We report the first confirmed occurrence of the Guianan White-eared Opposum Didelphis imperfecta Mondolfi & Pérez-Hernéndez, 1984 (Didelphimorphia: Didelphidae) from Colombia. The individual was captured in a tropical lowland rain forest in the easternmost portion of the Colombian Orinoco Llanos region. The species is endemic of the Guiana Shield and has the smallest distribution area among the species of the genus. Our record shows that the Orinoco river does not constitute a biogeographical barrier for the species. To date, only two species of the genus Didelphis Linnaeus, 1758 have been recorded in Colombia, our results increase the reported number of records for this genus.

The high plains native savanna landscape (HPNSL) northeast of the Orinoco River is the habitat of 50% of the wild ungulate species (WUS) reported for Colombia. Over the last 20 years, this high species diversity has been strongly threatened by the accelerated human transformation of the natural land cover causing connectivity loss of the habitats. Despite this situation, the region lacks a biological connectivity analysis with a multi-species approach involving species groups that are representative of the savanna ecosystem such as the WUS. Understanding the spatial distributions of suitable habitats and the main habitats that act as primary habitats for ungulate focal species (UFS) in these landscapes is fundamental for the design of effective conservation strategies. Here, we use an occurrence dataset for Tapirus terrestris, Odocoileus virginianus, and Tayassu pecari in the development of species' potential distribution models, the binarization process, and morphological spatial pattern analysis. This information was used for the modelling of dispersal corridors connecting the core habitats of the UFS using the randomized shortest path algorithm and quantifying the weighted global connectivity metrics. Our results suggest an integral corridor with potential least-cost dispersal routes between the HPNSL on the middle and lower-middle basins of the savanna rivers and, to a lesser extent, the lower basin of the Meta River. These areas associated with the fluvial dendritic systems are connected, while the core habitats in the eastern part of the savanna landscape are largely disconnected. We discuss how the application of such knowledge on the spatial ecology of ungulate species might improve management of the metapopulations in the Colombian HPNSL.