Lafont and Juget, 1993
Description
Smooth pink worms, without hair and pectinate chaetae. Prostomium prolonged. Locomotory chaetae 50-60 µm long; their number decreases caudad, from 3-7 to 2-4. Ventral chaetae of II-VIII (II-XII in immature individuals) and of the tail region with upper tooth 2-3 times as long as lower one; in the midbody (about XIII-XL), ventral chaetae with equal teeth, or with upper tooth slightly shorter and thinner. Dorsal chaetae in anterior region and midbody also with more or less equal teeth, but beginning from about XXX, with much longer upper tooth alike the posterior ventral ones. Two kinds of modified genital chaetae present. Spermathecal chaetae in X, one per bundle, 70-75 µm long, with long spoon-like upper tooth and rudimentary lower tooth. Similar modified chaetae in IX and often also in XII. Penial chaetae in XI, 3-5 per bundle, 60-80 µm long, almost straight, blunt-tipped or bifid with rudimentary upper tooth. Dark chloragogen tissue covering oesophagus from V. Abundant large coelomocytes in body cavity. Male pores in XI on protuberances. Length 6-7 mm, segment number 49-53. The species is easily recognizable by its peculiar chaetae. It differs from the most related species, Rhyacodrilus carsticus, by different distribution of two types of locomotory chaetae along the body, by presence of modified chaetae of the spermathecal type in IX-X and XII (instead of X only), by more anterior beginning of chloragogen tissue, and by smaller size.
Burrowing in sediment.
Distribution
France.
Ecology
In freshwater, in streams, rare.
Reproduction
Sexual only. Eggs laid in cocoons.
Literature
Lafont and Juget, 1993: 115-123, Figs 1-4.