Description of a new dinoflagellate with a diatom endosymbiont, Durinskia capensis sp. nov. (Peridiniales, Dinophyceae) from South Africa

Abstract

A new dinoflagellate Durinskia capensis Pienaar, Sakai et Horiguchi sp. nov. (Peridiniales, Dinophyceae), from tidal pools along the west coast of the Cape Peninsula, Republic of South Africa, is described. The dinoflagellate produces characteristic dense orange-red colored blooms in tidal pools. The organism is characterized by having a eukaryotic endosymbiotic alga. Ultrastructure study revealed the organism has a cellular construction similar to that of other diatom-harboring dinoflagellates. The cell is thecate and the plate formula is: Po, x, 4', 2a, 6'', 5c, 4s, 5''', 2'''', which is the same as that of Durinskia baltica, the type species of the genus Durinskia. D. capensis can, however, be distinguished from D. baltica by overall cell shape, the relative size of the 1a and 2a plates, the degree of cingular displacement, and the shape of the eyespot. Our molecular analysis based on SSU rDNA revealed that D. capensis is closely allied to D. baltica, thus supporting the assignment of this new species to this genus. This Durinskia clade takes a sister position to another diatom-harboring dinoflagellate clade, which includes Kryptoperidinium foliaceum and Galeidinium rugatum. Molecular analysis based on the rbcL gene sequence and ultrastructure study revealed that the endosymbiont of D. capensis is a diatom. The SSU rDNA gene trees indicated that four species with a diatom endosymbiont formed a clade, suggesting a single endosymbiotic origin.

Morphological differences and molecular phylogeny of freshwater blooming species, Peridiniopsis spp. (Dinophyceae) from China

“…The previous studies emphasized that the host phylogeny was indicative of a monophyletic group of diatom-harbouring dinoflagellates (Horiguchi and Takano 2006;Pienaar et al 2007;Takano et al 2008). However, the conclusion was not supported by all phylogenies in our study; therefore it was not entirely believable.…”

The Life History and Cell Cycle of Kryptoperidinium foliaceum, A Dinoflagellate with Two Eukaryotic Nuclei

“…This line of reasoning is consistent with the role of a sexual route in the life cycle of K. foliaceum, an organism that resides in shallow estuaries, that are highly and rapidly variable systems due to the strong effects of tides and river flow on their hydrological structure (Trigueros and Orive 2000). These habitats are common for other phylogenetically related species, such as G. quadrilobatum (Horiguchi and Pienaar 1994), D. capensis (Pienaar et al 2007), and P. quinquecorne (unpublished data), and may explain homothallism as the mating-type system of K. foliaceum. In homothallism, sexual zygotes can be produced by selffertilization, i.e., by the fusion of genetically identical gametes.…”

Endosymbiotic Gene Transfer in Tertiary Plastid-Containing Dinoflagellates

“…Dinotom plastids are complex and have preserved several features normally lost after the endosymbiotic event. In addition to the plastid itself, the endosymbiont has retained its nucleus, cytosol, cytosolic ribosomes, endoplasmic reticulum, and even mitochondria, all separated from the host components by a single membrane (70)(71)(72)(73)(74). The presence of a large endosymbiont nucleus actively transcribing genes means that the total RNA pool in dinotoms includes a mixture of dinoflagellate and diatom transcripts.…”