The antarctic diatomsThalassiosira dichotomica(Kozlova) comb. nov. andT. ambiguakozlova

摘要

Two small antarctic diatoms, usually missed by traditional collection methods, have been studied in light and electron microscopes.Porosira dichotomicahas been transferred toThalassiosirasince its valve structure and process pattern agree better with that genus.T. dichotomicais unusual in that some lines of areola walls are extended, sail-like, out from the valve, supporting Kozlova's original drawings.T. ambigua, the smaller of the two, has many similarities in structure withT. dichotomica, but has granules on the margin, lacks the sail-like structures on the valve, and has minor differences in processes and areola size. Bands stay together inT. ambiguaand show more fine structure than many species in the genus.