A revision of the endemic south-western African dung beetle subgenus Scarabaeus (Pachysoma) MacLeay, including notes on other flightless Scarabaeini (Scarabaeidae: Scarabaeinae)

The subgenus Scarabaeus (Pachysoma) MacLeay, 1821, is revised. All 13 species of the subgenus are endemic to the west coast of southern Africa. A key to all S. (Pachysoma) species is provided, and their distributions are mapped. Two new species Scarabaeus (Pachysoma) endroedyi and Scarabaeus (Pachysoma) glentoni from the south-western Cape are described. The subspecies S. (P.) denticollis penrithae (Zunino) is synonymized with S. (P.) denticollis denticollis (Péringuey). The synonymy of S. (P.) hessei (Ferreira) with S. (P.) hippocrates (MacLeay) is confirmed. Scarabaeus (Pachysoma) valeflorae (Ferreira), previously considered a synonym of S. (P.) schinzi (Fairmaire), is reinstated as a valid species. The missing type series of Pachysoma hessei Ferreira is traced. A lectotype is designated for Scarabaeus aesculapius Olivier, three paralectotypes are designated for Pachysoma marginatus Péringuey and one paralectotype for Pachysoma denticolle Péringuey. Notes on the type series, distribution records, morphological variation and known biology, are provided for all flightless Scarabaeini. A checklist of all valid species and their synonyms of Pachysoma, Neopachysoma, Mnematium and Neomnematium is included.