Ameca - Manantlan
Salvador Contreras Balderas (Universidad Autónoma de Nuevo León), Jennifer Hales
Major Habitat Type
Tropical and subtropical coastal rivers
Drainages flowing into
Drainages flow into the Pacific Ocean.
Main rivers to other water bodies
There are several minor basins from the Río Ameca in the north to the Río Ahuijallo in the south, with each an independent basin draining into the Pacific Ocean.
This ecoregion encompasses a small part of southern Nayarit, southern Jalisco, northwestern Michoacán, and the entire state of Colima. Its extent is determined by the watersheds of the Río Ameca in the north and the Río Ahuijallo in the south.
The ecoregion is mountainous, and traversed by numerous canyons. Elevations range from sea level to nearly 4000 m.
Freshwater habitats are characterized by coastal or short course rivers, with narrow or non-existent floodplains, especially in the northern areas.
Terrestrial habitats include primarily dry forests and pine-oak forests, with stands of mangroves along the coast.
Description of endemic fishes
The Ameca-Manantlán is distinctive because of its endemism, especially among fish. Over half of its fish are endemic, and it has one endemic species of aquatic herpetofauna. Endemics usually occupy only one of the small basins within the ecoregion, except for Poeciliopsis, which is known to extend throughout the ecoregion in highly saline waters. There are a large number of endemic splitfins (Goodidae), including whitepatched splitfin (Allodontichthys hubbsi), finescale splitfin (A. polylepis), tuxspan splitfin (A. tamazulae), bandfin splitfin (A. zonistius), butterfly splitfin (Ameca splendens), goldbreast splitfin (Ilyodon furcidens), Limones splitfin (Ilyodon xantusi), golden skiffia (Skiffia francesae), leopard splitfin (Xenotaenia resolanae), black splitfin (Xenotoca melanosoma), and Tequila splitfin (Zoogoneticus tequilae). Some endemics in the Poeciliidae family include dwarf molly (Poecilia chica), golden livebearer (Poeciliopsis baenschi), and blackspotted livebearer (P. turneri). An endemic minnow, Algansea aphanea, is also found in the ríos Coahuayana and Armerìa.
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 represents a transition between the Río Santiago  to the north and Río Balsas  to the south. It also harbors a number of endemics.
Level of taxonomic exploration
Poor, until recently. Explorations are continuing in the ecoregion.
- Lyons, J., Gonzalez-Hernandez, G., Soto-Galera, E., et al. (1998). "Decline of freshwater fishes and fisheries in selected drainages of west-central Mexico" Fisheries 23 (4) pp. 10-18.
- Abell, R. A.,Olson, D. M.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.
- Hijmans, R. J., S. Cameron and Parra., J. (2004) \WorldClim, Version 1.4 (release 3). A square kilometer resolution database of global terrestrial surface climate\ "<"[http://www.worldclim.org]">" (16 July 2009)
- Lyons, J. and Mercado-Silva, N. (1999). "Patrones taxonómicos y ecológicos entre comunidades de peces en ríos y arroyos en el oeste de Jalisco, México" Anales del Instituto de Biologia, UNAM, Serie Zoologia 70 (2) pp. 169-190.