Oligobregma quadrispinosa, 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 : 40-41

Oligobregma quadrispinosa sp. nov.

( Fig. 3 A–4B)

Holotype. Scotia Sea, South Sandwich Islands, east off Montagu Island, Sta. 141­10, 23 March 2002, 58°25.08’S, 25°0.77’W, 2258–2313 m, EBS ( ZMH, P­ 24736)

Paratypes. Weddell Sea, Sta. 131­3, 0 5 March 2002, 65°19.83’S, 51°31.62’W, 3049–3050 m, EBS, 8 specimens ( ZMH, P­ 24738); Sta. 134­4, 0 9 March 2002, 65°19.20’S, 48°3.81’W, 4066–4069 m, EBS, 2 specimens ( ZMH, P­ 24737), Scotia Sea, northwest off Elephant Island, Sta. 42­2, 27 January 2002, 59°40.29’S, 57°35.43’W, 3683–3690 m, EBS, 5 specimens (NHM 2006.1699­1703).

Etymology. The name refers to the presence of acicular spines in the first to fourth notopodia.

Diagnosis. The species can be distinguished by the size of the posterior parapodial cirri and the presence of acicular spines in the first to fourth notopodia.

Description

Holotype complete, 11 mm long and 2 mm wide for 28 chaetigers.

A moderately large species, 8–11 mm long and 1.5–2 mm wide for 28 chaetigers. Colour in alcohol: white to a light tan; body anteriorly expanded from chaetigers 5–13 ( Fig. 3 A).

Prostomium anteriorly with 2 rounded lobes; no eyes; nuchal organs not apparent; peristomium well developed, partially covering prostomium, appearing as up to 3 rings; proboscis saclike, without papillae ( Fig. 3 B).

Anterior and middle chaetigers quadriannulated, posterior ones with 5 annulations; anterior parapodial lobes reduced, increasing in size towards median and posterior region; dorsal cirri of posterior parapodia enlarged, ventral cirri almost foliose ( Fig. 4 A–B).

Chaetigers 1 and 2 with heavy acicular spines in notopodia, arranged in 2 rows; 1 row of acicular spines in notopodia of chaetigers 3 and 4 ( Fig. 3 B); spines smooth and sickle­shaped ( Fig. 3 C); capillary chaetae in all rami, accompanied by furcate chaetae from chaetiger 5; furcate chaetae covered by fine hairs; tynes unequal in length, short tyne about ¾ of long one ( Fig. 3 D).

Pygidium terminal, ringlike; slightly pointed, bearing at least 2 long and slender anal cirri ( Fig. 3 A). Remarks. The great size of the posterior dorsal and ventral cirri of O. quadrispinosa sp. nov., clearly distinguishes it from other species of Oligobregma . The shape of the prostomium and its concealment under the peristomium are similar to O. notiale Blake, 1981 . The arrangement of acicular spines in the anterior notopodia, however, indicates a close relationship to O. collare . Oligobregma collare has two rows of acicular spines in the first two chaetigers and one row in the third. Oligobregma quadrispinosa sp. nov., bears an additional row in chaetiger four.

Distribution. Scotia and Weddell Seas, in 2258–4069 m.

Figures

FIGURE 3. A­D. Oligobregma quadrispinosa sp. nov. A. entire animal, dorsal view; B. anterior segments with everted proboscis, dorsal view; C. acicular spine; D. furcate chaeta.

FIGURE 4. A­B. Oligobregma quadrispinosa sp. nov. A. median parapodium; B. posterior parapodium.