(Stolc, 1886)
Description
Medium-sized smooth pink worms. Body, particularly tail region, very long and thin, thread-like, consisting of extended segments. Hair chaetae on forebody 2-5 per bundle and 200-500 µm long, behind clitellar segments by 1-3 and extremely long (700-900 µm), 4-5 times as long as body diameter, thereby thin and flexible. Pectinate chaetae in anterior dorsal bundles by 2-3, with 1-2 intermediate denticles, bayonet-shaped. Ventral chaetae on forebody by 1-4 per bundle, with slightly longer upper tooth; further rearward teeth equally long. No modified genital chaetae. Male pores in XI. Length up to 70 mm, segment number up to 170. Easily recognizable by body shape and by long flexible hair chaetae. In another common tubificid with conspicuous erect hair chaetae in posterior segments, Psammoryctides albicola, they are thick and stiff. The rare, subterranean Krenedrilus sergei reveals very long, flexible hair chaetae; however, this worm is very small and equipped with modified genital chaetae. The only tubificid with similar thread-like body shape, Limnodrilus udekemianus, is devoid of any hair chaetae.
Burrowing in sediment.
Distribution
Palaearctic, Great Lakes of North America, Lake Titicaca in South America.
Ecology
In freshwater.
Reproduction
Sexual only. Eggs laid in cocoons.
Literature
Stolc, 1886: 646; Michaelsen, 1901a: 68-69; Brinkhurst and Jamieson, 1971: 456-457, Fig. 8.1E-G; Chekanovskaya, 1981: 340-341; Hrabe, 1981: 85, Pl. 14 Figs 1-6; Kasprzak, 1981: 172, Figs 644-649.