Bolidomonas: A new genus with two species belonging to a new algal class, the Bolidophyceae (Heterokonta)

A new algal class, the Bolidophyceae (Heterokonta), is described from one g enus, Bolidomonas, gen, nov., and two species, Bolidomonas pacifica, sp, no v and Bolidomonas mediterranea, sp, nov., isolated from the equatorial Paci fic Ocean and the Mediterranean Sea, respectively. Both species are approxi mately 1.2 mu m in diameter and have two unequal flagella; the longer flage llum bears tubular hairs, whereas the shorter is smooth. The flagellar basa l apparatus is restricted to two basal bodies, and there is no transitional helix. Cells are naked, devoid of walls or siliceous structures. The inter nal cellular organization is simple with a single plastid containing a ring genophore and a girdle lamella, one mitochondrion with tubular cristae, an d one Golgi apparatus close to the basal bodies. The Mediterranean and the Pacific species differ in the insertion angle between their flagella and th eir pattern of swimming, these differences possibly being linked to each ot her. Analyses of the SSU rDNA gene place the two strains as a sister group to the diatoms, Moreover, pigment analyses confirm this position, as fucoxa nthin is found as the major carotenoid in both lineages. These data strongl y suggest that the ancestral heterokont that gave rise to the diatom lineag e was probably a biflagellated unicell.