Anobothrus pseudoampharete, 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 : 54

Anobothrus pseudoampharete sp. nov.

(Fig. 2A–H)

Holotype. ANDEEP III, eastern Weddell Sea, st. 74-6, 20 February 2005, 71°18.42’ S, 13°58.21’ W, 1047 m, EBS, ZMH P- 24741.

Paratypes. ANDEEP III, eastern Weddell Sea, st. 74-6, 20 February 2005, 71°18.42’ S, 13°58.21’ W, 1047 m, EBS; 50 specimens, ZMH P- 24742.

Additional material. 42-2 (1), 133-3 (1), 143-1 (7), 21-7 (1), 74-6 (53), 81-8 (3), 121-11 (9), 133-2 (4), 142-5 (1), 150-6 (12), 154-9 (1).

Etymology. The name refers to the strong reminiscence of this species to Ampharete kerguelensis McIntosh, 1885 at first sight.

Diagnosis. The species can be recognized by the paleae which are wide at the base and then abruptly taper to a long, delicate tip.

Description. Holotype complete except for lack of branchiae, 5 mm long and 0.5 mm wide for 30 chaetigers.

A species of median size, between 3–13 mm long. Body long, gradually tapering to the posterior end (Fig. 2A). Color in alcohol light tan to white.

Prostomium slightly scoop-shaped, fused to peristomium and anterior segments. 15 thoracic chaetigers present, first bearing pairwise whirls of 15–20 paleae. Paleae stout and broad at base suddenly tapering to a delicate tip (Fig. 2B). First two subsequent segments only with notopodia. Twelve thoracic uncinigers and up to 15 abdominal uncinigers. Fifth-to-last thoracic unciniger with elevated parapodia connected by a dorsal ridge, with modified chaetae and uncinigers (Fig. 2E, G).

Thoracic chaetae limbate, of two sizes (Fig. 2D). Limbate chaetae of fifth to last chaetiger of three sizes plus some simple capillaries (Fig. 2E). Thoracic uncini with three rows of small teeth, laterally kidney shaped (Fig. 2F). Those of fifth-to-last chaetiger also with three rows of teeth, more or less round in lateral view (Fig. 2G). Abdominal uncinigers lacking notopodia, neuropodia with uncini with four rows of small teeth, one row of three teeth and one median main tooth (Fig. 2H).

Pygidium with uneven margin, cirri lacking, anus terminal (Fig. 2A).

Eight pairs of branchiae present, arranged in a row. Branchiae rather robust, digitiform (Fig. 2C), reaching back to about third chaetiger.

Remarks. Only two further species of the genus Anobothrus Levinsen, 1884 are known from the Southern Ocean to date. The species most similar, A. gracilis ( Malmgren, 1866) , bears very long paleae that gradually taper in width from base to tip. The paleae of A. pseudoampharete sp. nov. in contrast are shorter and very wide in their complete basal half. They taper suddenly to a fine, long tip in their distal half.

Distribution. Atlantic sector of Southern Ocean and Antarctic Peninsula, 774–4574 m