 C).

Lateral lappets: Present from TC-1–7, with TC-1=3>2>4=5=6>7 ( Fig. 21).

Ventral pads: Entire ventrum glandular, individual segments well differentiated with elevated anterior margins to each segment, segments 3 and 4 larger than subsequent ones.

Nephridial papillae: Segments 3, 6, 7.

MG staining pattern 5 ( Figs 2 , 22 ): With “glandular” white field in TC-3 (segment 5), anterior segments solid, striped from about TC-8. Notopodia stain, while neuropodia do not. White bands absent, anterior margins of TC-3 and TC-4 somewhat darker than those of other segments.

Pygidium: Unknown.

Remarks: This species is characterised by having a compact and broad thorax, and resembles shallow water species examined by both authors. However, if differs from other described species in the region by having stout branchiae and the observed methyl green staining pattern 5..

Habitat: Western Weddell Sea upper continental slope in 1166 m. Known only from a single specimen.

Figures

FIGURE 2. MG staining patterns of observed species, adapted and extended from Schüller & Hutchings (2010).

FIGURE 22. Terebellides sp. A (ZMH- 26010), MG-staining, A—anterior thorax, lateral, B—anterior thorax, ventro-lateral, C—geniculate hooks on TC- 6.