Immature stages and biology of the enigmatic oxyporine rove beetles, with new data on Oxyporus larvae from the Russian Far East (Coleoptera: Staphylinidae)

Abstract: Oxyporinae are a visually attractive and highly specialized mycophagous subfamily of rove beetles (Staphylinidae) with enigmatic origins and a largely unknown evolutionary history. Our knowledge of their immature stages and biology, valuable for solving questions about their phylogeny, is still very fragmentary. Here, we describe for the first time the larval morphology of Oxyporus (s. str.) procerus Kraatz, 1879 and O. (Pseudoxyporus) melanocephalus Kirschenblatt, 1938, both from the Russian Far East. We redescribe the larval morphology of the widespread O. (s. str.) maxillosus Fabricius, 1775 based on material, also from the Russian Far East. All larvae are identified based on the combined evidence from rearing and cox1 barcoding. For O. maxillosus, O. procerus and O. (P.) melanocephalus we provide some new field and laboratory-based data on feeding, mating, oviposition, female brood care, duration of larval development, and behavior. We applied the Atheta-based system of Ashe & Watrous (1984) to describe and compare the chaetotaxy of these Oxyporus larvae. We extract the most essential comparable data for all species of Oxyporus with known larvae from poorly compatible published larval descriptions with dubious homology assessments for their chaetotaxy. In addition, data on fungal hosts and beetle biology is summarized for the genus and provided for each species. New morphological traits are revealed for the Oxyporus larvae. Significant differences in larval morphology, reproduction behavior and cox1 barcoding region between the subgenera Oxyporus s. str. and Pseudoxyporus Nakane & Sawada, 1956 correspond to the morphological distance between their adults and suggest that they may be potentially elevated to genus rank.

Key words: Coleoptera, Staphylinidae, Oxyporinae, immature stages, larval morphology, chaetotaxy, brood care, fungivory, mycophagy, Russian Far East, Palaearctic Region