Stigmagloia lobbanii gen. et sp. nov. (Bacillariophyceae, Mastogloiales), a new stigma-bearing diatom genus separated from Mastogloia

The genus Mastogloia comprises mainly marine diatoms with a modified and specialized valvocopula called partecta. We isolated a new species, morphologically similar to M. cyclops, from the coastal waters of Viet Nam. A detailed study using light and scanning electron microscopy as well as molecular phylogenetic analysis based on SSU rDNA and rbcL sequences led us to describe a new genus and species, Stigmagloia lobbanii gen. et sp. nov. The main difference between Stigmagloia and Mastogloia is the presence of a stigma. The differences between S. lobbanii and M. danseyi, the type species of Mastogloia, are discussed. Mastogloia cyclops is transferred to Stigmagloia and a new combination, S. cyclops comb. nov., is proposed.