The oldest known fossil imago of Ameletopsidae (Ephemeroptera) from 99-million-year-old Kachin amber

Abstract: A new fossil genus and species of the mayfly family Ameletopsidae, Paprika atsukochibae gen. & sp. nov., is described from mid-Cretaceous Kachin amber of northern Myanmar. The specimen represents a female imago and constitutes the oldest known imaginal fossil of the family. Paprika gen. nov. exhibits a unique combination of the characters in wing venation that distinguish it from both extant and extinct Ameletopsidae. Although the new genus is assigned to Ameletopsidae based on imaginal morphological characters, it cannot be placed within the existing subfamilies due to the absence of male or caudal appendage characters. This discovery represents the oldest imaginal Ameletopsidae fossil discovered so far and provides the first fossil record of the family in Asia. The finding supports a broader, possibly Pangean, distribution and origin of Ameletopsidae during the Mesozoic and contributes to the understanding of the evolutionary history and paleobiogeography of Siphlonuroidea. Moreover, the presence of such a lineage in mid-Cretaceous Myanmar suggests greater ecological and geographical diversity within this mayfly assemblages than previously recognized.

Key words: phemeroptera, Siphlonuroidea, Ameletopsidae, Burmese amber, Cretaceous, mayfly, morphology, taxonomy