Nielsen and Christensen, 1959
Type species Marionina atrata Bretscher, 1903
Number of species 23. Seven species known from fresh waters of NWE:
Cernosvitoviella atrata (Bretscher, 1903)
Cernosvitoviella goodhui Healy, 1975
Cernosvitoviella immota (Knöllner, 1935)
Cernosvitoviella microtheca Rota and Healy, 1999
Cernosvitoviella minor Dózsa-Farkas, 1990
Cernosvitoviella palustris Healy, 1979
Cernosvitoviella sphaerotheca Healy, 1975
Some other species of the genus Cernosvitoviella are known only from soil in NWE and are therefore not included in the key.
Description
Small, mostly white, worms. Chaetae sigmoid, simple-pointed, with nodulus, arranged in fan-like bundles; their number per bundle variable, usually bigger in ventral bundles. Head pore on prostomium or in 0/1. Ventral chaetae absent from XII, on male pores. Clitellum in XII-XIII. Internal characters: No appendages on digestive tube. Dorsal blood vessel reaching backward at least as far as clitellar region. Nephridia consisting mainly of a bunch of nephridial canal, almost without interstitial tissue. Spermathecae not connected with oesophagus, without diverticula, without glands at ectal pore. Vas deferens often dilated ectally; no atrium or penial bulb; small gland cells surrounding male pore. Eggs in clitellar region only, innumerous. Similar to the genus Mesenchytraeus in fan-like bundles of sigmoid, nodulate chaetae; differing from it in smaller size, absence of egg sac reaching rearward from the clitellum, and many other details of internal anatomy.
Burrowing in sediment.
Distribution
Holarctic.
Ecology
In soil and freshwater.
Reproduction
Sexual only, with eggs laid in cocoons.
Literature
Roule, 1888: 1811; Michaelsen, 1889b: 28; Nielsen and Christensen, 1959: 37-38; Kasprzak, 1986: 102, Fig. 225.