2007 Volume 48 Issue 4 Pages 199-211
The genus Schizochytrium sensu lato has been characterized by successive binary division of its vegetative cells. However, the molecular phylogeny strongly suggests that this genus is not a natural taxon, because the original and recorded strains that have been identified as Schizochytrium spp. separately form three well-supported monophyletic groups in the 18S rRNA gene tree. These three groups are clearly distinguishable by their combined morphological characteristics and the profiles of the polyunsaturated fatty acids and carotenoid pigments they contain, although these are hard to distinguish using only a single feature. Therefore, three different genera are proposed to accommodate these three groups, i.e., Schizochytrium sensu stricto, Aurantiochytrium, and Oblongichytrium gen. nov.