The enigmatic terrestrial water scavenger beetle (Hydrophilidae: Sphaeridiinae: Coelostomatini) of the genus Kruia Spangler & Perkins, 1981 was known by a single specimen from Liberia. We rediscovered it at two forested localities in Cameroon (Mt. Cameroon and Mt. Kupe, both of volcanic origin). Adults and larvae of a new species were collected by sifting forest leaf litter. To reveal the phylogenetic position of Kruia, we analyzed a dataset comprising 32 species (incl. 29 of the Coelostomatini) and seven DNA fragments. We recovered three strongly supported monophyla (Dactylosternum, Coelostoma and the Neotropical clade of Coelostomatini genera), with Kruia nested within Dactylosternum Wollaston, 1854, as sister of D. abdominale (Fabricius 1792). Despite of striking differences, Kruia adults share a unique reduction in the number of antennomeres from nine to eight with some species of the D. abdominale group. We, therefore, consider the genus-group name Kruia a junior synonym of Dactylosternum . We describe the Cameroonian species as Dactylosternum riberai sp. nov. and compare it with its sister Dactylosternum chrysopelma (Spangler & Perkins 1981), comb. nov. Mature larvae of the new species identified using DNA sequences are described and compared to other Dactylosternum larvae.

Biology, Cameroon, Coelostomatini, larval morphology, Liberia, molecular systematics, new species