A new species of Tequila Giant Skipper Aegiale C. Felder & R. Felder, 1860 (Lepidoptera, Hesperiidae, Megathymina) from Sonora, Mexico

Aegiale C. Felder & R. Felder, 1860 has traditionally been treated as a monotypic genus of Giant Skippers (Hesperiidae: Megathymina), represented by A. hesperiaris (Walker, 1856), which occurs from northern to central Mexico, mostly east of the Sierra Madre Occidental mountain range. Here, we describe a second species, Aegiale occidentalis KC, McGuire & Shirey, sp. nov., from Sonora, Mexico, occurring in the Sierra Madre Occidental.

Morphological comparisons, including female genitalia, were used to diagnose the new species. Aegiale occidentalis sp. nov. differs from A. hesperiaris in dorsal forewing coloration, with fully orange apical and discal cell spots, and in female genitalia, including shorter papillae anales and a reduced sterigma. We provide illustrations of the habitus and female genitalia of both species, a key to differentiate them, and a key to distinguish Aegiale from other Megathymina genera.

The discovery of A. occidentalis sp. nov. expands the known diversity of the genus and highlights underexplored montane regions in northwestern Mexico, with implications for the biogeography of agave-feeding Megathymina.