The Ephemeroptera (Hexapoda, Insecta) from the Lower Cretaceous Crato Formation (NE Brazil): a new genus and species, and reassessment of Costalimella zucchii Zamboni, 2001 and Cratogenites corradiniae Martins-Neto, 1996

Abstract

A new genus and species of Ephemeroptera, Astraeoptera cretacica gen. et sp. nov., is described from the Lower Cretaceous limestone of the Crato Formation (Brazil). The new taxon has the following diagnostic characters: veins MP2 e CuA straight at their bases, MA branching in the apical half of wing length, CuA not forked, cubital field with longitudinal veins sub-parallel to CuA. It was compared with other adult mayflies worldwide, both fossil and extant, and could not be assigned to any known ephemeropteran family. In addition, holotypes of other two mayfly species were reanalyzed, resulting in taxonomical changes. A new description of the Costalimella zucchii Zamboni, 2001 holotype is provided, indicating its placement within Hexagenitidae, rather than Siphlonuridae, as previously proposed. We also reanalysed the holotype of Cratogenites corradiniae Martins-Neto, 1996, providing new and more accurate information about the species and confirming its junior synonymy to Protoligoneuria limai Demoulin, 1955. Our results indicate that the diversity of Crato Formation mayflies, both at species and family level, is greater than previously thought, confirming the predominance of hexagenitids among Cretaceous ephemeropterans.