O. Schmidt, 1857
Description:
Female:
Anterior part of prostomium with four bristle-like groups of stiff adjoined cilia and two thick-set transverse rings of cilia; anterior ring dorsally complete, running across the eyes and continuing backwards in a gentle curve, becoming broadly V-shaped on mid-dorsal ridge; posterior ring incomplete dorsally. Following rings of trunk incomplete or complete: segment 1 with two incomplete rings; segments 2 to 4 with complete rings; segment 5 with an incomplete ring. Scattered cilia on both sides of the anal region. Prostomial rings and first trunk ring run into an extended field of cilia on ventral side of prostomium and around mouth; other rings join the mid-ventral band of comparatively short cilia. A pair of ciliated pits laterally situated in a groove between the prostomium and the trunk.
Male:
Body without segmentation; pear-shaped if seen from above. With three ciliary fields: an anterior ventral, a smaller posterior ventral and a very small dorsal. Several single sensory cilia. Eversible penial cone with stylet-like structures.
Size:
Female up to 1.3 mm for 5 segments, if the two rings of the buccal region are considered to be on segment 1.
Male up to 50 µm.
Colour:
Female whitish; male transparent.
Habitat:
Various intertidal substrata, especially in sheltered pools. Most records originate from marine aquaria, where the species lives in the layer of debris on the bottom of the tanks.
Distribution:
North Sea (Helgoland, Sylt, English east coast), English Channel, European and American Atlantic coasts, Mediterranean.