Comprehensive Description

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Description

"Aglaophamus ornatus, new species

 

(Plate 24)

 

 

Aglaophamus virginis Hartman, 1953, p. 30 (in part).

 

Aglaophamus macroura Hartman, 1964, p. 103 (in part).

 

 

Records: 1

 

0: 6 sta. 678 (1); 10:11 sta. 734 (2) ;

 

12: 5 sta. 1003 (2, TYPE); 12: 8 sta. 437 (1); 12:13 sta. 420 (1);

 

12:16 sta. 997 (1); 12:17 sta. 432 (4); 12:19 sta. 428 (2);

 

15: 1 sta. 612 (2); 15: 3 sta. 1054 (1); 16: 8 sta. 52-63 (9);

 

16: 9 sta. 7-63 (4); 16:12 sta. 49-63 (3); 16:13 sta. 74-63 (1);

 

16:14 sta. 67-63 (5); 16:16 sta. 32-63 (3); 16:20 sta. 62-63 (1);

 

16:21 sta. 66-63 (1); 16:22 sta. 45-63 (1); 16:23 sta. 48-63 (1);

 

16:27 sta. 28-63 (1); 16:28 sta. 64-63 (1); 16:29 sta. 439 (fgm).

 

 

Description: Large individuals measure 80 to 200 mm long by 5.2 to 7 mm wide and consist of up to 190 segments. Individuals from the Ant­arctic Peninsula and Bransfield Strait are dark purple to nearly black; others are pale with a purplish brown midventral stripe. The prosto­mium is subrectangular, wider than long, and has two pairs of antennae; the anterior, smaller ones are at the frontal ectal margin, and the pos­terior larger pair is inserted far back and ventrolaterally. There are no visible eyes. The oral field extends back through the ventrum of the seventh segment. The muscular proboscis terminates in a circlet of bifid papillae; subterminal rows number 13 or 14, and each of these rows is replaced by a triangular patch, each of the multiple rows with 8 to 10 much smaller papillae in longitudinal rows. The proximal surface of the proboscis is smooth.

 

Interramal cirri are involute, first present from the second segment and at first very small and inconspicuous; they increase in size rapidly so as to inscribe a coil within a few segments; they are continued posteriorly to near the end of the body; only the last five or six segments lack them. Parapodia are well developed throughout. Anteriormost noto­podia and neuropodia have deeply incised, well separated acicular lobes (Fig. A). A broad foliaceous superior lobe extends like a saddle over the notopodial base, and a slender, triangular notopodial lobe makes con­tact with the base of the interramal cirrus. Setae occur in full, spreading fascicles. Farther back the acicular lobe is only slightly incised to rounded; the superior lobe enlarges, and the notopodial cirrus is foliace­ous, broadly cordate to somewhat rhomboid (Fig. B); it replaces or ob­scures the much shorter postsetal lobe. Neuropodia, at best development, have an erect lobe which is digitate in median segments; the ventral edge is conspicuously crenulated, and shows considerable variation along the length of the body and among individuals within a lot. The neuropodial postsetal lobe is greatly prolonged, broad and extends distally beyond most of the long setae. The preacicular lobe is shortest, located in front of the rounded acicular lobe.

 

A small papillar process, between the preacicular and acicular lobes in neuropodia, is characteristic but easily overlooked. Acicula are yel­low, distally recurved, and project from the ends of the acicular lobes or lie buried in them; they may be somewhat retracted into the parapodial tissue. Preacicular setae are transversely barred; postacicular setae are slender and smooth along the cutting edge or lightly serrated. Posterior-most parapodia have greatly reduced parapodial lobes (Fig. C); the noto­podial lobe is much constricted and the acicular lobes are most promi­nent.

 

A. ornatus differs from other species in the early origin of the in­terramal cirrus, first present though small at segment two and continued to near the end of the body. Notopodial lobes are unusually large and approach the superior lobe in size. Anterior acicular lobes are deeply in­cised and rounded in median segments. Postsetal lobes of neuropodia have a crenulated ventral edge in postmedian segments.

 

Small coiled nematodes are occasionally seen attached to the anterior side of notopodia, usually one on a parapodium. Some individuals have colonies of endoproct bryozoans, possibly Loxosomella, along the outer edges of interramal cirri.

 

Aglaophamus virginis Hartman (1953, p. 30), from the Falkland Is­lands in 75 m (not Kinberg, 1866), is here referred to A. ornatus. A. virginis Kinberg is described below.

 

 

Distribution: Scotia Sea, in 732-1400 m; Bransfield Strait, in 210­1120 m; South Sandwich Islands, in 101-1080 m; Antarctic Peninsula, in 25-165 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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