(Lastochkin, 1935a)
Description
Small transparent worms. Prostomium not broader than subsequent segments, divided into three "segments" with transversal furrows; its ventral side ciliated. No sensory pits. Body cylindrical, with distinct external segmentation, ending in small tail-like appendage. Numerous colourless, unicellular adhesive glands in body wall. Both dorsal and ventral chaetal bundles in II-VII, located laterally, consisting of two (seldom 3-4) hair chaetae of different lengths, finely serrated in their distal third. In mature individuals, two pairs of testes in IV and V, one pair of ovaries in V, small unpaired, ventral male pore on anterior edge of VI, and similarly unpaired ventral female pore, surrounded with crown of clitellum-like gland cells, in 6/7; unpaired spermatheca opening immediately before female pore. Length 1-1.3 mm, width up to 0.11 mm, segment number 7. The only known species in the family differing from the Aeolosomatidae in constant segment number, constant number and position of testes and ovaries, as well as in presence of well-developed genital ducts.
Crawling on substratum in interstitial crevices.
Distribution
Europe.
Ecology
In freshwater, particularly in sand bottom of large rivers.
Reproduction
Sexual. Cocoons with single eggs attached to substratum and covered with foreign particles.
Literature
Lastochkin, 1935a: 636-643; Lastochkin, 1935b: 488; Lastockin, 1937: 233; Bunke, 1967: 335-360, Figs 76-97; Van der Land, 1971: 692-693, Fig. 13.3.E; Jouin, 1973: Fig. 1C-E; Kasprzak, 1981: 87-89, Figs 158-164.