Boundaries

This ecoregion extends across Costa Rica and Panama, from the Tulín and Parrita-Candelaria drainage basins in the northwest to the western limit of the San Pablo and San Pedro drainage basins to the east.

Topography

The ecoregion is bounded by the Cordillera de Talamanca and the Cordillera Central, with elevations reaching over 3500 m above sea level. Southwest of the Cordillera de Talamanca are the interior valleys of the Rio General and the Rio Coto. These valleys are separated from the coastal plain by two ridges that form the Cordillera Costeña, a set of two hilly areas that for the most part lie below 1000 m in elevation, but have peaks that extend up to 1700 m. Protruding from the coast are the Peninsula de Osa and Peninsula Burica. The Peninsula de Osa forms the southwestern boundary of the Golfo Dulce, and Peninsula Burica is bisected by the Panama-Costa Rica border (Savage 2002). Peninsula Burica forms the western boundary of the Golfo de Chiriquí.

Freshwater habitats

Along the Pacific coast the ecoregion is marked by short, impetuous streams and few estuaries. Many of these short rivers empty directly into the Pacific Ocean or the Golfo Dulce. In the north is the Rio Grande de Pirris, a tributary of the Rio Parris that flows through deep gorges with steep, barren sides and later flows through dense forests. The lower valley of the Pirris is coverd by red clay, and thus unable to absorb rainwater. Since the waters do not readily drain off, they become stagnant (Keltie 1897). 

Another principal river system includes the southeastward-flowing Rio General (Chirripo) and the northwestward-flowing Rio Coto. These streams drain the southern slopes of the Cordillera de Talamanca and the northern slopes of the Cordillera Costeña. At their confluence near Potrero Grande the rivers become Rio Grande de Térraba, which runs through a deep, narrow gorge in the Cordillera Costeña toward the narrow coastal plain. At the mouths of the rios Térraba and Sierpe lie an extensive wetland system. The Térraba system has high stream flow most of the year, although it declines greatly during the dry season from January through April. In comparison, the Rio Grande de Pirris experiences more cyclic seasonal fluctuations (Savage 2002).

The rivers of the Pacific versant of Panama, located in the southeastern part of the ecoregion, are long and slow due to a shallower gradient and more extensive basins (Harmon 2005).

Terrestrial habitats

The lower elevations of the ecoregion are dominated by Isthmian-Pacific moist forests, whereas higher elevations are covered by Talamancan montane forests. An extensive mangrove area lies at the mouths of the Térraba and Sierpe rivers.

Description of endemic fishes

The high endemicity of the Chiriquí province (30%) is probably the result of its increasing isolation from other freshwater ecoregions over geologic time. The hypothesis of increasing evolutionary independence of the Chiriquí and Santa Maria [208] ecoregions is supported by molecule-based phylogeographic analysis of widespread taxa across the LMA landscape (Bermingham and Martin 1998; Perdices et al. 2002). The endemic species of the Chiriquí ecoregion include six characids, Bryconamericus terrabensis, Hyphessobrycon savagei, Pseudocheirodon terrabae, Pterobrycon myrnae, Roeboides ilseae, and Astyanax kompi; one lebiasinid, Piabucina boruca; one eleotrid, Eleotris tecta; and three rivulids, Rivulus glaucus, R. siegfriedi, and R. uroflammeus. It also contains the following secondary freshwater fishes: two cichlids, Amphilophus lyonsi and Archocentrus sajica; and three poeciliids, Brachyrhaphis terrabensis, Poeciliopsis paucimaculata, and P. retropinna.

Other noteworthy fishes

The semaphore tetra (Pterobrycon myrnae) is a relict species. The only other member of the genus is P. landoni, known from a single specimen collected in Colombia.

Justification for delineation

Fish provinces from Bussing (1976) were revised and subdivided on the basis of application of a similarity index to sub-basin fish presence/absence data.

Level of taxonomic exploration

The level of taxonomic exploration is good in this region.