Revised classification and phylogeny of an Afrotropical species group based on molecular and morphological data, with the description of a new genus (Coleoptera: Scarabaeidae: Onthophagini)

Abstract

The worldwide distributed Onthophagus genus comprises at present more than 2000 species, that often show a complicated and uncertain systematic history. In particular, the many Afrotropical species included in this genus have never been entirely reviewed after the division into 32 species groups proposed by d’Orbigny in 1913, although subsequent researches focusing on some of these species suggested that Onthophagus constituted a nonmonophyletic taxon. In order to highlight their phylogenetic relationships, the various Afrotropical species groups of d’Orbigny must thus be examined, and it would be advisable to study them separately to avoid misunderstanding. In this framework, the taxonomic position of the three species currently included in the 21st d’Orbigny group was examined. Both morphological and biomolecular analyses contributed in confirming that these species (i.e., Onthophagus caffrarius d’Orbigny, 1902; Onthophagus quadraticeps Harold, 1867; and Onthophagus signatus Fahraeus, 1857) constituted a well-defined monophyletic group that cannot be maintained within the genus Onthophagus. Therefore, the Kurtops gen.n. is here described to accommodate these Afrotropical species, that are nevertheless always included within the Onthophagini tribe. On the basis of the phylogenetic relationships here elucidated, it was also emphasized that the new genus is strictly related to Digitonthophagus and Phalops; thus, it was proposed to include the three genera into a single clade of suprageneric rank naming it as Phalops complex.