A New Species of Bryaxis (Coleoptera: Staphylinidae: Pselaphinae) from Mount Etna (Sicily, Italy) and Notes on Its Ecology and Distribution

SIMPLE SUMMARY: A new species, Bryaxis aetnensis sp. nov., has been found on Mount Etna in Sicily, Italy. The species is closely related to the Bryaxis difficilis group, a set of similar beetles found in Sicily and Sardinia. The study describes the unique features and distribution of the Sicilian beetles in this group. Bryaxis aetnensis resembles another species, B. marinae, but can be distinguished by its darker color, longer antennal scape and terminal palpomere, and distinct reproductive organ structure. Bryaxis aetnensis has been discovered at various altitudes on Mount Etna, indicating its adaptability to different environments. This adaptability might explain the observed morphological variability among individuals from different sampling locations. This discovery emphasizes the importance of further exploration on Mount Etna, and why protecting these newly explored areas is crucial. As Mount Etna is relatively young in terms of its volcanic activity, studying the recent colonization of species in this environment provides valuable insights. ABSTRACT: A new species of the subfamily Pselaphinae (Coleoptera: Staphylinidae) has been discovered on Mount Etna (Sicily, Italy) and is described herein as Bryaxis aetnensis sp. nov. The new species is closely associated with the Bryaxis difficilis group, a highly homogeneous group of species living in the regions of Sicily and Sardinia. Diagnostic features and distribution of Sicilian species of this group are treated and illustrated herein. Bryaxis aetnensis sp. nov. exhibits similarities to B. marinae but can be distinguished by the darker color, longer antennal scape and terminal palpomere, and in the aedeagus morphology. The distribution of B. aetnensis sp. nov. spans a wide altitudinal range, demonstrating a remarkable climatic tolerance across the slopes and diverse habitats of Mount Etna. This broad tolerance reflects the species’ probable high ecological plasticity, which may also contribute to the observed morphological variability among individuals from different sampling sites. The significance of this new discovery on Mount Etna highlights the need to intensify sampling efforts in the region. Strengthening protection for these unexplored environments is crucial, and it also aids in unraveling biogeographic questions about the fauna inhabiting the area. As a relatively young volcanic environment, species colonization has occurred recently, making it an intriguing subject of investigation.