Stenosternus Karsch, a possible link between Neotropical and Afrotropical Orphninae (Coleoptera, Scarabaeidae)

Andrey Frolov

doi:10.3897/zookeys.335.5471

Abstract

The monotypical orphnine genus Stenosternus Karsch is known from a single specimen of Stenosternus costatus collected on the São Tomé island (Gulf of Guinea). The holotype of Stenosternus costatus Karsch is re-examined and its characters are discussed and illustrated. Although the genus was implicitly placed by Paulian (1984) in the Old World tribe Orphnini Erichson, re-examination of the holotype of Stenosternus costatus shows that it has characters similar to those of the members of the New World tribe Aegidiini Paulian. Placement of Stenosternus in the Aegidiini is supported by the metepisternum widened posteriorly (forming posterior metepisternal lock for closed elytra) and a keel separating basal and anterolateral parts of propleurae. Relationships of Stenosternus with other orphnine taxa and possible ways of origin of São Toméan orphnine fauna are discussed.

Highlights

Orphninae Erichson is a group of predominantly tropical scarab beetles
15 genera and 195 species of Orphninae are known (Frolov 2012) and they are classed into two tribes, Aegidiini Paulian comprising four Neotropical genera and Orphnini Erichson comprising the rest of the genera distributed in the Old World (Paulian 1984)
According to Paulian’s (1984) classification, the genus should be considered in the tribe Orphnini because it originates from the Old World

Summary

Introduction

15 genera and 195 species of Orphninae are known (Frolov 2012) and they are classed into two tribes, Aegidiini Paulian comprising four Neotropical genera and Orphnini Erichson comprising the rest of the genera distributed in the Old World (Paulian 1984). Paulian did not discuss characters of the genus and how they fit diagnoses of the tribes and apparently he never saw the type specimen of S. costatus Karsch, 1881. In his earlier work Paulian (1948) wrote that Stenosternus was unknown to him. Relationships of Stenosternus with other orphnine taxa and possible ways of origin of the São Toméan orphnine fauna are discussed

Material and methods

Findings

Discussion