Boundaries

This ecoregion encompasses the whole Song Hong (Red River) basin in Vietnam, China, and Laos. It flows in a southeasterly direction from the Yunnan Province in southern China to the Gulf of Tonkin near Hanoi, Vietnam.

Terrestrial habitats

Terrestrial ecoregions that occur in this ecoregion include: Northern Indochina subtropical forests, Yunnan Plateau subtropical evergreen forests, South China-Vietnam subtropical evergreen forests, Red River freshwater swamp forests, and Northern Vietnam lowland rain forests (Wikramanayake et al. 2002).

Description of endemic fishes

The ecoregion contains 16 recorded endemic species in the Cyprinidae, Balitoridae and Sisoridae families. Some species restricted to the basin include Schistura macrotaenia, Placocheilus caudofasciatus, and Glyptothorax quadriocellatus.

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For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008). This ecoregion includes the whole Song Hong (Red River) basin, as well as several extensive karstic areas, with underground systems and endorheic basins. Many noted widespread species throughout East Asia may in fact be represented by distinct species in the Song Hong basin. The exact position of the boundary between Song Hong and Northern Annam ecoregion [760] is not settled due to a lack of usable data. Part of Hainan Island [eco 759] might belong to this ecoregion, but more data is required (M. Kottelat pers. comm. 2006).

Level of taxonomic exploration

The ecoregion is still poorly surveyed. The reliability of published data varies, especially from Vietnam (M. Kottelat pers. comm. 2006).