Mayfly types and additional material (Insecta: Ephemeroptera) examined by F. - J. Pictet and A. - E. Pictet, housed in the Museums of Natural History of Geneva and Vienna Author Sartori, Michel Musée cantonal de zoologie, Palais de Rumine, Place Riponne 6, CH- 1005 Lausanne, Suisse. & Département d’Ecologie et d’Evolution, Biophore, Université de Lausanne, CH- 1015 Lausanne, Suisse. Author Bauernfeind, Ernst Naturhistorisches Museum Wien, Burgring 7, A- 1010 Wien, Österreich. E-mail: ernst. bauernfeind @ nhm-wien. ac. at * Corresponding author: michel. sartori @ vd. ch ernst.bauernfeind@nhm-wien.ac.at text Revue suisse de Zoologie 2020 127 2 315 339 journal article 119274 10.35929/RSZ.0022 8839740a-00d8-44ff-b6cf-5cee99c19643 0035-418 5743794 Cloe undata F.-J. Pictet, 1843 Cloe undata F.-J. Pictet, 1843 -1845: 264-265 , pl. 41, fig. 6. Callibaetis undatus . – Eaton, 1885: 196 (transfer). Accepted name: Cloe undata F.-J. Pictet, 1843 nom. dub . Locus typicus: “… elle provient du Mexique ”. Type material: Holotype [by monotypy], female imago, not traced and most probably lost. Remarks: The specimen F.-J. Pictet examined was already in bad condition and was sent by Mr Coulon from Neuchâtel . The specimen is neither housed in the Natural History Museum of that town (J.P. Haenni in litt.) nor in the MHNG. The taxon is only known from F.-J. Pictet’s description and illustration, and the name Cloe undata Pictet, 1843 should be considered a nomen dubium .