(Piguet, 1913)
Description
Small smooth, pink worms. Prostomium short conical, separated by a distinct furrow from I, in alcohol-preserved specimens (except in fresh head regenerates). Body wall delicate, with deep intersegmental furrows on tail when preserved. In anterior dorsal bundles 3-5 smooth hair chaetae, 360-382 µm long, and 3-4 pectinate chaetae, 102-115 µm long, with upper tooth slightly longer, and with short fine intermediate teeth. Anterior ventral chaetae by 2-5, 102-113 µm long, with longer upper tooth. In mature specimens uniform genital chaetae in three segments, VII-IX (seldom in IX-XI), or in some of them only, highly asymmetrical, scalpel- or beak-shaped, 72-140 µm long. Male pores in IX, two pairs of spermathecal pores in VII and VIII. Length 10-18 mm, segment number 72-118 when mature. Potamothrix bedoti is easy to identify when mature, due to the particular shape of its genital chaetae, and a forward shift of whole reproductive apparatus by two segments. It has sometimes been treated erroneously as a synonym of Potamothrix bavaricus, in spite of the different shape and position of the genital chaetae. Immature specimens are very similar to young Potamothrix hammoniensis and some other congeners.
Burrowing in sediment.
Distribution
Europe, Great Lakes of North America.
Ecology
In freshwater.
Reproduction
Asexual reproduction by architomy (fragmentation) prevailing. Mature specimens found most often in springs where architomy is inhibited by permanently low temperature. Eggs laid in cocoons with thin transparent shell.
Literature
Piguet, 1913: 124-126, Fig. 4; Timm, 1970: 65, Figs 12-13; Timm, 1972: 237-241; Chekanovskaya, 1981: 321-322, Fig. 155; Hrabe, 1981: 80-81, Pl. 13 Figs 1-3, 6 ; Kasprzak, 1981: 156-157, Figs 524-525.