Boundaries

This ecoregion lies along the east coast of Mexico from the Río Soto la Marina basin to the  Río Nautla basin. It is bounded to the west by the Sierra Madre Oriental and to the east by the Gulf of Mexico. It crosses the states of Tamaulipas, San Luis Potosí, Guanajuato, Querétaro, Hidalgo, Mexico, Puebla, and Veracruz.

Topography

The topography of the ecoregion is varied, with mountains, deep canyons and plateaus characterizing the Sierra Madre Oriental in the west to the gentle slopes along the Gulf of México coastal plain. The eastern slopes of the Sierra Madre Oriental are composed of sedimentary rocks from the cretaceous period. Elevations range from sea level to over 3000 m, with the highest peak at nearly 3700 m asl.

Freshwater habitats

Freshwater habitats of the ecoregion include springs, creeks, coastal plain rivers, and coastal freshwater and brackish lagoons.

Terrestrial habitats

The ecoregion is dominated by Veracruz moist forests throughout much of the ecoregion. These are tropical moist broadleaf forests, with characteristic species including Mayan breadnut (Brosimum alicastrum), sapodilla (Manilkara zapota), and rosadillo (Celtis monoica). To the north the moist forests transition to Tamaulipan mezquital and Tamaulipan matorral. Higher elevations in the west are characterized by Sierra Madre Oriental pine-oak forests, and Central Mexican matorral and Meseta Central matorral. Meso-American Gulf Caribbean mangroves line the coast.

Description of endemic fishes

The ecoregion hosts a unique fish fauna, with roughly 60% of the species endemic to the ecoregion. Some endemic species of special interest include the cavefish, Astyanax jordani, and phantom blindcat (Prietella lundbergi), both cave-restricted species. Other species of special note include those restricted to Rìo Verde/La Media Luna. These include the bicolor minnow (Dionda dichroma), flatjaw minnow (Dionda mandibularis), bluetail goodea (Ataeniobius toweri), and checkered pupfish (Cualac tessellatus).

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 is noted for its high endemism in several groups, especially in the cyprinid genus Dionda, and the poeciliid genus Xiphophorus, considered as a few clades of closely related species. The Pánuco basin has long been proposed as a transition between the Nearctic and Neotropical realms.

Level of taxonomic exploration

Reasonably good