Background:

The xeric scrublands of Mexico have been studied floristic and ecologically, but few studies include the panbiogeographic method to describe their species distribution patterns.

Hypotheses:

The Mexican Xerophytic Region contains a high richness of endemic species of Mexico restricted to the xeric scrubland’s biome, most of them typical of this region. Based on these species a regionalization of the arid zones of Mexico can be proposed.

Study site:

Mexican Xerophytic Region.

Methods:

A panbiogeographic study was carried out based on a parsimony analysis of endemism and progressive elimination of characters from 21 Mexican areas with xeric scrublands, including a locality in northwest of Metztitlán, Hidalgo, with a recent floristic inventory. The data matrix contains 248 species of vascular plants endemic to Mexico, distributed mainly in the xeric scrubland biome.

Results:

Eleven generalized tracks located in the floristic provinces of Baja California, Sonora, Northern Plateau, Southern Plateau and Volcanic Belt were identified. Additionally, 13 biogeographic nodes were recorded, most of them in the Southern Plateau. The analyzed endemic species are particular to the xeric scrublands, although some of them are shared with temperate forests.

Conclusions:

Five arid zones of Mexico are recognized: Sonora Desert, Tehuacán-Cuicatlán Valley, Chihuahuan Desert, Guanajuato-Jalisciense arid zone and Queretano-Hidalguense arid zone. The last four areas are likely to have constituted a continuous arid zone, fragmented by recent climatic and orographic events. The nodes obtained allowed us to recognize areas with a high richness of endemism that must be conserved.

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