Morphology and taxonomy of Eunotia clevei

Eunotia clevei Grunow ex Cleve was collected as an epiphyte on aquatic moss es and macroalgae from the Ravdangiin Bulag mineral spring in western Mongo lia. E. clevei is widely reported but usually rare in many north temperate large-lake systems and fossil deposits. This taxon is characterized by its large size, two rimoportulae per valve, a small pseudoseptum that is overla pped by the valvocopula, spinules on the dorsal and ventral valve margins, an internal proximal raphe hook, sternum on the valve face, coarsely areola te striae in LM, and epithemioid frustular symmetry (heteropolarity in the transapical plane) because of dorsally expanded mantles and cingular elemen ts. This combination of characters clearly differentiates E. clevei from Eu notia sensu stricto; however, some of these characters are shared with othe r eunotioid genera such as Desmogonium, Semiorbis, Peronia, Actinella, and Eunophora, suggesting that Eunotia clevei, its varieties, and allied taxa m ay be better placed within a new genus.