Piguet, 1906a
Description
Transparent worms, sometimes with brown pigment. Eyes present. Dorsal bundles beginning from VI, with 1-3 straight, 150-380 µm long, hair chaetae and 1-3 51-105 µm long sharp-tipped needle chaetae bearing distinct distal nodulus. Ventral chaetae by 2-5, always with upper tooth thinner and up to 1.5 times as long as lower one; in II-V 60-118 µm long, from VI on slightly thicker and 45-95 µm long. In mature individuals penial chaetae by 2-3, with reduced upper tooth. Stomachal dilatation abrupt. Length 1.5-6 mm, segment number in zooids 11-18, in single individuals 17-18. Differing from Nais barbata in having relatively longer hair chaetae and distinctly nodulate needle chaetae, as well as longer upper tooth in posterior ventral crotchets.
Crawling on substratum. Able to swim.
Distribution
Holarctic, South America, South Africa.
Ecology
In freshwater.
Reproduction
Mostly asexual, by paratomy (budding). Mature individuals and sexual reproduction rare or seasonal.
Literature
Piguet, 1906a: 238-241, Pl. X Figs 5-7, Pl. XI Figs 4, 6-7, Pl. XII Fig. 9; Sperber, 1948: 118-119; Sperber, 1950: 63, Fig. 12D-F; Brinkhurst and Jamieson, 1971: 339-340, Fig. 7.7B-E; Chekanovskaya, 1981: 223-224, Fig. 96; Hrabe, 1981: 46-47, Pl. 6 Figs 16-19; Kasprzak, 1981: 120-121, Figs 325-328.