Kingston & Mackie, 1980
Body long, foremost thoracic segments clearly wider than the rest of the body. Tentacular ridge semicircular with numerous tentacles of two types: moderately long, grooved spatulate ones and short club-shaped ones. Behind the tentacles on either side of the dorsum 6-8 brown eyespots. Upper lip simple, fleshy and protruding. Lower lip less conspicuous. Buccal segment projecting ventrally in a forked process. Segment 2 ventrally reduced, with a pair of small rounded ventrolateral lobes. Segments 3 and 4 with well-developed lateral lobes fused to ventral projections forming collars. Lateral lobes of segment 3 with ciliary ridges on both inner and outer surfaces, those of segment 4 on inner surface only. Segment 5 with narrow lateral lobes. Segment 2 with a pair of thick filamentous gills, segment 3 with a pair of broad, leaf-like gills terminating in a short narrow, leaf-like gills with a short filamentous process. The last three pairs of gills have relatively flat, ciliated upper surfaces, and each two lower, ridged surfaces forming the sides of an acute wedge. Posterior gills nearer to the middorsum than the anterior ones; bases of gills arranged in a semicircle opening forwards (O. floriceps-gills ). Notopodial chaetae smooth, starting at segment 4. Sixteen thoracic chaetigers. Uncinigerous tori from segment 7. Thoracic uncini with long shafts, abdominal uncini with short shafts (O. floriceps-uncini). Pygidium lobate with a pair of ventrolateral cirri (O. floriceps-posterior end).
Up to 36 mm for 83 segments.
In formaldehyde colourless with light bands marking the ciliary ridges on the gills and lateral lobes.
On very fine sand or silt; 145 to 370 m.
Northern North Sea, Norwegian trough, Norwegian west coast.