Genus Potamothrix

Vejdovsky and Mrázek, 1903

Type species Potamothrix moldaviensis Vejdovsky and Mrázek, 1903
Number of species 20. In NWE, six species:
Potamothrix bavaricus (Oschmann, 1913)
Potamothrix bedoti (Piguet, 1913)
Potamothrix hammoniensis (Michaelsen, 1901a)
Potamothrix heuscheri (Bretscher, 1900b)
Potamothrix moldaviensis Vejdovsky and Mrázek, 1903
Potamothrix vejdovskyi (Hrabe, 1941)

Description
Small to medium-sized smooth pink tubificids. Prostomium short conical, separated by a distinct furrow from I, in alcohol-preserved specimens. Body wall delicate, with deep intersegmental furrows on tail when preserved. Most species with hair and pectinate chaetae in dorsal bundles; bifid crotchets in ventral bundles. Furrowed spermathecal chaetae of different shape, in X. Male pores in XI, accompanied with a few ordinary or slightly modified crotchets. In internal reproductive system, very short or rudimentary vas deferens and long tubular atrium are highly characteristic of this genus. Immature individuals are very similar to those of several other tubificid genera bearing hair and pectinate chaetae in dorsal bundles.
Burrowing in sediment.

Distribution
Cosmopolitan, with most species in Europe and in the Ponto-Caspian basin.

Ecology
In fresh and brackish water.

Reproduction
Mostly sexual only, except for one species. Eggs laid in cocoons.

Literature
Eisen, 1879b: 9; Vejdovsky and Mrázek, 1903: 1; Brinkhurst, 1963: 47; Brinkhurst and Jamieson, 1971: 486-487; Chekanovskaya, 1981: 319-321; Hrabe, 1981: 76; Kasprzak, 1981: 154-155; Holmquist, 1985: 327-349, Figs 15-16, 20, 22C, 23F-H, 24H-J, 25; Finogenova and Poddubnaja, 1990: 1-82, Figs 1-14.

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