Frolov, A. V. & Akhmetova, L. A. 2015. Rediscovery of the enigmatic Stenosternus costatus Karsch (Coleoptera: Scarabaeidae: Orphninae) from São Tomé island. Zootaxa, 4007, 440–444.
Stenosternus Karsch, 1881 is one of the least-known genera of the Orphninae scarab beetles. It was described from a single specimen of the odd-looking S. costatus Karsch, 1881, from the island of São Tomé, Gulf of Guinea, West Africa. Since then, no more findings of S. costatus have been reported... We discovered additional specimens of both sexes of S. costatus housed in the Museo Civico di Genova, Genova, Italy (MCGI) and California Academy of Sciences, San Francisco, California, United States of America (CASC). In this note we describe a female of S. costatus and discuss the species distribution and the taxonomic position of the genus.