Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp. is erected to accommodate this species. Pentaplacodinium saltonense differs from Protoceratium reticulatum (Claparède et Lachmann 1859) Bütschli 1885 in the number of precingular plates (five vs. six), cingular displacement (two widths vs. one), and distinct cyst morphology. Incubation experiments (excystment and encystment) show that the resting cyst of Pentaplacodinium saltonense is morphologically most similar to the cyst-defined species Operculodinium israelianum (Rossignol, 1962) Wall (1967) and O. psilatum Wall (1967). Collections of comparative material from around the globe (including Protoceratium reticulatum and the genus Ceratocorys) and single cell PCR were used to clarify molecular phylogenies. Variable regions in the LSU (three new sequences), SSU (12 new sequences) and intergenic ITS 1–2 (14 new sequences) were obtained. These show that Pentaplacodinium saltonense and Protoceratium reticulatum form two distinct clades. Pentaplacodinium saltonense forms a monophyletic clade with several unidentified strains from Malaysia. LSU and SSU rDNA sequences of three species of Ceratocorys (C. armata, C. gourreti, C. horrida) from the Mediterranean and several other unidentified strains from Malaysia form a well-supported sister clade. The unique phylogenetic position of an unidentified strain from Hawaii is also documented and requires further examination. In addition, based on the V9 SSU topology (bootstrap values >80%), specimens from Elands Bay (South Africa), originally described as Gonyaulax grindleyi by Reinecke (1967), cluster with Protoceratium reticulatum. The known range of Pentaplacodinium saltonense is tropical to subtropical, and its cyst is recorded as a fossil in upper Cenozoic sediments. Protoceratium reticulatum and Pentaplacodinium saltonense seem to inhabit different niches: motile stages of these dinoflagellates have not been found in the same plankton sample.
Bibliographical noteFunding Information:
V.P. and M.J.H. each acknowledge support from a Discovery Grant of the Natural Sciences and Engineering Research Council of Canada (NSERC) . K.B.A. and M.F. were supported by the Instituto Nacional de Investigación y Tecnología Agraría y Alimentaria of the Spanish Government (project RTA2005-00109-00-00). CINVESTAV, Merida is thanked for supplying information about the Yucatan samples. Beatriz Paz is acknowledged for interesting discussions on toxicity. Anke Kremp, Maija Hutunnen, Jacob Larsen, Paul Hargraves and Ximena Vivanco kindly provided plankton samples. Nancy Lewis and Margaret Beaton generously shared information on strains from Nova Scotia, Canada. Captain Brown, crew of the MSV Strickland, Ms. Sarah Thornton, and EOS313-2010 (University of Victoria) students are all thanked for their participation in sediment sample collection. Paul Hargraves kindly provided SEM images of P. saltonense from cultures established from the Indian River Lagoon.[SS]
- Precingular plates
- Salton Sea