The semi-arid zone of Querétaro and Hidalgo, in Central Mexico, is an important region for cactus conservation. Mammillaria herrerae Werderm. is a species of local distribution with a threatened conservation status, partly because it has been historically plundered. An exhaustive census of all individuals was made to assess the current status of the species. As a result of the study, a new site is included, which increases the distributional range, and we found that M. herrerae faces adverse factors for its survival, namely: a very small number of wild individuals fragmented into small scattered groups; an extremely reduced area of distribution, and a very specific set of habitat requirements. A clear association of the species with its vegetative and rocky nurses was observed. These characteristics confirm the vulnerability of M. herrerae and suggest its dependence on a specific environment and ultimately the need for protection in its areas of distribution.