Morphology of Guard Hairs in Amazonian Marsupials: Intergeneric Variation, Habitat and Habit Association in a Phylogenetic Framework of the Order Didelphimorphia

The cuticle and medulla of guard hairs exhibit distinct morphological patterns among mammalian species. To investigate this variability in marsupials from the Brazilian Amazon, we analysed guard hairs from nine Didelphimorphia species and incorporated data from an additional 25 didelphid species. We examined how these patterns relate to habitats and habits and proposed phenotypic evolutionary hypotheses within Didelphimorphia. Furthermore, we provide the first descriptions for Philander pebas , P. canus and Didelphis imperfecta . No intraspecific variation was found in cuticle morphology or its relationship with habitats. However, conoidal and lozenge cuticular patterns may be associated with arboreal and terrestrial habits, respectively. While the microstructure of guard hairs is useful for genus‐level identification of mammals, species‐level identification in the diverse Amazonian marsupials remains challenging due to pattern repetition and the reliance on more subjective characteristics.