(Michaelsen, 1889a)
Description
Small silvery white worms with opaque body, due to presence of abundant granular coelomocytes. Chaetae 2 (seldom 3) per bundle, peg-shaped with thinner tip, proximally uncinate, 35-45 µm long. Dorsal bundles lacking from II, ventral bundles lacking from XII at male pores. Clitellum covering XII-1/2 XIII; gland cells are few in number and large, arranged in transverse rows. Internal characters: The first two pairs of pharyngeal glands fused dorsally, the third pair free and longitudinally directed in VI. Coelomocytes ovoid. Chloragogen cells present from VII, with refractile globules alike those in coelomocytes. No appendages on digestive tube. Blood colourless, dorsal vessel reaches rearward to XIII. Spermathecal ampullae in V without diverticula, ovoid or roundish, connected with oesophagus through short ental ducts; short and stout ectal ducts covered by small, indistinct glands; ectal pore surrounded by a small ring of glands. No seminal vesicle. Male funnes cylindrical or pear-shaped, with regular collar of almost the same width. Vasa deferentia long and narrow, penial bulbs compact. One mature egg present at a time. Length 4-7 mm, segment number 19-30. Can be confused with Marionina southerni due to silvery white colour and lack of dorsal chaetae in II; however, spermathecae are equipped with numerous prominent diverticula in the latter species.
Burrowing in sediment.
Distribution
Holarctic.
Ecology
In soil, also on shores and in freshwater.
Reproduction
Sexual, with eggs laid in cocoons.
Literature
Michaelsen, 1889a: 15, Fig. 6; Nielsen and Christensen, 1959: 113-114, Figs 138-141; Chekanovskaya, 1981: 393; Kasprzak, 1986: 151-152, Figs 481-492.