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

## TL;DR

A new genus of moth, Shoudus, was discovered in Beijing's Baihuashan reserve, active in late winter and preyed upon by birds.

## Contribution

The discovery of a new genus, Shoudus, and its placement within the tribe Orthosiini using morphological and molecular data.

## Key findings

- Shoudus baihuashanus is a new genus and species of moth active in late winter and preyed upon by Marsh Tits.
- Morphological and DNA evidence places Shoudus in the tribe Orthosiini and shows a close relationship with Orthosia.
- The new genus exhibits camouflage adaptations and contributes to bird diets during food-scarce winter periods.

## Abstract

During late-winter surveys in northern China, we observed a previously undocumented moth flying in daytime at low temperatures and being preyed upon by Marsh Tits. Based on these observations and collected material, we describe a new genus and species, Shoudus baihuashanus. Morphological characters and DNA data place this lineage in the tribe Orthosiini Guenée, 1837 and indicate a close relationship with Orthosia. This discovery highlights a poorly known group of moths active in late winter and suggests that such insects may contribute to the winter diet of insectivorous birds.

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, Shoudus gen. nov., based on a new species, S. baihuashanus 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 Perigrapha and Clavipalpula. 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 Orthosia, the type genus of Orthosiini. This integrative evidence strongly supports the recognition of Shoudus as a distinct lineage within Orthosiini.