DIVERSITY & ENDEMISM
Sundaland is one of the biologically richest hotspots on Earth, holding about 25,000 species of vascular plants, 15,000 (60 percent) of which are found nowhere else. One plant family, the Scyphostegiaceae, is confined to the hotspot and is represented by a single tree species, Scyphostegia borneensis from Borneo. There are at least 117 endemic plant genera in the hotspot; 59 of these endemic genera are found in Borneo, 17 in Sumatra, and 41 on the Malay Peninsula.
Borneo boasts a spectacular diversity of trees. There are about 3,000 species, including more than 265 species of dipterocarps; no less than 155 of these are endemic to the island. Borneo also has more than 2,000 species of orchids. The other islands are less diverse than Borneo but still boast an impressive variety of plant life. Sumatran forests include more than 100 dipterocarp species, nearly a dozen of which are endemic, and Java has more than 270 endemic orchids.
Notable plants in the hotspot include members of the genus Rafflesia, represented by 16 species with very large flowers. One of these, Rafflesia arnoldii, has the largest flowers in the world, measuring up to one meter in diameter.
Of the approximately 770 bird species that regularly occur in Sundaland, nearly 150 are endemic; around 40 of these endemic species are threatened. Borneo alone supports nearly 30 endemic species, most of which are montane species. As such, the Bornean Mountains, with 20 species confined to this EBA, are considered one of five Endemic Bird Areas (EBAs) recognized by BirdLife International in this hotspot, in addition to Sumatra and Peninsular Malaysia, Enggano, the Java and Bali Forests, and the Javan Coastal Zone.
Native species include the Bali starling (Leucopsar rothschildi, CR), a species endemic to Bali island and whose wild population fell to only six birds in 2001 due largely to trapping for the illegal cage-bird trade, and the Javan hawk-eagle (Spizaetus bartelsi, EN), estimated to number around 300-450 surviving pairs. The Javanese lapwing (Vanellus macropterus, CR), which once inhabited river deltas and marshes in the west and east, has not been recorded since 1940 and is considered Possibly Extinct.
Of Sundaland's more than 380 mammal species, over 170 are endemic to the hotspot. In addition, 17 of 136 genera are endemic. Borneo boasts the most endemic mammal species of any island in the hotspot, with over 25 species found nowhere else. Of special interest are the four Mentawai Islands off the west coast of Sumatra (Siberut, Sipora, North Pagai, and South Pagai). These small islands, covering only 5,951 km, are home to fully four endemic species of primates, including the endemic genus Simias, the pig-tailed langur.
Of all of Sundaland's diverse and threatened species, the best symbols of the vital need for conservation in the hotspot are its large mammals. The best known of these are the orang-utans, represented by two species: the Bornean (Pongo pygmaeus, EN), and the Sumatran (Pongo abelii, CR), the latter of which had an estimated 3,500 individuals surviving in the wild in Sumatra at the end of 2002. Orang-utans, which mature slowly and have a low reproductive rate, are threatened by habitat loss due to logging, fires, and agricultural conversion. Once reduced, their populations can take many years to recover.
Other famous flagships include the Proboscis monkey (Nasalis larvatus, EN), found only on Borneo, and two rhinoceros species, which are the most threatened and least known of the five surviving rhino species on Earth. The Javan rhino (Rhinoceros sondaicus, CR), which was once found throughout Southeast Asia, is now represented by only about 40-50 individuals, most surviving in Ujung Kulong National Park in West Java, with no more than six animals outside the hotspot in Nam Cat Tien National Park in Vietnam. The Sumatran rhino (Dicerorhinos sumatrensis, CR) ranged as far as Assam and Myanmar in the past. It is now believed to remain only in Sumatra, Peninsular Malaysia, and Sabah. Both rhinoceros species are severely threatened by poaching.
Reptile endemism is impressive in Sundaland. There are over 450 species of reptiles, roughly 250 of which are endemic, including 24 genera. There are also three endemic reptile families: two snake families, Anomochilidae and Xenophidiidae, and the monotypic Lanthanotidae, represented by the very rare and little known Bornean earless monitor lizard (Lanthanotus borneensis), a remnant of ancient fauna in the region. One of the most distinctive reptiles in the hotspot is the endemic false gharial (Tomistoma schlegelii, EN), a freshwater crocodilian species that can grow up to 4.7 meters in length and is found mostly in Sumatra and Borneo. Other threatened reptiles include two species of large river terrapins: the mangrove terrapin (Batagur baska, CR) and the painted terrapin (Callagur borneoensis, CR). Both species inhabit creeks and estuaries and have been extirpated from large portions of their range. The hotspot is also home to several Endangered and Vulnerable species of tortoises and freshwater turtles.
The Sundaland hotspot is home to more than 240 species of amphibians, nearly 200 of which are endemic. Seven genera are endemic, including the slender toads (Leptophryne, comprising two species), and three with single species: Pseudobufo, Phrynella, and Gastrophrynoides. The amphibian fauna of Sundaland remains extremely poorly known, and Sumatra, in particular, represents a very high research priority.
Nearly 200 species of fish have been discovered in the rivers, lakes and swamps of Sundaland in just the last decade. There are currently about 1,000 known species of freshwater fish in the hotspot (out of a projected 1,400), more than a quarter of which are restricted to one or more of the main islands. Once again, Borneo tops the list, with about 430 species, more than 160 of which are endemic. One of the best known fish species in the hotspot is the dramatic Asian bony tongue or golden arowana (Scleropages formosus, EN), a highly prized aquarium fish that can sell for thousands of dollars per animal.