Smithsonian National Museum of Natural History

Original Description
 Hide the full description

“Orbiniella branchiata, new species

(Plate 33)

Record: 9:la sta. 740 (1, TYPE).

Description: An anterior end with 22 setigerous segments measures 4 mm long by 0.8 mm wide. The prostomium is broadly rounded (Fig. A), wider than long and lacks eyes or other surface marks. The next three segments are complete short rings; the first one forms the lower lip (Fig. B). Both dorsum and ventrum are smooth and broadly exposed except where the dorsal branchiae emerge from dorsolateral position. Separation between thorax and abdomen is gradual, from setiger 14. Branchiae are first present from the fourth setiger (Fig. C) where they are large, thick at the base and tapering in the distal half; they extend distally as far as the dorsal cirri and continue large on more posterior segments. Notopodia are papillar, with a slender, cirriform dorsal cirrus and 12 to 15 slender, camerated, capillary setae; the corresponding neuropodia have a ventral cirrus resembling the dorsal one, and 24 or more long, slender setae, some of which are broken off.

Abdominal parapodia have long notopodial and neuropodial cirriform lobes. Notosetae occur in slender fascicles and consist of camerated capil­lary setae, accompanied by one or several furcate spines in which the two branches are unequal. Neuropodia have similar though shorter slender capillary setae and one or two thicker, shorter, distally slightly curved, acicular spines resembling those in species of Scoloplos (Leodamas).

Orbiniella branchiata differs from typical species of the genus in hav­ing three asetigerous anterior segments; abdominal neuropodia have curved acicular spines accompanying the camerated capillary setae. The prostomium is anteriorly broadly rounded, not triangular as in species of Scoloplos (Leodamas). The species is referred to Orbiniella chiefly be­cause it has more than one anterior, asetigerous segment.

Distribution: Drake Passage, in 384-494 m.”

(Hartman, 1967)