An unusual freshwater diatom with bilobate ends from the Mid-Miocene of East Antarctica: Staurosirella tigris sp. nov. (Fragilariaceae, Bacillariophyta)

A new species of araphid diatoms with bilobate ends is described as Staurosirella tigris sp. nov. It was found in mid Miocene glacial-lacustrine sediments in the Friis Hills, Antarctica. The new diatom is placed in Staurosirella because it has striae composed of apically-oriented lineolae, separated by long, thin vimines, and it lacks rimoportulae. It can be easily distinguished by its rectangular valve shape with bilobate ends, differing from Staurosirella grunowii, another four lobed Miocene species, by having a rectangular central portion to its valves instead of being cross-shaped with the four lobes arising from a common central area. Also, the distribution of the new species is different, to date only being found in Antarctica, while S. grunowii is restricted to the Northern Hemisphere.