Taxonomic analysis of the Mexican species of Belonuchus Nordmann of the ephippiatus group (Coleoptera: Staphylinidae)

Abstract

We analyzed 117 specimens from eight Mexican states and 22 localities whose taxonomic identifi cation was doubtful to assign them to Belonuchus ephippiatus or B. erythropterus. The goal of this paper is to analyze the most important characters reported in the literature to separate both species and decide if it is one or two entities. The analysis included the measurement of different parts of the body and the proportions between them, however, it was focused on the total body length, the number of punctures that form each of the two central rows of the pronotum, the aedeagus length and its proportion in relation to the body length, because they are the most important characters indicated in the literature that allow to separate the both species. The results showed that is not possible to distinguish the two species with any of the characters analyzed, combined or alone, so we proposed for the second time in the history of these species, that B. erythropterus is a junior synonym of B. ephippiatus. Aspects of the great morphological variation observed in B. ephippiatus, its geographic distribution and its biology are discussed. Moreover, a new species of the same species group was described and it was distinguished from B. ephippiatus based on morphological characters. Finally, we are providing schemes and photographs that help its recognition.