Zhoucloeon Gen. Nov., (ephemeroptera, Baetidae), a New Mayfly from the Mid-Cretaceous Kachin Amber

Baetidae is one of the most diverse family within Ephemeroptera, yet its related fossil record remains sparse and fragmentary. Cretaceous fossil and amber mines have yielded several enigmatic baetid-like fossils, some previously assigned to Baetidae or its extinct subfamily Palaeocloeoninae. Here, we describe a new genus and species of Palaeocloeoninae, Zhoucloeon changfai gen. et sp. nov., based on a wellpreserved male imago from mid-Cretaceous Kachin amber and demonstrate that it does not conform to the diagnosis of any known baetid genera. Comparative morphological analysis especially of wing venation and male genital structures was made between the new mayfly and related taxa. The discovery of Zhoucloeon changfai gen. et sp. nov underscores the underestimated diversity of early baetids and provides new insights into the morphological disparity of Baetidae during the Cretaceous.