DIVERSITY & ENDEMISM
Wallacea has very high numbers of species found nowhere else in the world, in part because it is tropical and made up of many islands and in part because of its complex geological history. The land fragments of Wallacea separated from mainland Asia around 200 million years ago, contributing to their isolation and the evolution of many unique species. The hotspot lies between the Indo-Malayan and Australasian biogeographic realms and includes representatives from each of these regions as well as many endemics in its own right.
Although the flora of this island region is not well known, it is estimated that there are about 10,000 species of vascular plants, with roughly 1,500 endemic species (15 percent) and at least 12 endemic genera. There are about 500 endemic species on Sulawesi, 120 on the Lesser Sudas and 300 on the Moluccas.
The wetter lowland and hill forests have the highest number of tree species, but differ from the commercially valuable forests of Sundaland in having only a handful of dipterocarp species. The major trees of commercial value are the tall kauri (Agathis spp.), the magnificent yellow-flowered legume Pterocarpus indicus in the more seasonal areas, and the gum tree Eucalyptus deglupta, usually found in riverine habitats and used extensively in reforestation projects.
There are about 650 regularly occurring bird species in Wallacea, and roughly 265 (40 percent) of these are endemic. There are also 29 endemic genera. Endemism is significant at the level of individual islands; Sulawesi has the largest fauna, with 356 species, including 96 endemics, among them the maleo (Macrocephalon maleo, EN), a distinctive megapode currently thought to number between 4,000 and 7,000 breeding pairs. These chicken-like birds build mounds in which they bury their eggs, and, three months later, the young explode out of the mound already feathered in adult plumage.
The maleo is but one of some 50 bird species threatened with extinction in this hotspot, including the caerulean paradise-flycatcher (Eutrichomyias rowleyi, CR), which was thought to be extinct until its rediscovery in 1998. The species is confined to remnant patches of forest at the base of Gunung Sahendaruman on Sangihe, north of Sulawesi, and is thought to number between 19 and 135 birds. Another species confined to Sangihe is the Sangihe white-eye (Zosterops nehrkorni, CR) known only from a single historical specimen, but for which there has been a spate of recent sightings around Gunung Sahenduraman.
As a testimony to the diversity and endemism of Wallacea, ten Endemic Bird Areas (EBAs) have been identified within the hotspot by BirdLife International.
More than 125 of Wallacea's 220-plus mammal species are found nowhere else in the world. Only the Madagascar and Sundaland hotspots have a higher level of mammal endemism. If endemism is recalculated excluding the region's more than 125 species of bats (because they disperse easily), the level of mammal endemism is an astonishing 88 percent.
One of the most unusual mammals in Wallacea is the babirusa (Babyrousa babyrussa, VU). Babirusas (literally "pig-deer" in Bahasa-Indonesian) are pig-like animals characterized by the male's long recurved tusks that penetrate the upper lip. Two species of anoas, or dwarf buffaloes, are endemic to the forests of Sulawesi: the lowland anoa (Bubalus depressicornis, EN) and the mountain anoa (Bubalus quarlesi, EN).
There are a number of endemic primates in the hotspot. The island of Sulawesi is home to at least seven species of endemic macaques and at least five species of endemic tarsiers. Tarsiers are tiny, goggle-eyed creatures that resemble mammalian tree frogs more than monkeys.
Unfortunately, about one-third of endemic mammals in this hotspot are threatened with extinction. Besides the aforementioned babirusa and the anoas, this includes the Sulawesi palm civet (Macrogalidia musschenbroekii, VU), which as the name suggests is found only on Sulawesi in lowland and montane forests to 2,600 meters, and around 25 species of rodents.
Wallacea's reptile species total more than 220 species, nearly 100 of which are confined to the hotspot. There are also three endemic genera, all snakes: Calamorhabdium, with two species, and Rabdion and Cyclotyphlops, both monotypic.
The best-known reptile species in Wallacea is the Komodo dragon (Varanus komodoensis, VU), the largest lizard in the world, with males that can grow up to 2.8 meters in length and weigh about 50 kilograms. The lizard is found only on the islands of Komodo, Padar, Rinca and Flores in the Lesser Sundas, the driest portion of Indonesia.
Only a single turtle species is found in this hotspot, the recently described McCord's sideneck turtle or Roti Island snake-necked turtle (Chelodina mccordi, CR). This species is the western-most occurring species of the family Chelidae, a dominant turtle group from Australia and New Guinea. This species occurs only in three separate populations on a single small island (Roti) with 70 km² of available habitat.
Nearly 50 amphibian species, all frogs, are native to Wallacea; more than 30 of these are endemic, including the Sulawesi toad (Bufo celebensis) and Oreophryne monticola (EN). The latter is one of eight threatened species present in the hotspot; the remaining seven species are all endemic: Oreophryne celebensis (VU); O. variabilis (VU); Nyctimystes rueppelli (VU); Callulops kopsteini (EN); Limnonectes arathooni (EN); Limnonectes heinrichi (VU); and Limnonectes microtympanum (EN).
Nearly all of the more than 300 freshwater fish species found in Wallacea are tolerant of both fresh and saltwater. About 75 of these species are endemic to the hotspot. On the island of Sulawesi alone, there are nearly 70 known fish species, about three-quarters of which are endemic. The deep lakes, rapids, and rivers that make up the Malili Lakes in South Sulawesi have at least 15 endemic and quite beautiful telmatherinid fishes, two of them representing endemic genera, three endemic Oryzias, two endemic halfbeaks, and seven endemic gobies.
Most of the invertebrate fauna of Wallacea remains poorly known, except for the enormous bird-wing butterflies, which are members of the swallowtail butterfly family. There are more than 80 species of birdwings in Wallacea, more than 40 of which are endemic. One species, Ornithoptera croesus (EN), which is endemic to the northern Moluccas, has a wingspan of nearly 20 centimeters in females. There are also 109 tiger beetles recorded from this hotspot, 79 of which are endemic. The northern Moluccas also contains the world's largest bee (Chalocodoma pluto) with females that can grow as large as four centimeters in length.