Review of Madrasostes Paulian, 1975 (Coleoptera: Hybosoridae: Ceratocanthinae) from Vietnam, with remarks on its generic limits

A review of the genus Madrasostes Paulian, 1975 (Coleoptera: Scarabaeoidea: Hybosoridae: Ceratocanthinae) in Vietnam is provided. A total of four species are treated: Madrasostes tonkinense (Paulian, 1945), M. deharvengi Gao, 2009, M. bartolozzii Ballerio, 2013, and M. nomurai Ballerio & Maruyama sp. nov. from Ninh Binh Province. New locality records are presented for M. tonkinense and M. deharvengi is recorded from Vietnam for the first time. The male of M. bartolozzii is described for the first time based on recently collected material. An identification key to the Vietnamese species of Madrasostes is also provided. Our findings contribute to a clearer understanding of the diversity and distribution of flightless Ceratocanthinae in Indochina and raise questions about the morphological limits of the genus. Additionally, M. tonkinense is newly recorded from Laos and Thailand.