Denticula jamesrossensis, a new freshwater diatom (Bacillariophyta) species from the Maritime Antarctic Region

Abstract

During a survey of the freshwater diatom flora of James Ross Island (northern Weddell Sea) in the Maritime Antarctic Region, an unknown Denticula taxon was found in some lakes of Clearwater Mesa. The taxon showed some similarities with D. rainierensis Sovereign and D. subtilis Grunow but based on detailed light (LM) and scanning electron microscopy (SEM) the species showed sufficient morphological differences to separate it as a new species: D. jamesrossensis sp. nov. The new taxon is characterized, and distinguished from other species of the genus, by a typical constriction in the middle of the valve and a very high number of striae (up to 60 in 10 μm). So far, the new taxon has only been found on James Ross Island where it occurs in alkaline lakes with high specific conductance values.