Boundaries

This ecoregion is a transition zone between the low lying Orinoco Llanos [307] and the Orinoco High Andes [305].  It extends from the Amazon-Orinoco drainage divide just south of the Serrania de la Macarena to the eastern edge of the Mérida Andes along the western and northern flanks of the Orinoco basin. 

Topography

This ecoregion follows the eastern slopes of the Eastern Cordillera of the Columbian Andes and Mérida Andes to the Cordillera de la Costa. Elevations range from 148 m along the fringing floodplains to over 2200 m asl.

Freshwater habitats

This ecoregion includes moderate and steep gradient streams and rivers that flow from the Andes. There are also high gradient headwater and upland streams and a few natural mountain lakes, including the endorheic Lago Valencia. Upland trunk streams in the Apure, Meta, and Guaviare systems are shallow and rocky, whereas larger streams carry heavy sediment loads.

Terrestrial habitats

Terrestrial habitats grade from llanos grasslands at lower elevations to dry and montane forests at higher elevations. The southern extreme is flanked by the Caqueta moist forests. In the north the La Costa xeric shrublands surround the montane forests of the Cordillera de la Costa.

Description of endemic fishes

The endemic fish fauna of this region is currently composed of nine species: five catfish, Astroblepus marmoratus, Lithogenes valencia, Phenacorhamdia taphorni, Trichomycterus dorsostriatum, and Centromochlus reticulates (Siluriformes); two characids, Hyphessobrycon otrynus and Creagrutus gyrospilus (Characiformes); a ghost knifefish, Apteronotus galvisi, confined to the Rio Meta basin (Gymnotiformes); and a silverside, Atherinella venezuelae (Atheriniformes).

Justification for delineation

This is a transitional zone between the llanos and high mountain streams with unique assemblage of transitional fish fauna. It lies within the Orinoco ichthyographic province outlined by Ringuelet (1975) and Gery (1969).

Level of taxonomic exploration

Poor