Rugogaster

The Rugogastridae are a taxonomic family of flatworms that consist of a single genus, Rugogaster, with only two species. The rugogastridae are parasites, and infect the rectal glands of various species of holocephalan fish. The family, genus and two species are characterised by a single row of rugae (transverse thickenings of the body surface), numerous testes, and two caeca. Species of the other three families of Aspidogastrea have a single caecum and either one or two testes.