Boundaries

This interior ecoregion lies in central Mexico, primarily in San Luis Potosí, as well as Zacatecas, Nuevo León, Tamaulipas, and Guanajuato.

Topography

Llanos el Salado lies on the Mexican Plateau and is mostly flat to hilly, with few mountains except along the ecoregion boundary. Elevations range from 400 to over 3400 m, grading down toward the Rio Grande/Río Bravo in the northeast and the Río Pánuco in the southeast. There is less drainage toward the Río Lerma in the southwest.

Freshwater habitats

There are primarily isolated springs, with no permanent runs. The basins are mostly arheic, with no signs of surface flows.

Terrestrial habitats

The terrestrial habitats are primarily comprised of dry scrub of the Meseta Central matorral and Central Mexican matorral, with pockets of Sierra Madre Oriental pine-oak forests.

Description of endemic fishes

The harshness of the habitats, the tectonism of the rock upon which these basins often sit, and the relative genetic isolation of the aquatic species of the basins has lead to the development of a highly specialized and unique fauna. The Llanos el Salado’s species richness is fairly low, but its endemism is high. Seventy-five percent of the fish species that are found in the area are endemic. These are restricted to members of theCyprinodontidae family, and include the Potosi pupfish (Cyprinodon alvarezi), Villa Lopez pupfish (C. ceciliae), Charco Azul pupfish (C. inmemoriam), La Palma pupfish (C. longidorsalis), Charco Palma pupfish (C. veronicae), and Catarina pupfish.

Justification for delineation

Ecoregion delineations were based on qualitative similarity/dissimilarity assessments of major basins, using the standard administrative hydrographical regions of the Mexican federal government. This ecoregion has high endemism in a highly fragmented environment, composed mainly of small springs or groups of springs.

Level of taxonomic exploration

Good