Boundaries

This ecoregion includes drainages along the northern coasts of eastern Sumatra and western Java, separated by the Sunda Strait. It also includes the offshore islands of Bangka and Belitung.

Terrestrial habitats

The Sumatran side of the ecoregion comprises Sumatran montane rain forests [IM0159], Sumatran lowland rain forests [OM0158], Sumatran freshwater swamp forests [OM0157], Sumatran peat swamp forests [OM0160], Sunda shelf mangroves [IM1405], and Sundaland heath forests [IM0161]. The Java side of the ecoregion comprises Western Java montane rain forests [UN0167] and Western Java rain forests [IM0168] (WWF 2001).

Description of endemic fishes

This ecoregion is estimated to have around 40 endemic species, including Betta burdigala and B. chloropharynx, both of which occur on Bangka Island (M. Kottelat pers. comm. 2006).

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For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008; Kottelat et al. 1993; Kottelat & Whitten 1993). Even though this ecoregion spans different islands, they share similar fish fauna. This ecoregion also shares species with Southeastern Borneo [ecoregion 746] that are not shared with the rivers of South Central Sumatra [738] (M. Kottelat pers. comm. 2006). 

Level of taxonomic exploration

Western Java is among the areas for which data have been available since the early 19th century, but little data has been collected since the 1940s. Many species are only known from single or few localities, and have not been collected since the 1860s. As a result the exact distribution of different species is not known, and many may be extinct. The situation in southern Sumatra is similar, except that the fauna there seems richer in species and there may be fewer extinctions (M. Kottelat pers. comm. 2006).