Revision of the Staurosirella leptostauron complex (Staurosiraceae, Bacillariophyta) in Europe with the description of three new species

Background and aims - Small-celled araphid diatoms form an important part of the diatom flora in our rivers and lakes. Although several of these species are frequently reported, their correct taxonomic identity is often obscured due to a lack of good knowledge of the original (type) material. Material and methods - Several historical (nineteenth century) original samples were retrieved from different European and North American diatom collections. The samples have been analysed using light (LM) and scanning electron Key results - Staurosirella crux comb. nov., based on Ehrenberg's Navicula crux, proved to be the oldest valid name for Staurosirella harrisonii, the latter now being considered a younger synonym. A new European species, S. neorhomboides sp. nov., is described to replace the name S. rhomboides, now considered a younger synonym of S. leptostauron. The North American populations of S. rhomboides and S. martyi differ sufficiently from the type populations and are described as new species: S. moralesii sp. nov. and S. manoyloviana sp. nov. The new combination Staurosirella informis comb. nov. is proposed for a taxon described in 1856 from the French Pyrenees as Odontidium informe. Staurosirella leptostauron turns out to be insufficiently described and is now documented for further use. Conclusion - The analysis of the original (type) material corrected several taxonomic errors and better characterised the morphology of several commonly observed Staurosirella species.