Unexpected Encounter: A New Genus of Orthosiini (Noctuidae: Hadeninae) Revealed by Tit Predation in Late-Winter Baihuashan National Nature Reserve, Beijing

During a late-winter field survey in Baihuashan National Nature Reserve, Beijing, several noctuid moths were observed flying during the daytime at low temperatures and being actively preyed upon by Marsh tits, which removed the heads and wings of captured individuals. These observations indicate that adults of this noctuid lineage are active in late winter, providing a critical nutritional resource for insectivorous birds during the ecologically constrained, food-limited winter period. Here, we formally describe this lineage as a new genus, <i>Shoudus</i> gen. nov., based on a new species, <i>S. baihuashanus</i> sp. nov., collected from Baihuashan reserve, including three specimens retrieved during active interception of tit predation, along with detached wings and heads recovered from the snow. The new genus is placed in the tribe Orthosiini Guenée, 1837, primarily based on adult external morphology, including large compound eyes with long interfacetal hairs and bipectinate male antennae, as well as forewing patterning similar to certain orthosiine genera such as <i>Perigrapha</i> and <i>Clavipalpula</i>. Notably, the dark reddish-brown forewings with sharply contrasting pale markings, as seen in the new genus and these related genera, appear well adapted for camouflage against bark, leaf litter, and exposed soil in their habitats-potentially functioning as both background matching and disruptive coloration. To further assess its phylogenetic placement, we conducted a molecular analysis based on mitochondrial COI sequences (13 newly generated and 6 retrieved from BOLD/NCBI). The resulting maximum likelihood and Bayesian trees consistently support the monophyly of the new genus and reveal a close phylogenetic relationship with <i>Orthosia</i>, the type genus of Orthosiini. This integrative evidence strongly supports the recognition of <i>Shoudus</i> as a distinct lineage within Orthosiini.