Morphology and molecular phylogeny of Amphidiniopsis rotundata sp. nov. (Peridiniales, Dinophyceae), a benthic marine dinoflagellate

Abstract

Hoppenrath M., Selina M., Yamaguchi A. and Leander B. 2012. Morphology and molecular phylogeny of Amphidiniopsis rotundata sp. nov. (Peridiniales, Dinophyceae), a benthic marine dinoflagellate. Phycologia 51: 157–167. DOI: 10.2216/11-35.1A new dinoflagellate species within the benthic, heterotrophic, and thecate genus Amphidiniopsis was discovered, independently, in sediment samples taken on opposite sides of the Pacific Ocean: (1) the Vancouver area, Canada, and (2) Vostok Bay, the Sea of Japan, Russia. The cell morphology was characterized using light and scanning electron microscopy, and the phylogenetic position of this species was inferred from small-subunit ribosomal DNA sequences. The thecal plate pattern [formula: apical pore complex 4′ 3a 7″ 5c 5(6)s 5‴ 2‴′] and ornamentation, as well as the general cell shape without an apical hook or posterior spines, demonstrated that this taxon is different from all other described species within the genus. Amphidiniopsis rotundata sp. nov. was dorsoventrally flattened, 24.5–38.5 µm long, 22.6–32.5 µm wide. The sulcus was characteristically curved and shifted to the left of the ventral side of the cell. This work presents the first molecular study including a representative of the genus Amphidiniopsis, and led us to propose a new combination, Amphidiniopsis dragescoi comb. nov. (formerly Thecadinium dragescoi), and also suggests a close relationship between Amphidiniopsis, Herdmania (another benthic genus), and Archaeperidinium minutum (a planktonic species).