Holt, 1965
The single family Branchiobdellidae (but sometimes treated as five separate families!), with 21 genera and 148 species. In NWE, three genera with eight species.
Description
Small leech-shaped but unpigmented worms, without prostomium or chaetae, but with constant number of segments (15). 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. Two chitinized jaws (upper one and lower one) in mouth. One or two pairs of testes, in the fifth and/or sixth trunk segment(s). Male ducts either prosoporous or secondarily plesioporous (as in Branchiobdella); vasa deferentia enter unpaired atrium (named also spermiducal gland) in VI. Prostate, attached to atrium, need not be homologous to prostate gland of other oligochaetes. Ovaries in the seventh, unpaired spermatheca in the fifth body segment. Convergently similar to leeches, due to their epizoic way of life. Reproductive system similar to that of Lumbriculidae. Branchiobdellidans have been treated as a family of either Oligochaeta or Hirudinea, for a long time. Separated as an independent order of Clitellata, by Holt, 1965; divided into five families by Holt, 1986. For sake of convinience, all branchiobdellidans are treated as one family here, including Cambarincola mesochoreus belonging to the family Cambarincolidae, after Holt.
Crawling like leech on the body of crayfish.
Distribution
Holarctic; northern portion of the Sino-Indian Region.
Ecology
In freshwater, living as commensals or/and parasites on the body surface and gills of crayfishes and some other crustaceans.
Reproduction
Sexual only. Eggs laid in cocoons attached with one end to body of crayfish.
Literature
Holt, 1965: 30-31; Holt, 1986: 685; Gelder, 1996: 653-663.