Phloeosinus deleoni Blackman, 1942 (Coleoptera, Curculionidae, Scolytinae) is a bark beetle for which limited information exists regarding its ecology, distribution and host range. The objective of this study was to delimit its current distribution, identify confirmed host plants, explore possible additional hosts and model its potential distribution, based on the availability of known hosts. Records from scientific collections and field sampling were used to define its current distribution and Maxent in RStudio was applied to generate potential distribution models. New records were obtained in Durango, although the general distribution pattern remained congruent with previous knowledge. Juniperus flaccida and Juniperus deppeana were confirmed as primary hosts, with direct feeding observed on J. deppeana, expanding its known host range. While associations with other Juniperus species were considered, available data and distribution maps did not support this hypothesis. Environmental variables, particularly the temperature of the warmest month and annual precipitation, accounted for a substantial portion of the variation in ecological suitability. However, the presence of climatically suitable areas lacking records of occurrence indicates potential regions for colonisation. The absence of records in these areas is likely related to host ecology, as well as biological, dispersal and geographical constraints of P. deleoni. Potential distribution models indicated high environmental suitability in the biogeographic provinces of the Sierra Madre del Sur, Sierra Madre Oriental and the Transmexican Volcanic Belt. Overall, the results reinforce the hypothesis that P. deleoni is an oligophagous beetle, closely related to Juniperus species, with a host-use bias towards J. flaccida and is considered a native species restricted mainly to the central region of the Mexican Transition Zone.
