Kallstenius, 1892
Description
Very small transparent worms. No eyes. Segment III prolonged. Stomach in V-VI. All chaetae similar, bifid, fine, with equal teeth. Dorsal chaetae beginning from III. Dorsal chaetae of III and ventral chaetae of II usually 4 per bundle, the rest of chaetae usually 3 per bundle; 42-52 µm long. No penial chaetae, but clitellum in mature worms in 1/2 V-VI. Length of the first zooid 1.5 mm, segment number 9.
Crawling on substratum.
Distribution
Palaearctic.
Ecology
Mostly in brackish but sometimes also in freshwater, mostly on sand. Feeding mostly on unicellular algae.
Reproduction
Mostly asexual, by paratomy (budding). Mature individuals and sexual reproduction rare or seasonal.
Literature
Kallstenius, 1892: 42-55, Figs 1-5; Sperber, 1948: 76-81, Figs 7L,M, Pl. II Figs 4, 5; Sperber, 1950: 55, Fig. 4-5; Brinkhurst and Jamieson, 1971: 316, Fig. 7.2A-B; Chekanovskaya, 1981: 253-254, Fig. 116; Kasprzak, 1981: 92, Figs 167-168.