Morphological and molecular characterization of Teleaulax gracilis sp. nov. and T. minuta sp. nov. (Cryptophyceae)

Teleaulax is a genus of delicate cryptophytes that are common and sometimes abundant in marine samples. Previous to this study, only three species (Teleaulax acuta, T. amphioxeia and T. merimbula) were known in the genus. Here, two new species were described from strains isolated from plankton samples collected at the seaward end of the Nervioi-Ibaizabal River estuary (south-eastern Bay of Biscay). They were examined by light microscopy and scanning and transmission electron microscopy, and the nuclear 18S rDNA was sequenced to infer the molecular phylogeny. The species of this genus have been distinguished by size, shape (especially of the cell anterior and posterior), swimming behaviour, morphology of the posterior band and the relative extension of the furrow. The most characteristic traits of Teleaulax gracilis sp. nov. were the cell anterior, that was only slightly rostrate, and the shape of the cell posterior, which tapered off gradually in form of a wedge and finished in a pointed antapex sustained by a V-shaped band. Teleaulax minuta sp. nov., with a length of 5-6.8 mu m, is the smallest within the genus and lacks a posterior band. Common features shared with other congeners are, among others, the long furrows, the more or less rostrate cell anteriors and tapered posteriors, a sheet-like internal periplast component thinner than the plasma membrane and the thylakoids arranged in stacks of three.