Revision of Oxyporinae (Coleoptera: Staphylinidae) of Russian fauna: getting to the bottom of enigmatic fungivorous subfamily's taxonomy and biology

The members of Staphylinidae subfamily Oxyporinae, colorful and relatively big beetles, were always attractive for coleopterists. Currently there are more than 130 species of these obligate fungivores. Their eye-catching habitus, variability of size, within a species, and lack of evident morphological differences led to many taxonomical problems in this group. Many species are described based only on coloration, which leads to the origin of multiple synonymy cases: many species are differently colored singletons. The genus contains subgenera Oxyporus and Pseudoxyporus, sometimes cited as separate genera, which makes the taxonomic turmoil harder to resolve. In his Pseudoxyporus revision, Makranczy stressed the special importance of the morphological variation in the complex endophallus of this genus. We delimited species of Russian fauna, including all European and several Oriental species, based on BI and ML analysis of combined DNA-barcoding and morphological data. We tested groups of morphological characters for the most parsimonious criteria and inferred the Ancestral States Reconstruction to get the evidence for the most and the list reliable traits, including coloration, outer morphology, and structure of endophallus. The revision revealed 10 species of Oxyporus in Russian fauna and established two new synonyms, Oxyporus (Oxyporus) basicornis Cameron, 1930 = O. (O.) aequicollis Bernhauer, 1935, syn. nov. = O. (O.) parvus Lee et al., 2020, syn. nov. Lectotypes are designated for O. (O.) basicornis Cameron, 1930, O. (O.) germanus Sharp, 1889, O. (O.) niger Sharp, 1889, and O. (O.) triangulus Sharp, 1889. Comprehensive taxonomic treatment and an identification key are provided for all species.