A new Stauroneis species (Bacillariophyceae) associated with a waterfall in Misiones province (northeastern Argentina)

During a survey of the diatoms present in aerophilic microhabitats associated with waterfalls in Misiones province (Argentina), aimed to explore the diatom flora occurring in these particular environments, we found a diatom belonging to the genus Stauroneis which does not match to previously recorded taxa and it is therefore described here as a new species, Stauroneis alegrensis. The new species was recorded from a sample of rock scrapings in a site affected by the waterfalls’ spray and documented with light and scanning electron microscopy. The new species was compared to other morphologically similar large species with pseudosepta from other regions of the world. Although sharing with the latter the main features of valve morphology, S. alegrensis can be distinguished by its unique combination of morphometric characters.