Ammotrypanella arctica McIntosh 1879

Ammotrypanella arctica McIntosh, 1879

(Fig. 3 C–E)

Holotype. Davis Strait, Greenland (1785 fms), Globigerina-ooze, H.M.S. Valerous, Sta. 16, 55°10’N, 25°58’W, 1875 (NHM, 1921.5.1.2392).

Additional material. ANDEEP I–II, Scotia Sea northeast off Elephant Island, Sta. 42-2, 27 January 2002, 59°40.29’S, 57°35.43’W, 3683–3690 m, EBS, 2 specimens, Weddell Sea, Antarctic Peninsula, Sta. 131-3, 0 5 March 2002, 65°19.83’S, 51°31.62’W, 3049–3050 m, EBS, 7 specimens, Sta. 134-4, 0 9 March 2002, 65°19.20’S, 48°3.81’W, 4066–4069 m, EBS, 1 specimen.

Additional records. Hartman & Fauchald (1971) —A66, 38°46.7’N, 70°08.8’W, 2802 m; A70, 36°23’N, 67°58’W, 4680 m; A121, 35°50’N, 65°11’W, 4800m; A125, 37°24’– 37°26’N, 65°54’– 65°50’W, 4825 m; A122, 35°50’– 35°52’N, 64°57.5’– 64°58’W, 4833 m; A124, 37°26’– 37°25’N, 63°59.5– 63 °58’W, 4862 m; A120, 34°43’– 34°40.5’N, 66°32.8– 66 °35’W, 5018–5023 m; Ch 84, 36°24.4’N, 67°56’W, 4749 m; Ch 100, 33°56.8’N, 65°47’W, 4743–4892 m.

Diagnosis. The species can be recognized by the characters of the anal tube which are the lack of a ventral cirrus and the presence of numerous short cirri on the posterior margin.

Redescription. Holotype incomplete, body long and thin, 15 mm long and 1 mm wide for 42 chaetigers.

A moderately large species of 9–33 mm length and 0.5–2 mm width; number of chaetigers 37–43. With ventral groove along whole length of body. Posterior body region laterally flattened. Color in alcohol white to a light tan.

Prostomium conical with a short palpode. Peristomium a thin ring around the lips. Nuchal organs apparent as narrow lateral grooves, eyes absent (Fig. 3 C–D).

First following segment without chaetae. Anterior 8–10 parapodia button shaped with long, stiff chaetae in bushy fascicles. Following parapodia embedded in lateral groove. Posterior parapodia more distinct with long, straight chaetae. All chaetae simple.

Branchiae can be present in chaetigers 22–32, all branchiae of similar length, flat with wide base, tapering to top.

Posterior abranchiate chaetigers reduced in length, close to each other. Pygidium with anal tube; length of anal tube roughly equal to length of last 5–8 chaetigers; posterior margin with numerous short cirri, without ventral cirrus (Fig. 3 E).

Remarks. Ammotrypanella arctica is the type species of the genus. The holotype is of poor condition, the diagnostic characters, however, are still present. Therefore it is without doubt that the newly found specimens from the Southern Ocean belong to this species.

Distribution. North Atlantic to Atlantic sector of Southern Ocean and Antarctic Peninsula, 2014–5023 m