Observations on the pigmentation of the monogeneans, Anoplodiscus spp. (family Anoplodiscidae) in different microhabitats on their sparid teleost hosts.

The monogeneans Anoplodiscus australis and A. cirrusspiralis infect the fins of their respective hosts, the yellowfin bream, Acanthopagrus australis, and the snapper, Pagrus auratus. In these habitats the adult parasite contains melanin-like pigment deposits within the body. Very young parasites lack the pigment but deposits of pigment appear and coalesce into dense deposits within the parasite as it grows. The evidence suggests that the pigment is synthesized within the body of the parasite rather than acquired through feeding on the host epidermis. However, adults of Anoplodiscus cirrusspiralis from the nares of snapper lack this pigment, which suggests that environmental cues may promote the production of pigment as a possible aid to camouflage.