Pileidinium ciceropsegen. et sp. nov. (Dinophyceae), a sand-dwelling dinoflagellate from Palau

A new sand-dwelling dinoflagellate, Pileidinium ciceropse Tamura et Horiguchi gen. et sp. nov., is described from a sandy beach on Mecherchar Island, Republic of Palau, using light and electron microscopy. The cell is laterally compressed and consists of a small epitheca and a large hypotheca. It has a yellow-brown chloroplast and a spherical pyrenoid. This dinoflagellate possesses ornamented thecal plates and an unusual thecal plate arrangement of 1′, 5′′, 4c, 4s, 5′′′, 1′′′′. The cingulum is incomplete and does not encircle the entire cell. Transmission electron microscopy reveals that the cell possesses typical dinoflagellate organelles. Phylogenetic analysis based on SSU rDNA did not demonstrate a consistent phylogenetic position of Pileidinium ciceropse within the Dinophyceae and therefore affinities with existing families could not be determined.