The Yucatán mouse opossum (Tlacuatzin gaumeri) in Quintana Roo, México

The Yucatán mouse opossum (Tlacuatzin gaumeri) is a little-known species so far reported only from the Mexican states of Campeche and Yucatán in the Yucatán Península. Due to the geographic proximity of these states to the state of Quintana Roo and their similar climate and vegetation, the presence of this marsupial in Quintana Roo would be expected. Scientific literature, curatorial records of scientific collections in México, in the GBIF, and observations of the citizen science portal iNaturalistMX were consulted. The curatorial records and one field observation were ordered in a table and a map was elaborated with QGIS 3.36.2. Curatorial records of the scientific collection of T. gaumeri were found in the Mexican state of Quintana Roo. Similarly, one citizen science observation (research grade) was found for Quintana Roo, near the western portion of the Sian Ka'an Biosphere Reserve. The records extend the known geographic distribution of T. gaumeri 139 km (average) eastward from the Yucatán Península. The data record T. gaumeri for the first time in Quintana Roo and confirm its endemicity in that state; they also extend the known geographic distribution of this marsupial. Although its presence coincides with only one natural protected area, it may contribute to its conservation. It still needs to be determined if it applies to any risk category, but the results contribute to the faunal inventory of the Yucatán Península.