Michaelsen, 1908
Description
Medium-sized smooth pink worms. In anterior dorsal bundles 2-4 finely pilose hair chaetae, up to 500 µm long, and 3-5 pectinates, about 100 µm long, with equal main teeth and with several distinct intermediate teeth. Anterior ventral chaetae 3-5 per bundle, about 90 µm long, with slightly longer and thinner upper tooth, sometimes with short intermediate teeth. Both dorsal and ventral chaetae become less numerous, and their teeth equally short, in posterior segments. In XI, near male pores, sharp simple-pointed penial chaetae, 1-2 per bundle. Clitellum in XI-XII, spermathecal pores laterally of the unmodified ventral chaetae in X. Length about 15 mm, segment number about 50. A poorly known species. Immature individuals hardly distinguishable from many other species of Tubifex and Psammoryctides. When mature, distinguishes from them in having modified penial chaetae. In the genus Rhyacodrilus and other rhyacodrilins, penial chaetae are blunt, and their distal tips are located close together in each bundle, unlike Tubifex nerthus. The latter is also devoid of large coelomocytes characteristic of Rhyacodrilinae.
Burrowing in sediment.
Distribution
Europe.
Ecology
In fresh and slightly brackish water.
Reproduction
Sexual only. Eggs laid in cocoons.
Literature
Michaelsen, 1908: 155-159, Pl. 3 Figs 15-20; Brinkhurst and Jamieson, 1971: 458, Fig. 8.1KM; Chekanovskaya, 1981: 345-346, Fig. 174; Hrabe, 1981: 86, Pl. 14 Figs 7-16.