Phylogenetic analysis and taxonomic revision of the termitophilous rove beetle genus <i>Xenogaster</i> Wasmann, 1891 (Staphylinidae: Aleocharinae: Corotocini)

Abstract Xenogaster is a Neotropical genus of rove beetles (Staphylinidae: Aleocharinae) associated with Nasutitermitinae termites (Isoptera: Termitidae). The genus currently comprises 12 described species [Xenogaster inflata Wasmann, 1891, Xenogaster fossulata Mann, 1923, Xenogaster inquilina Borgmeier, 1949, Xenogaster glabriventris Seevers, 1957, Xenogaster nana Seevers, 1957, Xenogaster pilosula Seevers, 1957, Xenogaster reichenspergeri Seevers, 1957, Xenogaster subnuda Seevers, 1957, Xenogaster mexicana Kistner &amp; Jacobson, 1976, Xenogaster pseudonuda Pires-Silva, 2023, Xenogaster kymopoleia Pires-Silva, 2023, and Xenogaster lugens Pires-Silva &amp; Zilberman, 2023], and despite the diversity, its biology and interspecific relationships remain poorly understood. In this study, we conducted a taxonomic revision and phylogenetic analysis of the genus. Our dataset comprising 158 morphological characters and 28 taxa was analysed under maximum parsimony, maximum likelihood, and Bayesian inference. All analyses recovered Xenogaster as a non-monophyletic group, and based on the results, we describe a new genus, Neotermitosyne Moreno gen. nov., to accommodate X. fossulata, resulting in the proposal of the new combination Neotermitosyne fossulata comb. nov. Furthermore, based on the results, we transfer X. mexicana to Trachopeplus, proposing Trachopeplus mexicanus comb. nov. While examining material housed at the Museu de Zoologia da Universidade de São Paulo (MZSP), we identified a new species, Xenogaster rochai Moreno sp. nov., which is described herein. Updated taxonomic keys to Xenogaster and the Neotropical genera of Termitogastrina are provided, along with new termite host records, new state records for Southeastern Brazil, and an updated distribution map.