title: Piscinoodinium, a fish-ectoparasitic dinoflagellate, is a member of the class dinophyceae, subclass gymnodiniphycidae: convergent evolution with Amyloodinium.
abstract: All dinoflagellates that infest the skin and gills of fish have traditionally been placed within the class Blastodiniphyceae. Their relatedness was primarily based upon a similar mode of attachment to the host, i.e., attachment disc with holdfasts. Results of recent molecular genetic analyses have transferred these parasites, including Amyloodinium, to the class Dinophyceae, subclass Peridiniphycidae. In our study, a small subunit rDNA gene from a parasitic dinoflagellate that has features diagnostic for species in the genus Piscinoodinium, i.e., typical trophont with attachment disc having rhizocysts, infesting the skin of freshwater tropical fish, places this organism within the dinophycean subclass Gymnodiniphycidae. This suggests a close relationship of Piscinoodinium spp. to dinoflagellates that include symbionts, e.g., species of Symbiodinium, and free-living algae, e.g., Gymnodinium spp. These molecular and morphological data suggest that evolution of this mode of fish ectoparasitism occurred independently in 2 distantly related groups of dinoflagellates, and they further suggest that the taxonomic status of parasites grouped as members of Piscinoodinium requires major revision.
authors.affiliation: Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, 27606 USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Levy
authors.forename: R Wayne
authors.initials: RW
authors.lastname: Litaker
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Goldstein
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Dykstra
authors.forename: Mark W
authors.initials: MW
authors.lastname: Vandersea
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Noga
mesh_terms: D000818:Animals; D005075:Biological Evolution; D016054:DNA, Protozoan / Q000032:analysis / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000032:analysis; D004141:Dinoflagellida / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D004478:Ectoparasitic Infestations / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D005393:Fish Diseases / Q000469:parasitology* / Q000473:pathology; D007695:Killifishes / Q000469:parasitology*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010802:Phylogeny; D011528:Protozoan Infections / Q000469:parasitology / Q000473:pathology; D011529:Protozoan Infections, Animal; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal