DIVERSITY & ENDEMISM
The hotspot holds nearly 7,600 species of plants, of which more than 2,350 are endemic. The Eastern Arc Mountains have over 1,100 species of endemic plants, as well as about 40 endemic plant genera. Endemism is lower in the Southern Rift, with perhaps only 100 species endemic. However, the grasslands of the Southern Rift are particularly rich in orchids including more than 500 species, and plants of the genus Protea. The Nyika Plateau supports nearly 215 orchid species, of which about four species and two subspecies are endemic.
The Albertine Rift is home to about 14 percent (about 5,800 species) of mainland Africas plant species, with more than 550 endemic species, including three endemic genera: Afroligusticum, Micractis, Rhaesteria. The Ethiopian Highlands harbor an estimated 5,200 plant species, of which 555 are endemic. The genus Senecio is particularly diverse, with half of the two dozen species found nowhere else. This area also has a monotypic endemic genus, Nephrophyllum abyssinicum, which is found on heavily grazed pastures, open ground, and rocky areas on steep slopes between 1,650 and 2,700 meters.
Among the hotspot's best-known flowering plants are the African violets (Saintpaulia spp.), with up to 20 endemic species in the Eastern Arc Mountains. There are also about 13 endemic species of African primroses (Streptocarpus spp.) in the Eastern Arc Mountains, and 18 endemic species of Impatiens in the Albertine Rift.
The high plateaus of the Ethiopian Highlands are home to the giant Lobelia rhynchopetalum, which grows to a height of about 2-3 meters before sending up a single inflorescence of dark blue-purple flowers that can reach a height of 9 meters. Every few years, the lobelias have a musth year when the great majority of plants flower.
About 1,300 bird species occur in the Eastern Afromontane Hotspot, and about 110 of these are found nowhere else.
The Eastern Arc and Southern Rift Mountains form a single Endemic Bird Area, as defined by BirdLife International. Several of the areas endemic birds have very limited ranges; for example, the Taita thrush (Turdus helleri, CR) and Usambara akalat (Sheppardia montana, EN), occur only in a few square kilometers of forest in the Taita Hills and West Usambaras, respectively, while the Uluguru bush-shrike (Malaconotus alius, EN) lives only in a single forest reserve in the Uluguru Mountains. Nyika National Park on the Nyika Plateau in the Southern Rift supports the worlds largest breeding population of blue swallow (Hirundo atrocaerulea, VU).
The Albertine Rift is extremely rich in birds, providing a home for over half of Continental Africas birds more than 1,060 species in 368 genera. This includes more than 40 endemic species and three endemic genera, Pseudocalyptomena, Graueria, and Hemitesia. Two Endemic Bird Areas are included within the Albertine Rift. The stunning Rwenzori turaco (Musophaga johnstoni), found in ten forest islands of the Albertine Rift, has a mantle of iridescent green, orange-yellow cheeks, blue back and tail, and bright red primary feathers. The beautiful, bright green African green broadbill (Pseudocalyptomena graueri, VU), the sole representative of a monotypic genus, is found in only three sites in the Rift.
About 680 species of birds are found in the Ethiopian Highlands, nearly 30 of which are endemic. Five of these endemic species are restricted to tiny areas in the Southern Highlands. The Southern Highlands and the Central Ethiopian Highlands are both Endemic Bird Areas. Four endemic bird genera are found in this part of the hotspot, including three that are widespread (Cyanochen, Rougetius, and Parophasma) and one that has a very localized distribution in the south (Zavattariornis). The blue-winged goose (Cyanochen cyanoptera) is related to the sheldgeese of the alpine and temperate grasslands of South America. The striking Prince Ruspolis turaco (Tauraco ruspolii, VU) is threatened by declining habitat.
The Eastern Afromontane Hotspot is home to nearly 500 mammal species, more than 100 of which are endemic to the region. Although several of Africas larger flagship mammals, including the elephant (Loxodonta africana, VU), and leopard ( Panthera pardus), are found in this hotspot, the majority of threatened species are primates and smaller mammals.
Three species of primates are endemic to the Eastern Arc Mountains and Southern Rift, the Sanje mangabey (Cercocebus sanjei, EN), the Udzungwa red colobus (Procolobus gordonorum, VU) and the mountain dwarf galago (Galagoides orinus). Six shrew species are endemic to this part of the hotspot, including the desperate shrew (Crocidura desperate, CR), found only in the Udzungwa and Rungwe Mountains. Other notable mammals in the Eastern Arcs include Abbotts duiker (Cephalophus spadix, VU) and the eastern tree hyrax (Dendrohyrax validus, VU). Several new mammal species have also been discovered in recent years, including two possibly new species of dwarf galago (Galagoides spp.) on the Taita Hills and on Mt. Rungwe and potentially a new mangabey species endemic to the Udzungwa Mountains.
Nearly 40 percent of Continental Africas mammals are found in the Albertine Rift more than 400 species, of which 35 are endemic. Most of these endemic mammals are shrews and rodents, including two monotypic endemic genera: the Ruwenzori shrew (Ruwenzorisorex suncoides, VU), and Delanys swamp mouse (Delanymys brooksi).
However, the most charismatic flagship species of the Albertine Rift, and indeed of the entire hotspot, are the great apes. The well-known mountain gorilla (Gorilla beringei beringei, CR) is restricted to about 380 individuals in the Virungas. Grauers gorilla (G. b. graueri, EN), was estimated to number about 16,900 in eastern DRC in 1996, but has since suffered major declines as a result of hunting, habitat loss and degradation related to civil war, logging, forest clearance for agriculture, and mining for gold, diamonds, and coltan. Although there are robust chimpanzees (Pan troglodytes schweinfurthii) in many of the Albertine Rift forests, their populations are generally small.
The forests of the Albertine Rift are also home to at least 27 other primate species, including lHoests monkey (Cercopithecus lhoesti), the owl-faced monkey (C. hamlyni), and the golden monkey ( C. mitis kandti). Other mammals iinclude the Ruwenzori duiker (Cephalophus rubidus, EN), which is restricted to the Rwenzori Mountains, and the Ruwenzori otter shrew (Micropotamogale ruwenzorii, EN), one of only three representatives of the family Tenrecidae on the African mainland (the others are found only in Madagascar).
More than 30 of the nearly 200 mammals found in the Ethiopian Highlands are found nowhere else, including a remarkable six endemic genera, four of which are monotypic: three rodents (Megadendromus, Muriculus, and Nilopegamys) and one primate, the gelada (Theropithecus gelada). The Ethiopian wolf (Canis simensis, EN) is an endemic species found in the Afroalpine ecosystem of the Ethiopian Highlands; with less than 450 individuals in seven small and isolated populations, this wolf is the rarest canid in the world.
Nearly 350 reptile species are found in the Eastern Afromontane, of which more than 90 are endemic. The Eastern Arc Mountains and Southern Rift are home to more than 35 of these endemic species, including eight species of chameleons (six Chamaeleo and two Rhampholeon), three species of worm snakes (Typhlops), and six species of colubrid snakes. Most endemics are in the Eastern Arc Mountains, but Mount Mulanje in the Southern Rift has a number of species confined to it, including the Mulanje mountain chameleon (Bradypodion mulanjense) and Malawi stumptail chameleon (Rhampholeon platyceps).
About 14 percent of Africas reptile species live in the Albertine Rift, including about 15 endemic species. Five of these endemic species are chameleons, including the Rwenzori three-horned chameleon (Chamaeleo johnstoni), which looks like a miniature Triceratops and can grow to a length of 30 centimeters. The very rare strange-horned chameleon (Bradypodion xenorhinus) has a circular protuberance on the end of its nose and is confined to the Rwenzori Mountains, where it has been overcollected for the wildlife trade.
The hotspot is also home to about 230 amphibian species, nearly 70 of which are endemic. The Eastern Arc Mountains and Southern Rift are home to the genus Nectophrynoides, which includes the majority of the worlds viviparous (live-bearing) frogs. One of these species, the Kihansi spray toad (Nectophrynoides asperginis, CR) occurs only in a 2-hectare spray zone of the Kihansi Falls in the Udzungwa Mountains, although recent attempts to locate this species have been unsuccessful. New species are continually discovered throughout the region, including Churamiti maridadi (CR). This large, brightly colored tree toad belongs to a new genus, which was discovered in the Ukaguru Mountains in 2002.
The Albertine Rift is home to about 19 percent of Africas amphibian species, including more than 30 endemic species and three monotypic endemic genera: Parkers tree toad (Laurentophryne parkeri), the Itombwe golden frog (Chrysobatrachus cupreonitens), and African painted frog (Callixalus pictus, VU).
Six endemic genera of amphibians are found in the Ethiopian Highlands, four of which are monotypic (Altiphrynoides, Spinophrynoides, Balebreviceps, and Ericabatrachus), while the fifth, Paracassina, is represented by two frog species.
Including the Great Rift lakes in this hotspot area makes it a phenomenally important region for freshwater fish diversity and endemism, with more than 890 species of fish, nearly 620 of which are endemic. Lake Malawi is home to more than 380 fish species, nearly 90 percent of which are endemic. This includes an amazing diversity of cichlids and at least 12 large endemic catfishes of the genus Bathyclarias that live in deeper areas of the lake. Lake Tanganyika has more than 300 fish species, about 75 percent of which are endemic. In Lake Tana, which is the source of the Blue Nile in the Ethiopian Highlands, about a quarter of the nearly 65 fish species are endemic, including a loach Nemacheilus abyssinicus and 14 large cyprinid barbs.
While most invertebrates of the Eastern Afromontane are not well studied, the butterfly fauna is relatively well known. Up to 1,300 butterfly species may occur in the Albertine Rift alone, including nearly 120 endemic species and one endemic genus, Kumothales; nearly 80 species of butterfly are endemic to the Eastern Arc Mountains. The African giant swallowtail (Papilio antimachus), with a wingspan of 24 centimeters, is the continents largest butterfly. Three other large, conspicuous, but rare swallowtail butterflies (P. leucotaenia, P. ufipa, and Graphium gudenusi) are important symbols for conservation in the area.