Stauroneis stebbinsgulchensis sp. nov. (Bacillariophyta: Naviculales), a new pseudoaerial diatom from a lithophytic iron-oxidizing bacterial biofilm and groundwater seep at Stebbins Gulch Natural Area, Ohio, USA

As one of the most diverse groups of algae, diatoms seemingly speciate with every niche opportunity. When managed or preserved for natural conditions, aerophilic habitats such as wet walls, seeps, and springs provide unique niche space for diatom diversification. With over 360 species, the genus Stauroneis occupies a wide variety of subaerial, pseudoaerial, terrestrial, limnoterrestrial, and aquatic niches on every continent, with many described as endemic to their area of discovery. Here we document the unique ecology and describe a new species of Stauroneis occurring within an iron-rich wet wall biofilm and groundwater seep located at Stebbins Gulch on the Holden Arboretum in Ohio, USA. Comparisons of multiple cryptic species are given while highlighting subtle but key differences across populations. Distinguished by an uncommon habitat, cell measurements, valve shape and appearance of the stauros, the discovery of this new specialized species highlights the importance of preserved natural areas to the maintenance of global biodiversity.