Diversity, distribution, and conservation of the Cactaceae (Caryophyllales) from Tamaulipas, Mexico

Abstract

Geographical distribution, diversity, endemism, and conservation of Cactaceae in the Mexican state of Tamaulipas were analyzed based on distributional data obtained from specialized literature, fieldwork, and herbarium specimens. Tamaulipas territory was divided into grid-cells of 10 × 10 minutes latitude/longitude and was used as units of analysis. Cactaceae comprises 174 taxa and 33 genera in Tamaulipas, representing a high proportion of the Mexican cacti with 65% at the generic level and 23% at the specific level. The richest genera are Opuntia (40), Mammillaria (35), Echinocereus (16), and Turbinicarpus (14). Thirty one Cactaceae taxa are new records for the state. The highest diversity of species occurs in the southwestern region associated with the Sierra Madre Oriental slopes and the Jaumave Valley. Cacti are well represented in the state Natural Protected Areas of Tamaulipas compared to the federal conservation areas. We conclude that Tamaulipas constitutes a nodal area because it is located at the boundaries among four different biogeographic regions representing zones of biotic overlap promoted by historical and ecological changes allowing the mixture of different biotic elements and in situ speciation. For this, it is considered one of the richest Mexican states in terms of Cactaceae diversity.