Cellular and body scale structure of Heterocapsa ovata sp. nov. and Heterocapsa orientalis sp. nov. (Peridiniales, Dinophyceae)

Abstract Two new armoured dinoflagellate species, Heterocapsa ovata Iwataki & Fukuyo sp. nov. and Heterocapsa orientalis Iwataki, Botes & Fukuyo sp. nov., are described, and their body scale and cell morphology are illustrated using light, fluorescence, scanning electron and transmission electron microscopy. These species possess a thecal plate arrangement that is typical of the genus Heterocapsa: Po, cp, 5′, 3a, 7″, 6c, 5s, 5″′, 2″″; and they have triradiate three-dimensional body scales consisting of a reticulated basal plate, spine-like uprights, bars, etc. The cells of H. ovata and H. orientalis are not similar in shape to other described species of Heterocapsa, but are ovoid. In addition, the ultrastructure of the body scales of the two species is different from other Heterocapsa species: relatively simple in H. ovata, but more complex in H. orientalis.