Revision of subfamily Calonecrinae (Coleoptera: Cucujoidea: Nitidulidae) systematics and natural history of a mysterious group

Calonecrinae represent a unique but small subfamily of Nitidulidae that is endemic to South Asia. Their habitats, the South Asian lowland forests, are under the imminent threat of degradation, posing a risk of rapid extinction for these species in their specific locales. Despite the looming threat to their existence, our understanding of this enigmatic group remains limited. We conducted an examination of museum and newly collected specimens, alongside a review of the literature, which led to the discovery of a new species, Calonecrus mindanaoensis sp. nov., from Mindanao, Philippines. Additionally, we provide detailed illustrations of various type specimens of the genus Calonecrus Thomson. For the first time, the immature stages of Calonecrinae were described based on Calonecrus jendeki, with detailed photographs including scanning electron microscopy images. Additionally, their natural history was uncovered, revealing that all life stages are uniquely adapted to complete their entire life cycle in sticky sap. We reevaluate the phylogenetic placement of the Calonecrinae based on phylogenetic analyses of mitochondrial genomes. Calonecrinae positioned within the Epuraeinae clade and are phylogenetically related to the epuraeine genus Trimenus. Consequently, this study proposes reclassifying Calonecrinae as Calonecrini stat. nov., an extremely modified tribe within the Epuraeinae. This research significantly broadens our understanding of the ecology of Calonecrini. Along with the taxonomic and phylogenetic results, we provide a solid foundation for the conservation of this group and further research into their unique habitat preferences and evolutionary behaviour.