「Biology of crayfish worms (Annelida: Clitellata: Branchiobdellida)」
 

Stuart Gelder (Professor Emeritus, University of Maine at Presque Isle, USA)

Branchiobdellidans are leech-like, obligate ectosymbionts living primarily on astacoidean crayfish. Their anatomy is briefly described as it differs from both oligochaetes and leeches. Clitellates are hermaphrodites and cross-fertilization results in cocoons being attached to a live host. Members have a pair of sclerotized jaws to assist in feeding on a largely opportunistic diet, although some species do show food preferences. Endemic branchiobdellidan-host symbioses are found in Holarctic freshwater habitats, specifically in East Asia, North America, and the Euro-Mediterranean region. Recent commercial translocations of North American crayfishes have resulted in their symbionts being reported as exotic species in East Asia and Europe. Branchiobdellidan 
taxonomy consists of the order Branchiobdellida, the amily Branchiobdellidae, and five subfamilies with a total of 22 genera and approximately 145 species. A comparison of the past taxonomic phylogeny and a recent cladogram of the Branchiobdellida will be described.