Ophelina robusta, Schüller, Myriam, 2008

Schüller, Myriam, 2008, New polychaete species collected during the expeditions ANDEEP I, II, and III to the deep Atlantic sector of the Southern Ocean in the austral summers 2002 and 2005 — Ampharetidae, Opheliidae, and Scalibregmatidae, Zootaxa 1705, pp. 51-68 : 60-62

Ophelina robusta sp. nov.

( Fig. 4 C–D)

Holotype. ANDEEP I – II; Weddell Sea, Antarctic Peninsula, Sta. 131-3, 0 5 March 2002, 65°19.83’S, 51°31.62’W, 3049–3050 m, EBS, ZMH P- 24759.

Paratype. ANDEEP III, Weddell Sea, Sta. 121-11, 14 March 2005, 63°38.27'S, 50°37.16'W, 2668 m, EBS, 4 specimens, ZMH P- 24760.

Additional material. 78-9 (10), 80-9 (2), 150-6 (5), 151-7 (2), 153-7 (7).

Etymology. The name refers to the presence of a very robust ventral cirrus on the anal tube.

Diagnosis. A diagnostic character of this species is the presence of median sized branchiae in the first 7– 8 parapodia. Enlarged branchiae are present in the posterior region of the body. The anal tube bears a robust ventral cirrus.

Description. Holotype complete, 18 mm long and 1.5 mm wide for 30 chaetigers.

A species of median size. Length about 18–23 mm, width 1–2 mm, number of chaetigers between 30–35. Color in alcohol a light tan.

Prostomium conical, carrying a distinct palpode. Peristomium limited to the lips. Nuchal organs present, but indistinct. Eyes absent ( Fig. 4 C).

First follwing segment achaetous. Subsequent segments with reduced button-shaped parapodia. Anterior chaetigers with slight annulation. Segmental sutures indistinct in median body region becoming more apparent in posterior body region.

Chaetae simple capillaries throughout, anterior ones long and curved, median ones short, and posterior ones longer but few.

Anterior 7–8 branchiae distinct, of median length. Very small and indistinct branchiae in median body region becoming long and flat in posterior part of body.

Posterior chaetigers laterally flattened, terminally with an anal tube. Anal tube pseudoarticulated, bearing a robust ventral cirrus ( Fig. 4 D).

Remarks. The species is similar to Ophelina setigera and O. ammotrypanella sharing the presence of prolonged chaetae in anterior segments. It differs from both species by bearing a robust ventral cirrus on the anal tube. The anterior branchiae are larger than that of O. ammotrypanella , but still shorter than the posterior branchiae of both species.

Distribution. Atlantic sector of Southern Ocean and Antarctic Peninsula, 1178–3138 m

Figures

FIGURE 4. A – B Ammotrypanella mcintoshi sp. nov. A. anterior segments, B. posterior segments; C – D. Ophelina robusta sp. nov. C. anterior segments, D. posterior segments; E – F. Ophelina ammotrypanella sp. nov. E. anterior segments, F. posterior segments.