Dermocystidium is a genus of cyst-forming, eukaryotic fish parasites, the causative agents of dermocystidiosis.

Taxonomic history

The genus Dermocystidium was described in 1907. It was previously thought to be a genus of fungal parasites, related to the Thraustochytrida and Labyrinthulida (both those groups are now considered to be stramenopiles rather than fungi). Other biologists considered it to be a sporozoan protist. It was subsequently identified as one of a group of fish parasites (the "DRIP clade") of previously uncertain affiliation, which were later identified as nonanimal, nonfungal opisthokonts, and renamed as Ichthyosporea, and after expansion as Mesomycetozoa. Parasites of crustacea (Dermocystidium daphniae) and molluscs (Dermocystidium marinum) placed in this genus have been found to be likely a bacterium and an alveolate, respectively: Sayre, Gherna and Wergin (1983) concluded that Dermocystidium daphniae was likely identical to Pasteuria ramosa Metchnikoff, 1888, while D. marinum has been reclassified as Perkinsus marinus. The frog parasite Dermocystidium ranae has recently been segregated as Amphibiocystidium ranae.

Species