(Cernosvitov, 1937b)
Description
Small silvery white worms with opaque body (particularly in anterior region), due to presence of abundant granular coelomocytes. Chaetae 2(3) per bundle, peg-shaped with thinner tip, proximally uncinate. Dorsal bundles lacking in II (occasionally also in III), ventral bundles in XII at male pores. Clitellum covering XII-1/2 XIII; almost square gland cells 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 discoid to oval. 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 with 7-8 prominent diverticula, connected with oesophagus through short ental ducts; short ectal ducts thin but covered by distinct glands, ectal pore surrounded by a ring of larger glands. Large seminal vesicle often occupying all of IX-XI. Male funnels cylindrical or tapering towards either end, about four times as long as width, with regular collar of almost the same width. Vasa deferentia of medium length and narrow, penial bulbs large and compact. One mature egg present at a time. Length 8-10 mm, segment number 21-36. Can be confused with Marionina argentea, due to its silvery white colour and lack of dorsal chaetae in II; however, spermathecae are simple, without diverticula, in the latter species.
Burrowing in sediment.
Distribution
Western Palaearctic, North America.
Ecology
In marine and brackish-water littoral, seldom also in freshwater.
Reproduction
Sexual, with eggs laid in cocoons.
Literature
Southern, 1909: 158, Pl. XI Fig. 14; Stephenson, 1911a: 50, Fig. 9-11; Knöllner, 1935: 443-448, Figs 14-18; Cernosvitov, 1937b: 293; Nielsen and Christensen, 1959: 112-113, Figs 135-137; Kasprzak, 1986: 150-151, Figs 478-480.