Boundaries

This ecoregion covers the highlands of central Borneo, including portions of Sarah and Sarawak in Malaysia and North, East, Central and West Kalimantan in Indonesia.

Terrestrial habitats

Terrestrial ecoregions include Borneo montane rain forests [IM0103], Borneo lowland rain forests [IM0102], as well as an area of Borneo peat swamp forests [IM0104] and Sundaland heath forests [IM0161] in the upper Kapuas basin.

Description of endemic fishes

The ecoregion includes nearly 10 recorded endemic species. However, it is estimated that numbers may be closer to 50 endemic species (M. Kottelat pers. comm. 2006). It also contains an endemic genus (Hypergastromyzon) represented by two species (H. eubranch and H. humilis) and near-endemic genera (Gastromyzon, Glaniopsis, Protomyzon, Parhomaloptera) in the family Balitoridae.

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For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008; Inger & Chin 1962; Kottelat et al. 1993; Popta 1906). The highlands of Borneo host a number of genera and species that are either endemic or closely related to taxa of the Annamite Cordillera, Hainan, and South China. Diversity seems to decrease from north to south. This ecoregion is tentatively recognized as a distinct ecoregion, but it is unclear if this is a single ecoregion, an assemblage of smaller regions, or whether it should be simply considered as part of Kapuas [ecoregion 741], Southeastern Borneo [746], Eastern Borneo [745], Northeastern Borneo [744], or Northwestern Borneo [742] because they have a mosaic distribution (M. Kottelat pers. comm. 2006).

Level of taxonomic exploration

The data of this ecoregion is still very fragmentary and restricted to a few localities in the Mahakam headwaters and Sabah (M. Kottelat pers. comm. 2006).