Taxonomic revision and notes on natural history of the enigmatic: beetle genus Gibboryctes Endrodi (Coleoptera: Melolonthidae: Dynastinae)

The enigmatic beetle genus Gibboryctes Endrodi, 1974 (Melolonthidae: Dynastinae: Oryctini) is revised and redefined herein. The type species Gibboryctes szelenyii Endrodi, 1974 is redescribed, and Gibboryctes ebeninus sp. nov. and Gibboryctes endroedii sp. nov. are proposed. Gibboryctes gracilicornis (Prell, 1912) has its original combination (Heterogomphus gracilicornis Prell, 1912) revalidated. Gibboryctes waldenfelsi (Endrodi, 1977) and Gibboryctes impunctatus Dupuis, 2019 are placed in Tetragus gen. nov. Notes on the natural history of Gibboryctes are presented on specimens that were collected inside epigeous termite nests and from a Eucalyptus crop. Illustrations and known distribution maps are provided for all studied species. Diagnoses are presented separately for both Gibboryctes and Tetragus species. Furthermore, identification keys to the Gibboryctes species and South American genera of Oryctini are provided.