First record of the white-eared cotton rat (Sigmodon leucotis) for the state of Tlaxcala, Mexico

Abstract

The white-eared cotton rat (Sigmodon leucotis) is a rodent endemic to Mexico, typically inhabiting montane forests and grasslands throughout the Trans-Mexican Volcanic Belt and major mountain ranges. The species typically inhabits pine, pine-oak, cloud forests, and mountain grasslands or meadows. Despite its presence in neighboring states, formal records for Tlaxcala were previously absent. We monitored terrestrial fauna within a solar park in San Antonio Techalote, Hueyotlipan, Tlaxcala, Mexico. We conducted systematic daily surveys between solar panels year-round, utilizing hand-capture techniques. We report the first records of S. leucotis in the state. Three male individuals were captured during surveys conducted in March and April 2026 within grasslands adjacent to agricultural areas. Somatic measurements of one specimen (total length: 215 mm; tail: 85 mm; hind foot: 31 mm; ear: 21 mm) and external diagnostic features, the whitish inner ear surface and tail scale width, confirm the identification. This finding expands the known geographical distribution of the species and contributes to the mammalian checklist of Tlaxcala. Furthermore, this record highlights the importance of environmental monitoring programs associated with renewable energy projects as valuable and complementary sources of biological information for regional biodiversity management.