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# of Endemic Species
Major Habitat Type:
tropical and subtropical coastal rivers
Salvador Contreras Balderas, Universidad Autónoma de Nuevo León. Additional text was modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment
Allison Pease, Texas A&M University, Dept. of Wildlife & Fisheries Sciences
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.
Drainages flowing into:
The drainages of this ecoregion flow into the Gulf of Mexico.
Main rivers or other water bodies:
The main rivers in the ecoregion include the Río Pánuco, Río Tamesí, Río Soto la Marina, and Río Verde/La Media. Some southern headwaters of the Río Pánuco were formerly part of the Lerma basin.
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.
The eastern portion of the ecoregion is humid and tropical, with average annual rainfall ranging from 1100 to 1600 mm. Along the northeastern slopes of the Sierra Madre Oriental, the climate tends to be temperate humid.
Freshwater habitats of the ecoregion include springs, creeks, coastal plain rivers, and coastal freshwater and brackish lagoons.
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.
The ecoregion is dominated by a number of primary (Cyprinidae and Ictaluridae) and secondary (Poeciliidae, Cichlidae, Goodidae) families. Genera with the most abundant number of species include Xiphophorus, Herichthys, Dionda, Gambusia, and Poecilia.
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).
Several genera, including Dionda, Xiphophorus, and possibly in some Gambusia, exhibit speciation within closely related and presumably monophyletic lineages. Prietella lundbergi is a troglobiotic species. One sub-basin of particular importance is the Rìo Verde/La Media Luna basin, which begins with several springs, the biggest of which is the Media Luna. These flow into the Río Verde in the most upstream headwaters of the Río Pánuco. The thermal environments of the springs and the topographic isolation of this region have led to the evolution of two endemic genera, Ataeniobius and Cualac, and to the diversification of a few members of the complex of species of Dionda.
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:
Abell, R. A., Olson, D. M., et al. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.
Artigas Azas, J. M. (1993)"Herichthys tamasopoensis n. sp., a new cichlid from Mexico (Pisces, Cichlidae)" In Konigs, A.A. (Ed.). The Cichlids Yearbook 3. (pp. 65 - 70) Germany: Cichlid Press.
Contreras-Balderas, S.,Lozano-Vilano, M. L. (1994). "Cyprinella alvarezdelvillari, a new cyprinid fish from Río Nazas of México, with a key to the lepida clade" Copeia 1994(4) 897-906.
Darnell, R. M. (1962). "Fishes of the Rio Tamesí and related coastal lagoons in East-central México" Publications of the Institute of Marine Science 8 299-365.
Hubbs, C. L.,Miller, R. R. (1977). "Six distinctive cyprinid fish species referred to Dionda inhabiting segments of the Tampico Embayment drainage of Mexico" Trans. San Diego Soc. Nat. Hist. 18(17) 267-336.
Miller, R. R. (1956). "A new genus and species of cyprinodontid fish from San Luis Potosi, Mexico, with remarks on the subfamily Cyprinodontinae" Occ. Pap. Mus. Zool. Univ. MI 581(1 - 17)
Obregón-Barbosa, H., Contreras-Balderas, S., et al. (1994). "The fishes of Northern and Central Veracruz, México" Hydrobiologia (Belgium) 286 79-95.