Reconsideration of the Gomphonema (Bacillariophyceae) species from Kolhapur, Northern Western Ghats, India: Taxonomy, typification and biogeography of the species reported by HP Gandhi

Unique environmental conditions in the Indian subcontinent create a diverse biogeographic region harboring with exceptional endemic biodiversity. Diatom studies in this region started in the early nineteenth century, with descriptions of many new species. H. P. Gandhi described nearly 300 new taxa beginning in 1952. The focus of this paper is to reconsider, typify and provide biogeographic notes on the Gomphonema species described by Gandhi from Kolhapur region of Northern Western Ghats. While Gandhi identified 11 taxa including two endemic taxa, we observed eight Gomphonema species from the same material, comprising six endemic and two cosmopolitan species. The morphology of these taxa is examined using both light and scanning electron microscopy and all taxa are compared with similar species. One of the eight species we observed is a new species, Gomphonema tamilensis sp. nov., and a new combination is established, Gomphonema lacusrankaloides comb. nov. Gomphonema tamilensis is similar to G. gandhii described from South India and Gomphocymbella species described from East Africa. Ultrastructural details of Gomphonema species from peninsular India shows morphologically similarities to members of this genus from Himalayan, Madagascar and African species, which could be reflective of sister taxon relationships, and merit further investigation.