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Description

"Ammotrypane setigera n. sp.
Figs. 30a, 30b

 

Material. Weddell Sea, in 1664-4757 m: Station 68-18 (1 specimen); 68-55 (1 specimen); 69-19 (1 specimen); 69-21 (39 specimens); 69-22 (holotype and 7 paratypes, USNM 46894-5); 69-23 (16 speci­mens); 69-26 (2 specimens); 69-27 (2 specimens).

 

Description. The holotype (USNM 46894) is 29 mm long and 2 mm wide for 37 setigers. Other speci­mens, from station 69-21 (USNM 46899), are 17-40 mm long and 1.5-3.3 mm wide and consist of 32-43 setigers. Smaller individuals have fewer setigers, ranging from 30 to 33; in other respects they resem­ble the larger ones.

 

The prostomium has a slender anterior palpode (Figure 30a) and is long and oval or broadly tra­pezoidal; the shape varies according to the position of the nuchal organs and the proboscis. When the prostomium is withdrawn, it is oval; when it is everted, it is trapezoidal (Figure 30a). The achaetous peristomium is a long smooth ring, inter­mediate in width between the prostomium and first setigerous segment. The parapodia of the first setiger are postoral and smaller than those of subse­quent setigers.

 

Setigers 1-7 are broadest and quadriannulate and have the second, or largest, annulus bearing the lateral parapodia, with numerous long setae in biramous fascicles directed laterally. Setigers 9-17 to 19 are narrower and longer; the last 16 setigers are short and crowded. All parapodia have long fleshy postsetal lobes and similar but shorter presetal ones (Figures 30a, 30b). Setae are of one kind, long, slender, capillary, and marginally smooth.

 

A specimen from station 69-21 (USNM 46899) has the proboscis everted; it is long, smooth, and

 

Pouchlike and has a midventral longitudinal furrow. Branchiae are long a cirriform and present from setiger 2 to at least setiger 25; thereafter, they are irregular or absent. The last 16 setigers and their parapodia diminish gradually posteriorly (Figure 30b). The anal funnel is compressed, cylindrical, and longest middorsally; the distal margin is encircled by 12-14 short digitate processes (Figure 30b)

 

Remarks. Ammotrypane setigera is distinguished from other species of Ammotrypane by having the first seven setigers with the most conspicuous setal fascicles."

 

(Hartman, 1978)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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