Harmer, 1889
Description:
Prostomium with two ciliary rings, each with a mid-dorsal interruption. Second ring especially wide, encircling the prostomium at its greatest diameter. Anterior part of the prostomium with four large and several small bristle-like groups of stiff adjoined sensory cilia; with additional single cilia. Ventral side of trunk completely covered with a dense mat of cilia from which two transverse rings per segment run to dorsum. Trunk rings 1-9 dorsally uninterrupted, consisting of individual tufts, which may be distinctly separated from each other. Rings 10 and 11 only in form of lateral transverse rows; small tufts at the level of the anus may belong to a reduced 12th ring. An indistinctly bordered ciliated pit laterally on each side between prostomium and trunk. Two eyes. Caudal appendage, ventral, prominent, extending beyond anus as a bluntly pointed lobe with ventral ciliation and numerous sensory cilia.
Males and females similar: Females with two pairs of ovaries. Mucous cocoon with up to 16 eggs. Males with one pair of testes which may fuse across the mid-line and then occupy most of the body cavity; one pair of ovoid vesiculae; unpaired copulatory organ.
Size:
Up to 2.5 mm for 5 segments, if the two rings of the buccal region are considered to be on segment 1.
Colour:
Reddish orange.
Habitat:
Sheltered tide pools rich in diatoms, Enteromorpha spp. and Ulva lactuca.
Distribution:
North Sea, English Channel, Irish Sea, Atlantic, Spanish coast, Baltic (Bay of Kiel), Skagerrak, White sea, Barents Sea.