THE PHYLOGENETIC RELATIONSHIP OF PFIESTERIA PISCICIDA, CRYPTOPERIDINIOPSOID SP. AMYLOODINOUM OCELLATUM AND A PFIESTERIA‐LIKE DINOFLAGELLATE TO OTHER DINOFLAGELLATES AND APICOMPLEXANS

Abstract

The taxonomic relationship between heterotrophic and parasitic dinoflagellates has not been studied extensively at the molecular level. In order to investigate these taxonomic relationships, we sequenced the small subunit (SSU) ribosomal RNA gene of Pfiesteria piscicida (Steidinger et Burkholder), a Pfiesteria-like dinoflagellate, Cryptoperidiniopsoid sp., and Amyloodinium ocellatum (Brown) and submitted those sequences to GenBank. Pfiesteria piscicida and Cryptoperidiniopsoid sp. are heterotrophic dinoflagellates, purportedly pathogenic to fish, and A. ocellatum, a major fish pathogen, has caused extensive economic losses in both the aquarium and aquaculture industries. The pathogenicity of the Pfiesteria-like dinoflagellate is unknown at this time, but its growth characteristics and in vitro food preferences are similar to those of P. piscicda. The SSU sequences of these species were aligned with the other full-length dinoflagellate sequences, as well as those of representative apicomplexans and Perkinsus species, the groups most closely related to dinoflagellates. Phylogenetic analyses indicate that Cryptoperidiniopsoid sp., P. piscicida, and the Pfiesteria-like dinoflagellate are closely related and group into the class Blastodiniphyceae, as does A. ocellatum. None of the species examined were closely re-1 . 3 This new species is being described by K. Steidinger, manuscript in preparation. lated to the apicomplexans or to Perkinsus marinus, the parasite that causes ''Dermo disease'' in oysters. The overall phylogenetic analyses largely supported the current class and subclass groupings within the dinoflagellates.

Prorocentrum rivalis sp. nov. (Dinophyceae) and its phylogenetic affinities inferred from analysis of a mixed morphological and LSU rRNA data set

“…Our analysis confirmed earlier reports that Prorocentrum species form two distinct ecological clades (Grzebyk et al 1998;Hoppenrath & Leander 2008;Litaker et al 1999;Murray et al 2005;Saldarriaga et al 2004): a benthic/epiphytic clade and a planktonic clade (Fig. 2).…”

5 The origin of the dinoflagellate plastid

“…For example, if all of the peridinin dinoflagellates formed a monophyletic group with the non-photosynthetic dinoflagellates as the outgroup then the acquisition of the peridinin plastid would be clear ( Fig.I.2). Phylogenetic trees do show a non-photosynthetic outgroup to the peridinin dinoflagellates, but all of these trees suffer from low bootstrap support and consequently this result must be interpreted with caution (Litaker et al 1999;Shalchian-Tabrizi 1999;Saldarriaga et al 2001). …”

Blastodinium galatheanumsp. nov. (Dinophyceae) a parasite of the planktonic copepodAcartia negligens(Crustacea, Calanoida) in the central Atlantic Ocean

“…The application of molecular techniques has dramatically changed our perception of the phylogeny and taxonomy of free-living dinoflagellates (Daugbjerg et al, 2000;Saldarriaga et al, 2004), and is also beginning to change our understanding of the parasitic species (Ku¨hn & Medlin, 2005;Litaker et al, 1999;Skovgaard et al, 2005;. Studies based on SSU rDNA data indicate that the Syndiniales is a valid taxonomic group in the sense that some syndinian representatives, i.e.…”