(Michaelsen, 1888a)
Description
Medium-sized white or yellowish worms. Chaetae sigmoid, sharp-pointed, without nodulus, by 2-3 per bundle (often 2 in anterior dorsal bundles), 40-110 µm long. Ventral chaetae absent at male pores. Owing to prevailing asexual reproduction by fragmentation, regenerating anterior or posterior ends often present; in sexually mature individuals, clitellum with male pores often shifted forward (with male pore usually in IX, sometimes in VIII or X). Clitellar glands arranged in transverse rows. Internal characters: Pharyngeal glands in up to 5 pairs (the posterior pairs can be reduced in mature individuals), on dissepiments 4/5-8/9; ventral lobes well developed. Coelomocytes variable: oval, pear-shaped or spindle-shaped. No appendages on digestive tube. Blood colourless, dorsal blood vessel can be observed up to XIII-XVIII. Spermatheca not connected with oesophagus, can extend backwards up to IX, consisting of roundish ampulla with gradual transition into long narrow duct. Duct reveals an almost spherical bulboid dilatation containing transversal sperm ring in its middle portion. Large gland present at spermathecal pore in 4/5. Male funnels tubular, three times as long as width; vasa deferentia long and narrow. Penial bulbs small and compact. Length 15-25 mm, segment number 40-65 (can be less in regenerating fragments). Cognettia glandulosa differs from the related Cognettia sphagnetorum in much larger pharyngeal glands having both dorsal and ventral lobes filling most of body cavity in the corresponding segments. The number of chaetae (two) in anterior dorsal bundles also can be helpful.
Burrowing in sediment.
Distribution
Holarctic.
Ecology
In soil and in freshwater near the shore.
Reproduction
Mostly asexual, by architomy (fragmentation). Mature individuals and sexual reproduction rare, with eggs laid in cocoons.
Literature
Michaelsen, 1888a: 490, Fig. 2; Nielsen and Christensen, 1959: 43-44, Fig. 30; Chekanovskaya, 1981: 399-400, Fig. 202; Kasprzak, 1986: 125-126, Figs 335-337.