Contribution to the inventory of Iberian diatoms: Encyonema nevadense S.Blanco & al. sp. nov. (Cymbellales, Gomphonemataceae)

The diatom Encyonema nevadense S.Blanco & al. sp. nov. is described as a new species, from epilithic samples collected from a high mountain pond in Sierra Nevada National Park. This taxon is characterized by the presence of narrow lanceolate valves with a moderate dorsiventrality, and the presence of areolae with irregular external openings. The type population is compared with Encyonema perpusillum (A.Cleve) D.G.Mann and its varieties, the morphologically closest species within the genus. The ecological and biogeographic implications of the discovery are briefly discussed.