Ecoregion Description

170: Sierra Madre del Sur

Major Habitat Type:

tropical and subtropical coastal rivers

Author:

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

Countries:

Mexico

Boundaries:

This ecoregion stretches along the coast from Guerrero south through most of Oaxaca to, but not including, the Tehuantepec basin. It encompasses numerous rivers on the southern slopes of the Continental Divide that drain into the Pacific Ocean.

Drainages flowing into:

Pacific Ocean

Main rivers or other water bodies:

Among the major rivers in this ecoregion are the Petatlán, Papagayo, Verde, and Colotepec.

Topography:

The ecoregion covers the rugged Sierra del Sur, a mountain range with peaks reaching 3500 m asl. It includes a short piedmont and almost no coastal plain.

Climate:

This ecoregion has a tropical wet and dry climate. This climate zone has a distinct dry season, with the driest month averaging less than 60 mm. In addition, monthly mean temperature is usually above 18 ºC.

Freshwater habitats:

Freshwater habitats are primarily a non-distinctive set of minor basins along short coastal plains. However, the Río Verde flows mostly over high plateau.

Terrestrial Habitats:

Terrestrial habitats include Southern Pacific dry forests along the coast and pine-oak forests at higher elevations.

Fish Fauna:

Only Notropis imeldae is considered a strict endemic to the ecoregion. Near-endemics include the three spot cichlid and Poeciliopsis turrubarensis.

Other noteworthy aquatic biotic elements:

This ecoregion harbors the highest levels of richness and endemism of aquatic herpetofauna in North America. Among the endemics are the Sierra Madre del Sur frog (Rana sierramadrensis) and Guerrero leopard frog (Rana omiltemana).

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 comprised of very small coastal basins, flowing from high mountains, with endemics only in the largest basin, Río Verde.

Level of taxonomic exploration:

The level of taxonomic exploration is poor in general due to the highly mountainous terrain and few roads.

References/sources:

Abell, R. A., Olson, D. M., et al. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.

Alvarez del Villar, J. (1972). "Ictiología Michoacana V. Orìgen y distribución de la ictiofauna dulceacuìcola de Michoacán" Anales de la Escuela Nacional de Ciencias Biologicas Mexico 19 155-161.

Alvarez del Villar, J. (1970). "Claves de Peces Mexicanos (Claves)" México: Dirección General de Pesca e Industrias Anexas.

Doadrio, I., Carmona, J. A., et al. (1999). "Genetic variation and taxonomic análisis of the subgenus Profundulus" J. Fish Biol. 55 751-766.