(Moore, 1894)
Description
Small leech-shaped but unpigmented worms, without prostomium or chaetae. Anteriormost four segments fused to form head. Posterior end is modified as sucker-like adhesive disk; ventral edge of mouth also acting as adhesive organ. Body racket-shaped: posterior portion of trunk expanded and flattened like a disk; first four trunk segments narrow, terete, double-ringed; head somewhat broader. Jaws with 4 (sometimes 5) slightly diverging teeth; outer pair of teeth symmetrical, middle ones unequal. Length 5.5 mm. Externally differing from other branchiobdellidans in NWE, in its racket-like body and in the shape of jaws.
Crawling like leech on the body of crayfish.
Distribution
Nearctic; recently introduced into Europe (Finland) with North American crayfishes. Probably introduced also to Sweden.
Ecology
In freshwater, living on external surface of crayfishes.
Reproduction
Eggs laid in cocoons attached with one end to body of crayfish.
Literature
Moore, 1894: 425-427, Pl. XII Figs 3a-e; Goodnight, 1940: 45-46, Fig. 13; Hobbs et al., 1967 : 64-65, Fig. 22; Holt, 1986: Fig. 6.