Sperber, 1948
Description
Transparent whitish worms, sometimes with brown pigment anteriorly. Eyes present. Dorsal bundles beginning from VI, with 1-2 hair chaetae, 114-225 µm long, and 1-2 blunt needle chaetae, 51-90 µm long. In needle chaetae, nodulus at 1/5-1/4 from distal end. Ventral chaetae in II-V by 2-8, 83-135 µm long, with parallel teeth of equal thickness but upper tooth twice as long. Beginning from VI ventral chaetae by 3-7, 63-108 µm long, thicker but similarly with twice as long upper tooth. In mature individuals, hooked 93 µm long penial chaetae, by 2-3. Stomachal dilatation abrupt. Length 3.6-4.8 mm, segment number in zooids 14-19, in single individuals 19-27. Similar (and probably closely related) to Nais behningi but with teeth of about equal thickness and not so strongly curved, in anterior ventral chaetae.
Crawling on substratum.
Distribution
Europe, Great Lakes of North America.
Ecology
In freshwater, mostly in cool streams.
Reproduction
Mostly asexual, by paratomy (budding). Mature individuals and sexual reproduction rare or seasonal.
Literature
Sperber, 1948: 113-116, Figs 11D-F, 12A, Pl. VII Figs 6-7, Pl. VIII Figs 1-3; Sperber, 1950: 61-62, Fig. 11D-F; Brinkhurst and Jamieson, 1971: 337-338, Figs 7.6Q-S, 7.7A; Hrabe, 1981: 48, Pl. 9 Figs 7-9; Kasprzak, 1981: 121-122, Figs 329-331.