Coat color in Thylamys karimii (Petter, 1968) (Didelphimorphia, Didelphidae) in northeastern Brazil: intraspecific variation and geographic distribution

ABSTRACTKnowledge of Didelphidae taxonomy and diversity has increased steadily over the last decades, mainly due to increasing collection efforts and revisionary works. Yet, especially for mouse opossums, a proper appraisal of morphological variation is still incipient. Thylamys karimii occurs in the Brazilian biomes of Caatinga and Cerrado, and specimens with two different shades of dorsal coloration (brown and gray) were recently documented in sympatry in the Parque Nacional (PARNA) do Catimbau (Caatinga biome). We used qualitative and morphometric data from skulls and skins (n = 7 from PARNA Catimbau and n = 26 from other localities) to compare these two coat color morphotypes and characterize the morphological diversity and taxonomic status of the Caatinga populations. We used Student’s t-tests to compare sexes and morphotypes’ measurements. We found at least three well-defined coat color morphotypes distinguishable by dorsal and ventral coloration and not restricted to PARNA Catimbau. Variation of the other morphological traits suggests that these morphotypes are more likely a case of intraspecific variation in the Brazilian northeastern region. Morphometric differences, particularly between coat color morphotypes, might be better elucidated in larger samples. Additionally, these specimens represent an important extension of the species’ known distribution reaching the Atlantic Forest borders.KEYWORDS: Opossumsmorphotypescolorationpelage colorCaatinga AcknowledgmentsWe are thankful to Pedro Cordeiro-Estrela (UFPB, João Pessoa, Brazil), and the support staff of the Mammal Collections we visited for their support and infrastructure during the analysis of the vouchers. Ana Paula Carmignotto (UFSCar, Sorocaba, Brazil) and Marcos Brandão (USP, São Paulo, Brazil) made important comments and suggestions when this manuscript was still an undergraduate thesis, and comments from two anonymous reviewers helped us in improving the final text. We also thank the Muséum national d’Histoire naturelle (Paris) for the photo of the holotype.Disclosure statementNo potential conflict of interest was reported by the authors.Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/01650521.2023.2276211Additional informationFundingThis research was supported by grants from CNPq, CAPES, and FACEPE to DA and the UFPE Mammal Collection. MC was supported by a UFPE-CNPq (Iniciação Cientifica) fellowship and a grant from SBMz during the development of this work and is currently supported by a FACEPE MSc. Fellowship (IBPG-0154-2.04/22).