Ellis, 1919
Type species Xironogiton oregonensis Ellis, 1919
Number of species 5. One species known from NWE:
Xironogiton instabilis (Moore, 1894)
Description
Small leech-shaped but unpigmented worms, without prostomium or chaetae. The 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. Posterior portion of trunk depressed. Two pairs of testes. Atrium (spermiducal gland) not bifurcated; bursa large, spherical to asymmetrical; penis muscular, protrusible. Spermatheca small. Differing from the other branchiobdellidan genera in the combination of characters of reproductive system.
Crawling like leech on the body of crayfish.
Distribution
Nearctic; some species recently introduced into Europe with North American crayfishes.
Ecology
In freshwater, living on external surface of crayfishes.
Reproduction
Sexual only. Eggs laid in cocoons attached with one end to body of crayfish.
Literature
Ellis, 1919: 247-248; Goodnight, 1940: 43; Holt, 1986: 688.