(Michaelsen, 1926a)
Description
Small papillate (or with smooth anterior half) worms. Tail region considerably thinner. Scattered small secretory papillae, with adhering foreign material, covering tail region in adults but whole body in young individuals. In anterior bundles 2-5 crotchets, about 50 µm long, with short equal teeth. In posterior segments mostly 1-2 simple crotchets per bundle, about 60 µm long, with prolonged sabre-like distal part. In transitional zone sometimes crotchets with two prolonged teeth, lower one being much thinner. No modified genital chaetae; no ventral chaetae in XI, at male pores; penes in very thin cuticular sheaths. Length 7-9 mm, segment number counted once as 46. Can be confused with small individuals of Limnodrilus when only anterior, smooth half of body is available, but the latter genus is characterized by thick-walled cylindrical penial sheaths. In comparison with papillate freshwater worms, lack of hair chaetae and presence of simple-pointed posterior crotchets are characteristic. The other species of Tubificoides, living in brackish and marine water, do not occur in freshwater habitats.
Burrowing in sediment.
Distribution
Both shores of the Northern Atlantic.
Ecology
In weakly brackish bays and river mouths, occasionally in almost freshwater.
Reproduction
Sexual only. Eggs laid in cocoons.
Literature
Michaelsen, 1926a: 22-28, Fig. A; Brinkhurst and Jamieson, 1971: 521, Fig. 8.14G-I; Chekanovskaya, 1981: 349-350, Fig. 177; Kasprzak, 1981: 166, Fig. 606; Baker, 1981: 564-568, Figs 1-2.