Boundaries

This ecoregion encompasses the southernmost drainages of Borneo that empty into the Java Sea, from the Negara drainage in the east to the Jelai-Kendawangan drainage in the west. The ecoregion lies predominantly in the Indonesian province of Central Kalimantan, but also crosses into South Kalimantan and West Kalimantan.

Terrestrial habitats

Terrestrial ecoregions in Southeastern Borneo include the Borneo lowland rain forests [IM0102], Sundalan heath forests [IM0161], Borneo peat swamp forests [IM0104], Southwest Borneo freshwater swamp forests [IM0153], Sunda Shelf mangroves [IM1405], and an area of Borneo montane rain forests [IM0103] (WWF 2001).

Description of endemic fishes

Eighteen endemics have been recorded, but there may be as many as 40 (M. Kottelat pers. comm. 2006). Genera with multiple endemic species include Hemirhamphodon (Hemiramphidae), Parosphromenus (Osphronemidae), Rasbora (Cyprinidae), Sphaerichthys (Osphronemidae), and Sundasalanx (Sundasalangidae).

Justification for delineation

For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008; Kottelat et al. 1993; Kottelat & Whitten 1993). The little published data suggest the presence of a number of endemic species. In addition, the aquatic fauna of this ecoregion has zoogeographic affinities with Southern Sumatra - Western Java [ecoregion 739] (M. Kottelat pers. comm. 2006).

Level of taxonomic exploration

Although there had been some surveys conducted in some basins (especially the Barito basin), data have not been available. The species richness can only be estimated, and little is known of its composition (M. Kottelat pers. comm. 2006).