Brachysira heteropolaris, a new diatom (Brachysiraceae, Bacillariophyta) species observed in an historic Weissflog slide from Scotland (UK)

During the analysis of an historic slide of Loch Canmor, Aberdeenshire (Scotland, UK) prepared by Eugene Weissflog and conserved in the Van Heurck collection (BR, Belgium), an unknown, heteropolar Brachysira taxon was observed that could not be identified using the currently available literature. The new species, described as Brachysira heteropolaris sp. nov., is characterised in having a strictly heteropolar, broadly lanceolate valve outline with non-protracted, acutely rounded apices. The new species was observed in a dystrophic-oligotrophic, weakly acidic lake, based on the analysis of the composing diatom flora, dominated by several Brachysira species, Gomphonema coronatum and Encyonopsis cesatii var. geitleri.