in Sri Lanka - Ministry of Environment

Sri Lankan odonates because of lack of supporting evidence for their occurrence: Libellago indica(Hämäläinen et al., 2009) and Palpopleura s. sexmaculata (van der Poorten, 2011).DistributionThe biology of odonates is intimately tied to water and each species has a requirement for aspecific type of water (e.g. fast- or slow-flowing streams, stagnant water, marshland). In SriLanka, the majority of the common Oriental species are found at lowland tanks (reservoirs)in the dry zone (e.g. Ictinogomphus rapax, Crocothemis s. servilia). One species is restrictedto coastal areas (Macrodiplax cora). Several other common species are widespread in thewet lowlands and mid-hills, in marshes, streams and seeps (e.g. Orthetrum luzonicum).A few species are restricted to the higher elevations (e.g. Indothemis g. gracilis, Sympetrumfonscolombii). The endemics, however, tend to be localized to specialized habitats within thewet zone rainforest. These habitats can be compared to small islands; they often have highlyspecialized flora and fauna and it can be difficult for an individual to move to another habitat ifconditions become unfavorable. The habitat is fragile and easily disrupted. For example, the15 species of Drepanosticta are almost all found in very restricted habitats, usually small shadystreams within a forest patch. Two endemic species (Lyriothemis defonsekai and a yet-to-bedescribedspecies) are found only within a restricted area in the Sinharaja Forest Reservenear a heavily shaded, well-vegetated stream. Elattoneura leucostigma is found only in smallwell-vegetated streams in the dense montane forests. Several species of the Gomphidaefamily (e.g. Microgomphus wijaya) require well-shaded fast-flowing streams that have densevegetation on the edges. By contrast, Mortonagrion ceylonicum requires well-shaded scrubareas at the edge of still water or ditches.ThreatsDeforestation leading to disruption of the habitat and changes in water sources is probably themost pressing threat because a number of Sri Lanka’s endemic species (e.g. Drepanosticta,Platysticta, Libellago and members of the Gomphidae) are found in small patches of rainforest.Forests have been logged to extract timber, to allow for expansion of plantations and villagesand, in some areas, to maintain security during the conflict period. Cutting of the undergrowthby villagers for firewood produces changes in the habitat that impact unfavorably on the watersources on which the odonates rely. For example, the thinning of the forest at Dombagaskanda(Bodhinagala) has resulted in increased drying of the soils and streamlets between rains,adversely affecting the Platysticta species found there.Water pollution is also a serious threat. As a result of agricultural production, many chemicalsend up in the drains and streams where odonates breed. The increasing human populationalso puts pressure on water sources, causing increased extraction and use of water andincreased pollution from soap products and other human pollutants. This is detrimental to theodonates not only directly but also indirectly: other freshwater fauna which odonate larvae eatare also affected negatively. For example, at Balangoda, in the past 5 years, the stream hasbecome filled with soap and algae due to the increased human population. The Gomphids andMacromia that used to be seen here are no longer found.2