Zoogeography and biodiversity of the freshwater fishes of Southeast Asia

Abstract

The ichthyofauna of the freshwater system of Southeast Asia is extremely diverse. A recent estimate of about 1000 species is probably an understatement. More than 10 new species are being added to the list annually. The distribution pattern of the Southeast Asian freshwater fishes can be divided into five zoogeographic regions. The first one is the Salween basin in Burma, with fishes mainly of the Indian subcontinent origin such as Amblypharyngodon atkinsoni, Bangana almorae and Brachydanio jayarami. The second zoogeographic area is the Mekong, Chao Phraya and Mae Khlong drainages which harbour fishes typical of the mainland of Southeast Asia such as Acanthorhodeus deignani, Barbichthys nitidus and Cirrhinus siamensis. The Malay Peninsula is the third region whose species composition is heavily influenced by the Siamese (such as Homaloptera smithi, Tuberoschistura baenzigeri and Botia beauforti) and Indonesian (such as Botia hymenophysa, Luciocephalus pulcher and Parosphromenus deissneri) elements. The islands of Sumatra, Borneo and Java are the fourth zoogeographic area of fish distribution. These islands show a high degree of endemism, especially in fishes of the family Belontiidae. Finally, the freshwater system of the Philippines is the last zoogeographic region of Southeast Asia. The area is characterized by the presence of closely related species of the cyprinids especially in Lake Lanao. Currently, high diversity of these freshwater fishes is being threatened by land development, such as deforestation, road construction and land expansion for plantation. Recent studies in the Gombak River basin show the extermination of 41 per cent of native fish species from 1969 to 1990. This is probably due to the construction of highways, logging, as well as land clearing for agriculture.

Phylogeography of the Mekong mud snake (Enhydris subtaeniata): the biogeographic importance of dynamic river drainages and fluctuating sea levels for semiaquatic taxa in Indochina

“…Dodson et al (1995) and McConnell (2004) documented genetic evidence of similar Pleistocene connections via paleo-drainages on the Sunda Shelf for freshwater fish. In addition, faunal similarities between the Chao Phraya and Lower Mekong (Taki 1975; Zakaria–Ismail 1994; Rainboth 1996) support this connection.…”

Species composition and length-weight relationship of fishes in the Candaba wetland on Luzon Island, Philippines

“…Followed by two species of gobiids and osphronemiids, the cyprinids with six species were by far the most dominant fishes sampled. Other tropical wetlands in Southeast Asia support a variety of cyprinids, which reflects their high degree of endemicity in the region (Zakaria‐Ismail, 1994). The great number of cyprinid species in the Candaba wetland and elsewhere in the Philippines are the result of species introductions in support of the government’s food production programs in previous years (Welcomme, 1981).…”

Mapping China's freshwater fishes: diversity and biogeography

“…China's freshwater fish fauna, which is characterized by the dominance of Cyprinidae, includes a part of the Oriental subregion of the Indian Region (south and south-west parts of China) and a part of the Central Asia subregion of the Palearctic Region (north, east and middle parts of China) (Rainboth 1991;Reshetrukov and Shakirova 1993;Jayaram 1999). In the interglacial periods, species spread back to the north, resulting in the formation of dispersal species and relict species (Zakaria-Ismail 1994;Chang et al 1996;Chang and Chen 2000). A 400-million-year-old fossil fish Psarolepis romeri, Incertae sedis, considered as the origin of bony fishes, was discovered in Southwest China (Yu 1998;Zhu et al 1999).…”