Bretscher, 1896
Description
Small and stout, transparent worm, usually occurring as a chain of several zooids. Five anterior segments fused forming head and containing muscular pharynx. Prostomium absent. Chaetae in ventral bundles only, absent from III-V. In II, chaetae 3-9 per bundle, 63-100 µm long, with upper tooth longer. From VI on, chaetae 3-6 per bundle, 35-68 µm long. In mature individuals, penial chaetae by 2. Length 0.8-2 mm, segment number in zooids 8-9, in single individuals 8-21. Can be confused with very young individuals of Chaetogaster diaphanus. Differing from another common small species, Chaetogaster diastrophus, by lack of prostomium. In the closely related, probably synonymous species Chaetogaster parvus Pointner, 1914 chaetal teeth are equal and "head" segments thinner than subsequent ones; rudiment of prostomium is known to bear short sensory hairs visible only in living animals. Known from Western and Central Europe.
Crawling on substratum.
Distribution
Almost cosmopolitan.
Ecology
In various freshwater bodies, seldom in slightly brackish water, living on water plants and bottom sediment. Feeding on minute animals and algae.
Reproduction
Paratomy (budding). Sexually mature individuals rare.
Literature
Bretscher, 1896: 512-513, Fig. 1; Sperber, 1948: 63-65, Figs 7C,H, Pl. I Fig. 2; Sperber, 1950: 52, Fig. 3C; Brinkhurst and Jamieson, 1971: 309-310, Fig. 7.1F-H; Chekanovskaya, 1981: 260-262, Fig. 122; Hrabe, 1981: 33-34; Kasprzak, 1981: 94-95, Figs 186-190. For Chaetogaster parvus: Pointner, 1914: 606-607, Pl. XVIII Fig. 1; Sperber, 1948: 65-66; Lafont, 1981a: 211-217, Figs 1-2.