Abstract The identification of biodiversity conservation priority sectors that are not formally protected, have an essential part of conservation strategies and goals at global and local scale. Ecological niche modeling is a relevant and important tool for analysis and distribution of species, also is used to determine the biodiversity patterns through the regions. The main objective of this work was to identify the sites with high biodiversity patterns in a sector of Chaco Seco ecoregion that haven’t been protected with environmental legislation. Through biodiversity sampling with foot transects, camera traps and interviews, it was registered the presence of large and medium mammals in Santiago del Estero Province. Biodiversity pattern maps were then developed from potential distribution models (SDMs) of 5 mammalian species selected for being relevant for conservation. To define zones that could be characterized like conservation gaps, pattern maps were contrasted with protected areas layers and legal schemes of land use planning and also, protected forest. For the SDM, 171 records were used, 43 for M. gouazoubira, 40 for P. concolor, 20 for M. trydactila, 43 on P. tajacu and 25 on C. wagneri. Three models were used to make the biodiversity patterns, one of these, Fuzzy union, were used for the subsequent calculation. The total area of high biodiversity increases to 39.486 km², which represents the 29% of provincial area. In consequence the 81% remaining represents the conservation gaps areas for that sector of the ecoregion.