Studies on type material from Kutzing's diatom collection I: Synedra vitrea Kutzing, with comments on Ulnaria fragilariaeformis (FE Fritsch and MF Rich) DM Williams, nov. stat. et nov. comb. and Ulnaria undulata (Rabenhorst) DM Williams, nov. stat. et nov. comb.

Original material of Ulnaria (Synedra) vitrea has been examined using light and electron microscopy. Valve and girdle morphology are documented, comments are made on various synonyms and other published, named varieties of Synedra vitrea. As Synedra vitrea is often considered a synonym of Ulnaria amphirhynchus or Ulnaria ulna var. amphirhynchus, two additional taxa are discussed: Ulnaria fragilariaeformis (F.E. Fritsch and M.F. Rich) D.M. Williams, nov. stat. et nov. comb. and Ulnaria undulata (Rabenhorst) D.M. Williams, nov. stat. et nov. comb. Both were previously considered to be varieties of Ulnaria amphirhynchus (basionym: Synedra amphirhynchus Ehrenberg). Ulnaria amphirhynchus has not yet been studied in detail. The characters of the genus Ulnaria are outlined once again and discussed with respect to characterising taxa (of whatever rank) rather than, or in addition to, describing them.