Comprehensive Description

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Description

Pholoe antipoda, new species

 

(Plate 7, Figs. B, C)

 

 

Records: 3:6b sta. 969 (2); 6:11 sta. 558 (fgm); 9: la sta. 740 (10, TYPE); 11:3 sta. 993 (6).

 

Description: Length of a larger specimen is 3.1 mm, width 1 mm and setigerous segments number 24. The body is small, depressed, trun­cate at both ends, and smooth on dorsum and ventrum. Elytra are broadly imbricated, completely cover the dorsum and may number 12 or 13 pairs; they are inserted as typical of the genus. The prostomium, covered by the first pair of elytra, is small, somewhat compressed be­tween the first pair of segments ; it has four subequally large, dark eyes in trapezoidal arrangement with the posterior pair the wider apart ; the median antenna has a large, thick base ; a nuchal papilla is lacking. The proboscis, everted in one individual, has four horny, brown jaws and a surrounding sheath which terminates in six dorsal and six ventral well spaced, short papillae; they are separated laterally by a hiatus.

 

Elytra are nearly or quite smooth, except for sparse, inconspicuous papillae at lateral margins or along the exposed parts; the first are rhomboid in shape, and later ones are broader and excavate at the an­terior margin. Fig. B shows the approximate position of the scar and the entire margins of an anterior elytrum; most have a minutely crenu­lated margin along the posterior edge.

 

The first parapodium is reduced to a pair of cirri of which the dorsal one resembles the median prostomial antenna and the ventral one is much smaller ; setae are absent. Other parapodia are biramous ; notopodia are smaller and shorter than neuropodia. Notosetae are in close fascicles, consist of 20 to 30 very slender capillary setae, and are supported by a rodlike, yellow aciculum which is only about half as thick as the cor­responding neuro-aciculum. Neuropodia are larger, longer, directed lat­erally, and have series of composite falcigers of one kind, with the su­periormost slightly the longest, and the inferiormost the shortest but no significant difference between them. The shaft is distally oblique and has a row of denticles along the longest edge ; the appendage is distally fal­cate and the cutting edge has a row of minute denticles ( Fig. C).

 

Pholoe antipoda differs from other species of the genus in its much smaller size, reduced number of segments, and the details of elytra and parapodial falcigers.

 

This is the first record of the genus from Antarctic seas.

 

 

Distribution: Tierra del Fuego, in 229-265 m; Falkland Islands, in 646-845 m; Drake Passage, in 384-494 m; and South Shetland Is­lands, in 300 m.”

 

(Hartman, 1967)

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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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