Biodiversity and Endemism
The patterns of biological diversity in Indo-Myanmar 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.
Plants: 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 (see table). Among the flora of the 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.
Birds: There are over 1,260 bird species found in Indo-Myanmar; more than 60 of these are endemic. The hotspot also has five endemic bird genera, each represented by a single species: golden-crested myna, short-tailed scimitar-babbler, and wedge-billed wren-babbler. BirdLife has identified eight Endemic Bird Areas that fall either partially or entirely within the hotspot. Threatened bird species in these EBAs include white-eared night-heron, which occurs in southeastern China and northeastern Vietnam, Edwards’ pheasant of the wet evergreen forests in the Annamese Lowlands of Vietnam, orange-necked partridge of the South Vietnamese Lowlands, and grey-crowned crocias of Vietnam’s Da Lat Plateau. The rivers and floodplain wetlands of the 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, greater and lesser adjutant, and sarus crane, wet grassland specialists, such as Bengal florican, and riverine specialists such as Indian skimmer.
Mammals: 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, 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. Since the early 1990s, six large mammal species were discovered in the hotspot, five of them in the Annamites: the saola, large-antlered muntjac, Annamite muntjac, grey-shanked douc, and Annamite striped rabbit. The sixth species, the leaf deer occurs in the mountains of northern Myanmar and adjacent north-east India. Indo-Myanmar hosts many endemic primate species, including the red-shanked, grey-shanked, and black-shanked doucs, the Tonkin snub-nosed monkey, Delacour’s langur, and golden-headed (Cat Ba) langur, whose total populations number only in the hundreds. The hotspot is also home to several endemic species of gibbon.
Reptiles: Indo-Myanmar 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, which can grow to more than 120 cm 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. The situation is particularly severe in the hotspot, where overexploitation for the wildlife trade is the most significant threat. No less than 43 species of freshwater turtles and tortoises are threatened with extinction. Of the 22 Critically Endangered non-marine turtles globally, nine occur in this hotspot, including the Vietnam leaf turtle, river terrapin, Arakan forest turtle, striped narrow-headed softshell turtle, Chinese three-striped box turtle, and Myanmar star tortoise.
Freshwater fishes: Indo-Myanmar 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 world’s largest freshwater fishes. The Tonle