Boundaries

Largely defined by the watersheds of the Río Sabinas and Río Salado, this ecoregion includes central and eastern Coahuila, northern Nuevo León, and a small portion of Tamaulipas.

Topography

The Río Salado originates in low mountains of the Sierra Madre Oriental, and flows in a southeasterly direction through plains.

Freshwater habitats

The ecoregion is characterized by clear headwater streams, mostly piedmont, and slow plains in the middle to lower reaches. This basin has two ecologically very distinctive tributaries: the Northern Río San Juan, with strictly freshwater, hilly headwaters and hard bottoms; and the Southern Río Salado de Nadadores along the plains, which is highly saline for the most part. The mainstem of the Río Salado has high salt content, is muddy, and is low gradient. 

Terrestrial habitats

The ecoregion is characterized by the Chihuahua desert in the west, with pockets of Sierra Madre Oriental pine-oak forests. Tamaulipan mezquital is the dominant vegetation type in the east, with small areas of Tamaulipan matorral. Mesquite-grassland is characteristic within Tamaulipan mezquital. Creosote bush (Larrea tridentata) is dominant in the Chihuahuan Desert (World Wildlife Fund 2001).

Description of endemic fishes

Several near-endemic species characterize each section of the ecoregion: Devils River minnow (Dionda diaboli), spotted minnow (D. melanops), and Mexican red shiner (Cyprinella rutila) in the San Juan, Río Salado darter (Etheostoma segrex) in the Salado de Nadadores, Salado shiner (Notropis saladonis) in the Río Salado, and Mexican blindcat (Prietella phreatophila)in subterranean waters. The Salado shiner is the only species considered to be a strict endemic to the ecoregion.

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.