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Thewildlife of Sri Lanka includes itsflora andfauna and their naturalhabitats.Sri Lanka has one of the highest rates of biologicalendemism (16% of thefauna and 23% of flowering plants are endemic[1]).
The mountains and the southwestern part of the country, known as the "wet zone", receive ample rainfall (an annual average of 2500 millimeters). Most of the southeast, east, and northern parts of the country comprise the "dry zone", which receives between 1200 and 1900 mm of rain annually.
The most recent update on the Sri Lankan biodiversity was the 6th National Report of theConvention on Biological Diversity. This report provided an updated list of species as of the end 2018. However, in 2019, 54 new species were described: including 26 spiders, (14 cellar spiders, 7 jumping spiders, 4 crab spiders and 1 tarantula), 1 scorpion species, 5 mites and ticks, 14 reptiles (13 day geckos and 1 snake), 1 shrub frog, 1 orchid and 6 lichens. Later in 2021, Professors Devaka Weerakoon and Amila Sumanapala released an updated list of taxa as of the end of 2020.[3][4]
| Group | Class | No. of species | Endemic species | Endemism |
|---|---|---|---|---|
| Vertebrates | Mammalia | 135 | 19 | 16.8% |
| Aves | 515 | 34 | 11.89% | |
| Reptilia | 243 | 158 | 65.33% | |
| Amphibia | 120 | 107 | 91.66% | |
| Freshwater fish | 124 | 58 | 53.76% | |
| Marine fish | 1,387 | 0 | 0% | |
| Invertebrates | Gastropoda | 5246 | ||
| Insecta | 11,144 | |||
| Araneae | 383 | 271 | 70.75% | |
| Scorpiones | 18 | 7 | 38.88% | |
| Crustacea | 51 | 51 | 100% | |
| Echinodermata | 76 | 1 | 100% | |
| Plants | Angiosperms | 3,120 | 904 | 16.8% |
| Bryophyta | 575 | 0 | 0% | |
| Pteridophyta andLycophyta | 390+ | 47 | 100% | |
| Jungermanniales | 296 | 0 | 0% |
Sri Lanka is home to roughly 123species ofmammals, 41 of which are threatened (9 critically). 16 of the species are endemic, of which 14 are threatened,[5] including the largesloth bear, the endemicSri Lanka leopard, theSri Lankan elephant and thesambar.Bats have the highest amount of species (out of 200 mammalianorders), with 30 species. Sri Lanka's surrounding waters are home to 28 species ofCetaceans.
Sri Lanka currently contains 185 species ofreptiles, of which 60 are threatened and 115 are endemic. Most of the reptiles aresnakes and the largest two are themugger crocodile andsaltwater crocodile.[5]
Flooding has led to increased human-crocodile conflict around theNilwala River, with crocodiles often becoming trapped as floodwaters recede. Such floods are becoming exacerbated byclimate change.[6]
Sri Lanka has one of the richest diversity ofamphibians in the world, containing 122 species of amphibians up to January 2019 with many recent discoveries, with 112 endemic species.[5]
Sri Lanka is home to 227 species of birds (though some past estimates put it as high as 486[7]), 46 of which are threatened (10 critically).[5]
Sri Lanka contains 93 species offreshwater fish, of which 50 are endemic. 28 species are categorized as threatened by theIUCN.[5] There are 8 species of brackish water fish that also come to freshwater, and 24 introduced exotic fish species.
Insects belonging to all 32 orders exceptGrylloblattodea have been recorded from Sri Lanka.
Coleoptera, which is the largest order of insects, is the largest in Sri Lanka with 3,033 documented species.[8] Lepidopterans,moths and butterflies, have the second largest number of species in Sri Lanka. 245 butterflies species are recorded, of which 24 are endemic to the island. 1695 species of moths are also found, but the endemism is unknown.
Hymenopterans, which includes ants,bees,wasps contribute to the third largest insect order in Sri Lanka. Sri Lanka is home to 181 species ofants that included to 61 genera and 10 subfamilies. One endemic genusAneuretus is also included to the list. There are about 70,000 species of bees of orderHymenoptera in the world with nearly 450 genera and 7 families. Out of them, Sri Lanka comprises 148 species in 38 genera and 4 families.
True flies andmosquitoes belong to the orderDiptera, of which there are many in Sri Lanka. There are more than 1,341 dipterans found in the island, which makes it the fourth largest insect order.[8] About 131 species ofmosquitoes, in 16 genera, are described. Though they are primary vectors of many human diseases, the majority of mosquitoes in Sri Lanka are harmless to humans and livestock.
The exact species for other orders is still not classified and documented. Walker in 1861, listed 2,007 species belongs to 9 orders and Haly on 1890 identified 1,510 beetle species from Sri Lanka. However, after many publications from many foreign entomologists, two Sri Lankan entomologists, Anura Wijesekara and D. P. Wijesinghe documented 11,144 insect species belongs to 30 orders from Sri Lanka in 2003.[9][8]
Damselflies are categorized in suborderZygoptera anddragonflies are in suborderAnisoptera. There are 121 species within 13 families in Sri Lanka. 59 species are endemic. Hubbard and co-workers documented 46 species in 8 families of orderEphemeroptera. Henneman in 2002 recorded 69 species in orderOrthoptera. He also collected few specimen of orderPhasmatodea around central hills. 66 species of orderBlattodea are found, but not taxonomic evidences. Few species of the orderMantodea were studied by Henry in 1931. Clear documentation of the species withinDermaptera can be found, which was initiated by Burr (1901) and Brindle (1972). Within thetermite infraorderIsoptera, 56 species are recorded. In 1913, Green compiled a concise catalogue for termites in Sri Lanka.[8]
Only 4 species of orderEmbioptera are recorded. In the orderPsocoptera, two subfamilies,Epipsocidae andPseudocaeciliidae have been studied. Information about species of the ordersThysanoptera,Neuroptera,Mecoptera, andSiphonaptera is very thin and more studies are required. Only the familyConiopterygidae of Neuroptera has been studied in 1982.[8]
Sri Lanka is known to be home to 794 species ofHemipterans. Detailed work of Sri Lankan hemipterans are recorded in the bookCatalogue of Hemiptera of Sri Lanka. Sri Lanka comprises 74 species in 46 genera and 6 families ofaphids within the orderHemiptera. 2 endemic aphid species are found on Sri Lanka. Checklists on ordersTrichoptera andStrepsiptera exist, but more recent work is needed.[8]
All 51 species along with 5 genera in the familyGecarcinucidae are endemic to Sri Lanka. 98% of those crabs are IUCN categorized as threatened, endangered or critically endangered.
Isopods occur abundantly in the sea, freshwater and land. They typically flattened dorsoventrally and mostly scavengers. Sri Lanka harbors 92 species of isopods of 53 genera in 23 families.
The exact number of species around mangroves and estuaries within coastal marine regions is not clear, but during research on diversity of mangrove crabs in Kadolkele,Negombo, five species were identified, with two new species.[10] Most marine crabs are much larger and are often caught in fishing nets. They are edible with high protein. Some of marine edible crabs from Sri Lanka are:[11]
There are over 246 land gastropods of Sri Lanka, of which 83% are endemic. Sub classPulmonata consists of 159 species within 23 families and subclassProsobranchia by 88 species in four families. Five land snail genera,Ravana,Ratnadvipia,Acavus,Oligospira andAulopoma are endemic to Sri Lanka with 14 species in them.[12][13] Thirteen more genera such asRuthvenia,Thysanota,Cryptozona,Euplecta,Mariaella,Eurychlamys,Corilla,Beddomea,Trachia,Leptopomoides,Micraulax,Tortulosa andNicida are only in theWestern Ghats of India and Sri Lanka. 18 species are recorded as exotic species and agricultural pests.
Fauna of Sri Lanka also includefreshwater snails. The number of marine molluscs of Sri Lanka is not known, though there were about 240 species listed in 2006.[14]
The diversity of subphylumMyriapoda, is not well studied in Sri Lanka. The facts and checklists of these creatures date back to Newport in 1845, which is the first known study aboutcentipedes. Many centipede works are more than a century old.[15]Millipede diversity is much better studied. Currently, 104 species of millipedes and 19 species of centipedes are known from Sri Lanka.[16]
The detailed work on Sri Lankan spiders was through theChecklist of Spiders of South Asia Including 2006 Revision of Indian Spider Checklist by Manju Siliwal and Sanjay Molur. This checklist provided all the described spider species of South Asia and part of South-East Asia as well.[17]
According to this checklist, Sri Lanka has 501 species of spiders belonging to 45 families and 213 genera. Out of these, 250 are endemic with 22 endemic genera.[8]
Spiders in genusMyrmarachne are commonly called ant-mimicking spiders. They are grouped in the familySalticidae of orderAraneae. Out of more than 100 species described, 12 are found in Sri Lanka. Three species were described in 2015.
There are 8 species of tarantula that have been recorded in Sri Lanka. When considering with theIndian subcontinent, 15 species ofPoecilotheria are recorded from both countries; 7 endemics fromIndia and 7 endemics fromSri Lanka. 1 species is found in both countries.
There are 18 species of scorpions in Sri Lanka. Out of these 18, 7 are endemic. In addition, 4 subspecies of the 9 non-endemic species are also endemic to Sri Lanka.
According to 2014 research, 47 species of pseudoscorpions have been identified in Sri Lanka. Out of this 43 species, 20 species are endemic to Sri Lanka.
The diversity of lesser arachnids within Sri Lanka is not extensive. Some observations on particular species have been undertaken by some local and foreign scientists. According to them, there are 3 species ofwhip spiders, 4 species ofwhip scorpions, and 21 species ofdaddy longlegs found in Sri Lanka.
Ticks belong to superfamilyIxodoidea of the orderParasitiformes. 27 species of ixodid ticks, commonly called hard ticks, of the familyIxodidae belonging to 9 genera have been reported from Sri Lanka.
Echinoderms belong to the phylumEchinodermata. They aredeuterostomes that are closely related tochordates. In Sri Lanka, there are 39 regular echinoids belonging to 28 genera, 9 families, and 5 orders.[18] Besides, there are 21 irregular echinoid species belonging to 4 orders, 9 families and 15 genera in Sri Lanka.[19]
Diversity andendemism of plants in Sri Lanka are quite high.[20] There are 3,210flowering plants belonging to 1,052 genera. 916 species and 18 genera are endemic to the island. Additionally, all but one of the island's more than 55dipterocarps are confined to Sri Lanka. Although not lately assessed, Sri Lanka'sferns are estimated at 350 species. Diversity, richness, and endemism across alltaxa groups are much higher in thewet zone than in the dry zone. Wet zone, which accounts for only a quarter of Sri Lanka's land area, harbours 88 percent of the flowering plants, and 95 percent of country's flowering plant endemics. The natural forests of Sri Lanka are categorized into eight types.[21]
Loxococcus, a monotypic genus consisting of the sole speciesLoxococcus rupicola, is the only palm (Arecaceae) genus that is endemic to Sri Lanka.[22] A newGesneriaceae speciesHenckelia wijesundarae, endemic to Hiniduma,Galle, was described and illustrated in 2016 by Subhani Ranasinghe et al.[23]
In 2020, a species of orchidGastrodia gunatillekeorum was described from Sinharaja.[24] In the same year, several other plants were first described: one species of seagrass:Halophila major and six species of liverworts;Lejeunea sordida,Leptolejeunea subdentata,Spruceanthus polymorphus,Frullania udarii,Heteroscyphus turgidus andFuscocephaloziopsis lunulifolia. With that, the total number of leafy liverwort species in Sri Lanka increased to 296 in 63 genera. In the meantime, a species of fungus,Helvella crispa, was also identified from Sri Lanka.[4]
Sri Lankan environmentalist, Dr.Gothamie Weerakoon has discovered 51 new varieties oflichens endemic to Sri Lanka, of which 8 were found in theKnuckles Mountain Range.[25][26] While Dr. Udeni Jayalal et al. found 2 new lichens from theHorton Plains in 2012,Anzia mahaeliyensis andAnzia flavotenuis.[27] Currently, more than 400 species of lichens are found in Sri Lanka.
