Amphichaeta leydigi

Tauber, 1879

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, 5 per bundle; those of IV and V, 2 per bundle, and beginning from VI, 1-4 per bundle. Ventral bundles of II and III with 4 chaetae, of IV and V with 2 chaetae, and in the rear segments with 1-4 chaetae, all 40-85 µm long. No penial chaetae, but clitellum in mature worms in 1/2 V-VI. Length up to 4 mm, segment number in zooids 9-11, in single individuals 13-14.
Crawling on substratum.

Distribution
Holarctic.

Ecology
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
Tauber, 1879: 76; Sperber, 1948: 76; Sperber, 1950: 54; Brinkhurst and Jamieson, 1971: 315; Chekanovskaya, 1981: 252-253; Hrabe, 1981: 34, Pl. 3 Figs 2-3; Kasprzak, 1981: 91, Figs 165-166.

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