Dózsa-Farkas, 1992
Description
Small white worms. Chaetae by 2-3, straight, ~55 µm long. No ventral bundles in XII, at male pores. Clitellum extends over XII-1/2 XIII; gland cells arranged in transverse rows, with clear interspaces. Internal characters: Three pairs of pharyngeal glands in 4/5-6/7, without dorsal junctions; small ventral lobes in V and VI. Coelomocytes oval, with light granules. Chloragogen cells on oesophagus beginning from V, forming a dense layer in VII. No appendages on oesophagus and intestine but a pair of peptonephridia attached to the back side of pharynx, as unbranched tubes. Blood colourless, dorsal vessel reaching backward to XIII. Spermathecae in V with well differentiated, ovoid or spherical ampulla, short ental duct communicating with oesophagus, and rather long ectal duct densely covered with glands; separate small glands present also at spermathecal pore. Male funnels small, pear-shaped or cylindrical, with regular collar of about the same width. Vasa deferentia narrow, of medium length. Penial bulbs small and compact. One, rarely two, mature eggs at a time. Length ~3 mm, segment number 22-29. The species was originally described under the name Enchytraeus minutus by Nielsen and Christensen, 1961. This name appeared to have already been used for another taxon by Tauber, 1879; therefore Dózsa-Farkas, 1992 renamed the worm Enchytraeus christenseni. Externally similar to another very common small enchytraeid, Enchytraeus buchholzi, but differing from it in the shape of spermathecae.
Burrowing in sediment.
Distribution
Holarctic.
Ecology
In soil, sometimes also in freshwater.
Reproduction
Sexual, with eggs laid in cocoons.
Literature
Tauber, 1879: 72; Nielsen and Christensen, 1961: 17-18, Fig. 12; Kasprzak, 1986: 194-196, Figs 711-716; Dózsa-Farkas, 1992: 19.