DIVERSITY & ENDEMISM
The patterns of biological diversity in Indo-Burma have resulted from the interaction of topography, past climate changes, soil characteristics, and the hotspot's patterns of seasonal rainfall. The hotspot contains many localized centers of endemism, particularly montane isolates, but also areas of lowland wet evergreen forest that were isolated at some stage, and river basins.
Knowledge of plant species within the Indo-Burma hotspot is uneven and is hampered by socio-political divisions and taxonomic complications. A conservative estimate of total plant diversity in the hotspot reveals about 13,500 vascular plant species, of which about 7,000 (52 percent) are endemic. Among the flora of the Indo-Burma Hotspot are a wide array of orchid and ginger species (there are more than 1,000 orchid species in Thailand alone) and many tropical hardwood trees, including commercially valuable dipterocarp species and teak (Tectona grandis).
There are over 1,260 bird species found in Indo-Burma; more than 60 of these are endemic. The hotspot also has five endemic bird genera, each represented by a single species: golden-crested myna (Ampeliceps coronatus), short-tailed scimitar-babbler (Jabouilleia danjoui) and wedge-billed wren-babbler (Sphenoicichla humei).
BirdLife International has identified eight Endemic Bird Areas (EBAs) that fall either partially or entirely within the hotspot. Threatened bird species in these EBAs include white-eared night-heron (Gorsachius magnificus, EN), which occurs in southeastern China and north-eastern Vietnam, Edwards's pheasant (Lophura edwardsi, EN) of the wet evergreen forests in the Annamese Lowlands of Vietnam, orange-necked partridge (Arborophila davidi, EN) of the South Vietnamese Lowlands, and grey-crowned crocias (Crocias langbianis, EN) of Vietnam's Da Lat Plateau.
Gurney’s pitta (Pitta gurneyi, CR), a lowland evergreen forest bird endemic to Peninsular Thailand and adjacent parts of southern Myanmar, underwent a dramatic decline during the twentieth century due to extensive habitat loss. Although, by the end of the century it was known to persist in only a single location in Thailand, a significant population of the bird has recently been rediscovered in Myanmar, thereby increasing the likelihood that this Critically Endangered species may survive. Although not endemic to Indo-Burma, the majority of the world population of green peafowl (Pavo muticus, VU) is also found within the hotspot. This species has undergone a serious decline over the last century as a result of hunting and expansion of human populations into natural landscapes, particularly the spread of human settlements along permanent water sources.
The rivers and floodplain wetlands of the Indo-Burma hotspot are tremendously important for the conservation of a number of widespread bird species that have recently suffered dramatic population declines across their distributions. These include large waterbirds, such as spot-billed pelican (Pelecanus philippensis, VU), greater and lesser adjutant (Leptoptilus dubius, EN and L. javanicus, VU) and sarus crane (Grus antigone, VU), wet grassland specialists, such as Bengal florican (Houbaropsis bengalensis, EN), and riverine specialists such as Indian skimmer (Rhynchops albicollis).
There are about 430 mammal species in the hotspot; more than 70 species and seven genera are endemic. There is also an endemic family, the Craseonycteridae, represented by a single species, Kitti's hog-nosed bat (Craseonycteris thonglongyai), which is one of the world's smallest mammals, being no larger than a bumblebee.
An indication of the relative lack of knowledge about mammal diversity in the hotspot is the number of species that have only recently been discovered. In just the last 12 years, six large mammal species were discovered in the hotspot, five of them in the Annamite Mountains: the saola (Pseudoryx nghetinhensis, EN), large-antlered muntjac (Muntiacus vuquangensis), Annamite muntjac (M. truongsonensis), grey-shanked douc (Pygathrix cinerea) and Annamite striped rabbit (Nesolagus timminsi). The sixth species, the leaf deer (Muntiacus putaoensis) occurs in the mountains of northern Myanmar and adjacent north-east India.
The saola represents a newly described endemic genus, and is one of several species within the Indo-Burma hotspot in need of immediate conservation action. Confined to the wet evergreen forests in the Annamite lowlands of Vietnam and the Lao P.D.R., saola is under threat from severe habitat degradation and conversion, as well as indiscriminate snaring, which may increase with ongoing road construction projects in its habitat. Although there was much global attention on the saola after its discovery, none of its populations have yet been placed under effective conservation management. Another endemic flagship species is kouprey (Bos sauveli, CR), which may have already become the first of the wild cattle species to become extinct as a result of human activities. Three other threatened wild cattle species can be found in the hotspot.
Indo-Burma hosts many endemic primate species, including three species of douc, namely red-shanked douc (Pygathrix nemaeus, EN), grey-shanked douc and black-shanked douc (P. nigripes, CR), as well as Tonkin snub-nosed monkey (Rhinopithecus avunculus, CR) white-rumped black leaf monkey or Delacour's leaf monkey (Trachypithecus delacouri, CR), and white-headed langur (T. poliocephalus, CR) , whose populations numbers only in the hundreds. The hotspot is also home to several endemic species of gibbons.
Nearly 520 reptile species are found in the hotspot; 12 genera and over 200 species are endemic. Nine of the endemic genera are represented by a single species, among them a recently described pit viper from Vietnam (Triceratolepidophis sieversorum). Endemism is especially high among snakes of the Colubidae family.
Indo-Burma also supports probably the highest diversity of freshwater turtles in the world: 53 species, representing one-fifth of the world's species. An example is the striped narrow-headed softshell turtle (Chitra chitra, CR), which can grow to more than 120 centimeters in length and is the largest freshwater turtle species in the world. Including tortoises, the number of species in the hotspot is 57. Populations of freshwater turtles and tortoises have declined dramatically worldwide. Approximately 200 of the 300 known species are globally threatened; constituting a global crisis. The situation is particularly severe in the Indo-Burma hotspot, where overexploitation for the wildlife trade is the most significant threat. No less than 39 species of freshwater turtles (43 including tortoises) are threatened with extinction. Of the 22 Critically Endangered non-marine turtles globally, 9 occur in this hotspot, including the Vietnam leaf turtle (Mauremys annamensis, CR), river terrapin (Batagur baska, CR), Arakan forest turtle (Heosemys depressa, CR), striped narrow-headed softshell turtle, Chinese three-striped box turtle (Cuora trifasciata, CR), painted terrapin (Callagur borneoensis, CR), and Burmese star tortoise (Geochelone platynota, CR).
Other notable reptiles are the endemic Siamese crocodile (Crocodylus siamensis, CR), and the butterfly lizards of the genus Leiolepis. Chinese crocodile lizard (Shinisaurus crocodilurus) is another notable reptile species. The sole member of the family Shinisauridae, it is most closely related to the lizards of the genus Xenosaurus in southern Mexico and Guatemala.
There are more than 280 amphibian species in the Indo-Burma hotspot, over 150 of which are endemic. However, high endemism does not extend to the genus level; only three of 46 genera are restricted to the hotspot, namely Ophryophryne, Bufoides, and Glyphoglossus. Bufoides and Glyphoglossus comprise single species: the Khasi Hills toad (B. meghalayanus, EN) is known from only a few sites in northeastern India, while the last-mentioned (G. molossus) is localized but widespread in the hotspot.
There are numerous other remarkable and endemic frog species that occur. Several groups such as the Rhacophorus gliding frogs, the megophryid litter toads, and various ranid groups stand out for their local evolutionary radiations, conservation concern, and eyecatching appearance. Salamander diversity is not very high in the hotspot, but the salamanders contain a high proportion of species with very restricted ranges and of high conservation concern, including four endemic species in the genus Paramesotriton, two of which are globally threatened: the Vietnamese salamander (P. deloustali, EN), and Guangxi warty newt (P. guangxiensis, VU).
Indo-Burma has a remarkable freshwater fish fauna, with more than 1,260 documented species, or about 10 percent of the world’s freshwater fishes. More than 560 of these species are endemic, as are 30 genera and one family, the Indostomidae, or armored sticklebacks, a family of strange fishes that may be remotely related to the marine seamoths.
Among the hotspot's native fish species are some of the largest freshwater fishes in the world. The Tonle Sap Lake and deep pools of the Mekong River are key habitats for Mekong giant catfish (Pangasianodon gigas, CR), and Jullien's golden carp (Probarbus jullieni, EN).