Huth, 1934
Description:
Body small and thin.
Prostomium rounded, without eyes. A pair of finger-shaped antennae and a pair of minute palps. Peristomium and apodous segment have a small intersegmental ring between them. Prostomium, peristomium and each segment with a complete ring of cilia.
Parapodium with oval lobe and one acicula. Dorsal and ventral cirri absent. Chaetae of four kinds: 1) 1-2 simple finely toothed pointed chaetae; 2) 1-2 simple, sub-distally flattened, smooth hooks; 3) 2-4 compound chaetae with long or short smooth hooked blades; 4) 1-2 simple smooth hooks (O. gracilis-parapodium).
A pair of short finger-shaped pygidial cirri.
Mandibles X-shaped, with anterior margins toothed, subequally V-shaped. Maxillary carriers fused to each other and to hooked basal maxillae; basal maxillae each with 7-8 teeth along the cutting edge and serrations between the teeth. Seven pairs of toothed plates (maxillae) (O. gracilis-jaw plates).
Size:
Up to 4 mm for 27 chaetigers.
Colour:
White.
Habitat:
Interstitially in sand, gravel, and fragments of shells and of Corallina , from intertidal zone to shallow subtidal depths.
Distribution:
North Sea and English Channel (Roscoff).