THE RECLASSIFICATION OFPFIESTERIA SHUMWAYAE(DINOPHYCEAE):PSEUDOPFIESTERIA, GEN. NOV.

Pfiesteria shumwayaeGlasgow et Burkholder is assigned to a new genusPseudopfiesteriagen. nov. Plate tabulation differences betweenPfiesteriaandPseudopfiesteriagen. nov. as well as a maximum likelihood phylogenetic analysis based on rDNA sequence data warrant creation of this new genus. The Kofoidian thecal plate formula for the new genus is Po, cp, X, 4′, 1a, 6′′, 6c, PC, 5+s, 5′′′, 0p, 2′′′′. In addition to having six precingular plates,P. shumwayaecomb. nov. also has a distinctive diamond or rectangular-shaped anterior intercalary plate. BothPfiesteriaandPseudopfiesteriagen. nov. are reassigned to the order Peridiniales based on an apical pore complex (APC) with a canal (X) plate that contacts a symmetrical 1′, four to five sulcal plates, and the conservative hypothecal tabulation of 5′′′, 0p, and 2′′′′. These morphological characters and the life histories ofPfiesteriaandPseudopfiesteriaare consistent with placement of both genera in the Peridiniales. Based on the plate tabulations forP.shumwayae, P. piscicida, and the closely related“cryptoperidiniopsoid” and“lucy” groups, the family Pfiesteriaceae is amended to include species with the following tabulation: 4-5′, 0-2a, 5-6′′, 6c, PC, 5+s, 5′′′, 0p, and 2′′′′ as well as an APC containing a pore plate (Po), a closing plate (cp), and an X plate; the tabulation is expanded to increase the number of sulcal plates and to include a new plate, the peduncle cover (PC) plate. Members of the family have typical dinoflagellate life cycles characterized by a biflagellated free-living motile stage, a varying number of cyst stages, and the absence of multiple amoeboid stages. [ABSTRACT FROM AUTHOR]