Boundaries

This ecoregion encompasses the entire Lake Maracaibo drainage system, including the lake and rivers feeding it from surrounding mountain ranges.

Topography

Lake Maracaibo is surrounded by the Perijá Andes (Venezuela and Colombia) to the west, the Mérida Andes (Venezuela) to the south and southeast, and the west end of the Venezuela coastal ranges to the east. Elevations range from sea level to more than 4600 m asl.

Freshwater habitats

The vast Lake Maracaibo dominates the basin.  The lake has a maximum depth of 35 m and is a mix of mildly saline waters (2-7%) and freshwater (mostly in the southwest). The lake is fed by relatively small river basins with high-gradient headwaters in the mountains and short lower courses that cross a narrow plain; some floodplain lakes are in the southwest.

Terrestrial habitats

Terrestrial habitats include xeric scrub, dry forests, moist forests, montane forests, and páramo.

Description of endemic fishes

Of the 66 endemic species found in the Maracaibo basin, 65% are represented by Siluriformes, of which 73% are endemic to the basin.  Two monotypic genera, Perrunichthys (Pimelodidea) and Doraops (Doradidae), are endemic to the basin. More than half of the Gymnotiformes (55%) and 40% of all Characiformes present in the Maracaibo basin are endemic.  Within the Siluriformes, 100% of the trichomycterids (6 species), 75% of pimelodids (6 species) and 65% of loricarids (19 species) are endemic.  Examples of endemics include Cyphocharax aspilos (Curimatidae); Creagrutus maracaiboensis, Cynopotomus venezuelae, and Mylossoma acanthogaster (Characidae); Rhinodoras thomersoni and Doraops zuloagai (Doradidae); Platysilurus malarmo, Perrunichthys perruno, Cheirocerus abuelo (Pimelodidae); Batrachoglanis acanthochiroides (Pseudopimelodidae); Xiliphius kryptos and Hoplomyzon atrizona (Aspredinidae); and Farlowella curtirostra and F. taphorni (Loricariidae).

Justification for delineation

This ecoregion is an isolated drainage system with high endemicity. It falls within the Maracaibo ichthyographic province identified in Ringuelet (1975).

Level of taxonomic exploration

Good