Fauna. – Madagascar, from the zoogeographical point of view, has often been considered as a sub-region of the Ethiopian region, together with the Comoros, the Seychelles, the Reunion, Mauritius and other smaller islands. However, it deserves to form a region of its own.
Despite the proximity to the African continent, the Malagasy fauna is profoundly different from the Ethiopian one: it lacks numerous species and entire systematic groups extraordinarily widespread throughout the Ethiopian region and well represented in Mozambique, while it possesses many characteristic species, not a few exclusive groups., and others that it has in common with continents other than the African. Certainly there is no lack of faunal resemblances between Madagascar and East Africa, just as there is no lack of them between Madagascar and India; but the dissimilarities with respect to any other region are so profound that the island shows a real faunal individuality. And, if on the one hand several biogeographers argue that the Malagasy fauna was formed at the expense of African and Indian elements, others reasonably believe that terrestrial life developed autonomously on that island. Cuénot declares that the history of Madagascar’s animal population is one of the most difficult enigmas of zoogeography.
Almost half of Malagasy mammal species belong to the Lemurid family. Madagascar is currently the kingdom of these prosimians, so much so that out of just over sixty species of living Lemurids, as many as thirty-five are confined to this large island, where they form the exclusive subfamily of Lemurinae. Also the Aje – aje (Chiromys madagascariensis), another prosimian, the only representative of the Chiromyidae family, is an exclusively Malagasy species.
According to CACHEDHEALTH, the island has only nine species of Carnivores, all of the viverrids group: very characteristic are the Cryptoprocta ferox and the Fossa fossa. Of large herbivores, nothing else can be pointed out than a sort of wild boar, the Potamochoerus larvatus, similar to the African potamocheri; but in the Quaternary there were also small hippos.
Madagascar’s own insectivores are the centetidae, with eighteen species, to which belongs the well-known and characteristic Tanrec (Centetes ecaudatus) with its back bristling with quills. Another particular insectivore is the Geogale, which finds its relatives only in the Potamogale of Guinea. Among the rodents there are some noteworthy mice that constitute a subfamily (Nesomyinae) exclusive to Madagascar.
The Malagasy ornithofauna is very rich, with families of birds exclusive to the island, such as that of the Vangidae with 13 species, that of the Acrocharidae with only one species, that of the Philepittidae with two species, that of the Leptosomatiaae with two species (one of which however it lives in the Comoros) , that of the Mesoenatidae with the only variegated Mesoenas species, whose affinities are to be found in the Kagu (Rhinochetusjubatus) of New Caledonia. The gigantic Aepyornis, now extinct, find their kindred in the Dinornis of New Zealand. The island has passerines, waders, birds of prey, palmipeds, etc. Noteworthy are the parrots called vasa.
Special reptiles of the island are the Uroplatidae, a kind of gecko. Chameleons abound there: nearly half of the living species in this group are Malagasy. Lizards and vipers are missing. The presence in Madagascar of basically South American reptiles is strange: the island in fact has two species of boa snakes and one of Corallus, as well as six species of iguanids.
There is scarcity of Amphibî. Salamanders, newts and in general all Urodeles are absent. Toads, almost cosmopolitan, are missing. But there are frogs and other anurans among which eight species of Mantella and two of Stumpffia are characteristic. Mainly Malagasy are the Discopidae, which are then only found in Indochina and Borneo.
Freshwater fish are scarce and generally not very characteristic.
The terrestrial snails of the Helicidae family are numerous, indeed their abundance contrasts with the poverty found in intertropical Africa. Among the freshwater bivalve molluscs, the Unio are missing, which, with the exception of Celebes and Haiti, are widespread all over the world.
Among the freshwater crabs, the Hydrothelphusa, exclusive to the island, is noteworthy ; river shrimps, completely absent in the African continent, are confined to the eastern side of Madagascar and belong to the genus Astacoides, typical of the island.
Richly represented are the insects. Butterflies, with the exception of uranias, are perhaps the least interesting; but the beetles are abundant and with numerous characteristic genera, among which several longicorns must be pointed out.
Flora. – The flora of Madagascar constitutes a special domain of the paleotropic kingdom. Nell’isola forests occupy an area of less than 70,000 sq. Km, which is less than 1 / 10 of the total area. The most wooded region is the eastern side, where the so-called eastern forest is interspersed with large areas covered with herbaceous vegetation. The forest contains, mixed, hundreds of different essences but almost all slow growing and persistent leaves that do not give organic contributions to the poor soil. Changes in the appearance and constitution of the forest can be seen moving from east to west. In the eastern coastal area there are various species of palmizî, Copaifera, Afzelia bijuga, Canarium, Terminalia catappa, Brehmia speciosa, etc. In the middle zone, ebony and rosewood abound. The coastal and middle zone, from sea level up to 600 m. above sea level, it was partially cleared artificially by setting it on fire; but now deforestation is prohibited. The cleared areas have only herbaceous vegetation. The upper area, on the other hand, is still rich in forests and in it, much more than in the lower and middle areas, precious essences abound among bamboos, tree ferns, lianas, epiphytes, and among these notable are two species of orchids well known to floriculturists: Angraecum superbum and Ang. sesquipedale, very popular in Europe because they bloom in different seasons from those of Brazil, which are the most widespread on the markets of the old continent.
In the western region there are also some forests parallel to the coast, but they are less dense than the eastern ones. The west coast has a band of paletuvieri that surround the bays and estuaries; along the dunes, among the scattered scrub, Malagasy tamarinds and plums rise. Beyond the dunes are fairly dense forests in which baobabs and tamarinds predominate, which represent elements of connection with the Sudanese flora together with the papyri found in watercourses and the genus Hydrostachis ; ebony (Diospyros leucomela and D. perrieri), Rosewood (Dalbergia of different species), sandalwood (Santalina madagascariensis) and numerous vines of the genus Landolphia who produce rubber. Finally, on the western slope of the Bemaraha, the great forest of Antsingy stretches with ebony and Canariums of different species. This forest has essences that, for the most part, are not found in the eastern region. The central part of the island is, for the most part, very poor in trees.
The southern extremity of Madagascar has a particular vegetation, formed by xerophilous plants: arborescent or cactiform Euphorbiacee, Didieraceae, Apocinaceae (Pachypodium), etc. In this region, plants with persistent leaves, such as tamarinds, etc., are found only at the bottom of the valleys. The most characteristic plant of the island’s vegetation is, as mentioned, the Ravenala madagascariensis (see traveler’s tree). In addition, the island has a family of endemic plants, the Chlaeneaceae with 22 species: some floristic elements belong to the Monsoon region (Nepenthes), others (Phílippia, Aristea, Streptocarpus) to South African vegetation.