Stylodrilus brachystylus

Hrabe, 1929a

Description
Small or medium-sized pink or yellowish red worms. Prostomium rounded. External secondary annulation beginning from IV. Chaetae two per bundle, sigmoid with nodulus, mainly bifid with shorter parallel upper tooth, but in foremost segments often simple, 55-110 µm long. In mature worms penes internal, sitting on muscular bulbs, 30-40 µm long, sometimes their tips slightly protruding from penial sacs in X. Spermathecal pores in IX, ventral. Clitellum in 1/2 IX-1/2 XII. In tail region, a single pair of short blind transversal appendages per segment, on dorsal blood vessel. Testes in IX and X; posterior pair of vasa deferentia penetrate dissepiment 10/11 twice. Atria in X pear-shaped, covered with high prostatic cells. Length 13-20 mm, segment number 55-75. Differing from congeners in large but hidden penes.
Burrowing in sediment.

Distribution
Europe.

Ecology
In freshwater, mainly in springs and brooks.

Reproduction
Sexual only. Eggs laid in cocoons.

Literature
Hrabe, 1929a: 10-14, Figs 1-4; Hrabe, 1981: 101, Pl. 18, Fig. 6; Cook, 1971a: 241, Figs 5.5F, 5.6H; Kasprzak, 1981: 197-198, Figs 789-795.

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