(Southern, 1909)
Description
Small smooth pink worms. Body wall delicate, with deep intersegmental furrows in tail portion of preserved specimens. Prostomium conical, well separated from I by a furrow when preserved in alcohol. In anterior dorsal bundles 1-4 hair chaetae, 225-350 µm long, and 3-4 pectinates, 90-120 µm long, with equal teeth. In anterior ventral bundles 3-4 chaetae, 70-130 µm long, with slightly longer upper tooth. Clitellum short, in XI-XII. Male duct ending in thin chitinous truncated cone-shaped penial sheath (visible in compressed mature specimens). Spermathecae mostly lacking. Length 10-14 mm, segment number up to 70. Externally highly similar to Potamothrix hammoniensis and some of its congeners but usually smaller. When mature, distinguishable by presence of ordinary ventral chaetae in X while ventral bundles of XI are replaced by conical penial sheaths inside body. Short clitellum is also characteristic.
Burrowing in sediment.
Distribution
Holarctic, China, South Africa.
Ecology
In freshwater.
Reproduction
Sexual only. Prevailing lack of spermathecae must have been resulted in parthenogenesis. Eggs laid in small round cocoons with tough transparent shell and two very short appendages. Usually only two eggs per cocoon.
Literature
Southern, 1909: 140, Pl. VIII Fig. 6a-e; Brinkhurst and Jamieson, 1971: 497, Fig. 8.13A-F; Chekanovskaya, 1981: 345; Hrabe, 1981: 82-83, Pl. 13 Figs 7-8; Kasprzak, 1981: 159, Figs 545-557.