Prostomium with two large, quite mobile palps (up to 520 µm long); arising lateroventrally. No antennae. Two eyes, greatly varying in size and not present in all specimens. Two nuchal organs, arising from each side of the mouth and extending to the dorsal surface. Nine chaetigerous segments. Parapodia each with an ovoid cirrus and 2 bundles of chaetae, except for those of segment 1, which each have only a dorsal bundle of short chaetae. Cirri differing greatly in size and shape, posterior ones conspicuously larger than anterior ones. Cirri of segment 1 extremely small. Mature males and, especially, mature females with cirri of posterior 3 segments egg-like, enlarged and inflated, with a small apical knob and packed with refractile granules. Chaetae simple capillaries without serrations; up to 23 in one parapodium. External ciliation similar to that of Nerilla antennata , midventral ciliated band, broadening in pharyngeal region; between each segment a band of cilia that in some individuals forms a complete ring dorsally; short oblique ciliary bands near the insertion of the ventral chaetae; a lateral tuft of cilia halfway between successive parapodia. Pygidium with two spindle-shaped, distally tapering cirri (length 120 µm and more). Buccal pieces unknown.
Length 1.5 to 2.1 mm.
Opaque; no pigmentation.
Intertidal sand at midtide level. Coarse shell-gravel in subtidal area down to 22 m depth.
North Sea (South-East coast of Scotland, near Dunbar), Skagerrak (West coast of Sweden, near Gullmarfjord).