A new species of Pleurosigma from Western Ghats, South India

A new species, Pleurosigma lange-bertalotii sp. nov., is studied with light and scanning electron microscopy and described from Western Ghats, South India. The new species possesses transverse striae pattern on the external valve surface, but internal valve views show oblique striae patterns. At present the species is assigned to the genus Pleurosigma due to the presence of oblique striation. The oblique striae pattern is continuous internally from the central nodule to the apices, and this helps to differentiate the new species from P obscurum. The new taxon is observed only from a forested, low electrolytic stream from South Western Ghats, South India. Recent studies on diatoms suggest that the Indian sub continent is a major geographic zone for many new diatoms, contributing to our understanding of the evolution of diatoms of this biogeographic region.