Oligobregma pseudocollare, Schüller, Myriam & Hilbig, Brigitte, 2007

Schüller, Myriam & Hilbig, Brigitte, 2007, Three new species of the genus Oligobregma (Polychaeta, Scalibregmatidae) from the Scotia and Weddell Seas (Antarctica), Zootaxa 1391, pp. 35-45 : 38-40

Oligobregma pseudocollare sp. nov.

( Fig. 2 A–E)

Holotype. Scotia Sea northeast off Elephant Island, Sta. 46­7, 30 January 2002, 60°38.35’S, 53°57.36’W, 2889–2892 m, EBS ( ZMH, P­ 24733)

Paratypes. Scotia Sea northeast off Elephant Island, Sta. 46­7, 30 January 2002, 60°38.35’S, 53°57.36’W, 2889–2892 m, EBS, 19 specimens ( ZMH, P­ 24734); Scotia Sea, South Sandwich Islands, east off Montagu Island, Sta. 143­1, 25 March 2002, 58°44.69’S, 25°10.27’W, 753–774 m, EBS, 8 specimens (NHM 2006.1691–1698); Weddell Sea, Antarctic Peninsula, Sta. 131­3, 0 5 March 2002, 65°19.83’S, 51°31.62’W, 3049–3050 m, EBS, 1 specimen ( ZMH, P­ 24735).

Etymology. The name refers to the strong resemblance of the species to Oligobregma collare ( Levenstein, 1975) .

Diagnosis. This species can be distinguished by the presence of two rows of acicular spines in the first and second notopodia.

Description

Holotype incomplete, posterior segments in poor condition, pygidium missing; 6.5 mm long and 1.3 mm Prostomium with 2 rounded lobes projecting from anterolateral margin; no eyes; nuchal organs not apparent. Peristomium well developed, forming 1–2 achaetous rings lateral to prostomium; proboscis smooth and saclike ( Fig. 2 B).

Chaetigers 1–3 smooth, following segments becoming rugose; anterior chaetigers tri­ to quadriannulated, 5 annulations present from chaetiger 10 ( Fig. 2 A). Anterior parapodia reduced to simple lobes; medial and posterior parapodial lobes becoming more distinct, conical, with short conical dorsal and ventral cirri ( Fig. 2 C); interramal sense organs apparent between posterior noto­ and neuropodia.

Chaetigers 1 and 2 with strong, sickle­shaped acicular spines in notopodia in addition to capillaries; spines arranged in 2 rows, surface smooth ( Fig. 2 A, D); all noto­ and neuropodia with capillaries; short furcate chaetae present in both rami from chaetiger 3, covered by fine hairs; tynes unequal in length, short tyne about half of long one ( Fig. 2 E).

Pygidium terminal; unknown for adult types; juvenile pygidium trilobate, without cirri.

Remarks. Oligobregma pseudocollare sp. nov. is most closely related to O. collare also known from deep Southern Ocean. The two species resemble each other in the shape of the pro­ and peristomium and the texture of the body surface. Oligobregma pseudocollare sp. nov., however, is more strongly annulated with four to five annulations. Oligobregma collare only bears three to four. The two species can easily be distinguished by the number of the anterior notopodia armed with acicular spines. Oligobregma pseudocollare sp. nov., has acicular spines in chaetigers one and two, arranged in two rows while O. collare shows an additional row of spines in chaetiger three.

Distribution. Scotia and Weddell Seas, in 753–3050 m.

Figures

FIGURE 2. A­E. Oligobregma pseudocollare sp. nov. A. anterior and median part; B. everted proboscis; C. posterior parapodium; D. acicular spine; E. furcate chaeta.