Body small, thin, arched dorsally, flattened ventrally.
Prostomium rounded, about as long as broad; without eyes. Two palps ventrolaterally, reaching chaetiger 3. Palps divided into a long base and a short distal part. Two antennae, anterior to the palps, reach chaetiger 6 or 7, with 20-25 annulations.
The first 2 segments without chaetae, parapodia or appendages, but each surrounded by a ring of cilia. Other segments have well-developed parapodia and from chaetiger 12-16 onwards they have 2 ciliary bands each.
Parapodia with short postchaetal lobes. Dorsal cirri on long cirrophores with aciculae, absent on the first chaetiger. Ventral cirri are long and finger-shaped. 1-3 simple bidentate and 0-2 forked chaetae above the acicula and 6-10 compound chaetae beneath it.
Pygidium with two long and one short cirrus.
Proboscis long; mandibles smooth, X-shaped. Maxillae: upper row with bidentate plates, Basal plate with 16-22 teeth and lower row similar to upper row. Maxillary carrier with 10-13 teeth (O. subaequalis-jaw plates).
Incomplete specimen 11 mm for 63 segments.
Living animal whitish.
In mud, to about 30 m depth.