Friend, 1911a, augm. Cernosvitov, 1937c
Description
Small white worms. Chaetae in symmetrical fan-like bundles, needle-shaped, tapering distally, by 3-6 in dorsal bundles, and by 4-8 in ventral bundles, 40-60 µm long; central chaetae in bundle often considerably shorter and thinner than lateral ones. Ventral chaetae lacking at male pores in XII. Clitellum in XII-1/2 XIII, gland cells can be arranged in transverse rows. Internal characters: Pharyngeal glands in three pairs, at 4/5-6/7, without dorsal connections. Coelomocytes oval, finely granulated. No intestinal or oesophageal diverticula. Transition between oesophagus and intestine abrupt, at 7/8. Blood colourless, dorsal blood vessel reaches backward to VIII only, with pulsating expansions in VI, VII and VIII. Spermathecae in V, consisting of very short ectal duct, only slightly dilated ampulla, and long ental duct; ental ducts of both sides join before falling into oesophagus from the dorsal side, at 5/6. Male funnels 1.5 times as long as width, the collar of same width. One mature egg present at a time. Length 5-10 mm, segment number 21-36. A variable species, differing from its congeners in simple digestive tract (without intestinal appendages), and in sharper, ectally tapering chaetae. With shorter central chaetae in bundles, Henlea perpusilla resembles many terrestrial species of the genus Fridericia. However, in Henlea perpusilla, chaetae are sharp-tipped, and their distal ends form a regular, slightly concave line. In Fridericia, chaetae are more blunt, with distal ends of smaller central chaetae lying much deeper in each bundle.
Burrowing in sediment.
Distribution
Holarctic, China and Japan.
Ecology
In soil, sometimes in freshwater near the shore.
Reproduction
Sexual, with eggs laid in cocoons.
Literature
Friend, 1911a: 466; Friend, 1913a: 84; Cernosvitov, 1937c: 191-205; Cernosvitov, 1942: 271; Nielsen and Christensen, 1959: 58-59, Figs 46-47; Kasprzak, 1986: 256-257, Figs 990-996.