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A total of 61 endemic species were assessed. Of these, 12 point endemic species were listed as Critically Endangered (CR); 24 range-restricted species were Endangered (EN); and nine species were Vulnerable (VU). In addition, five species were Near Threatened (NT); two were listed as Data Deficient (DD); and the remaining were listed as Least Concern (LC). This means that 74% — nearly three quarters — of the freshwater fish endemic to Sri Lanka were found to be Threatened with extinction. Thirty-six native species were also assessed and of these, only eight species were listed as Threatened.
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Kelani River is the fourth longest river in the South-Asian island, Sri Lanka. It originates from the central hills and flows through a diverse array of landscapes, including some of the most urbanized regions and intensive land uses. Kelani River suffers a multitude of environmental issues: illegal water diversions and extractions, impoundment for hydroelectricity generation, and pollution, mostly from agrochemicals, urban runoff, industrial discharges, and domestic waste. Moreover, loss of riparian forest cover, sand-mining, and unplanned development in floodplains have accentuated the environmental damage. In this study, based on Kelani River basin, we reviewed the status of biodiversity, threats encountered, conservation challenges, and provided guidance for science-based conservation planning. Kelani River basin is high in biodiversity and endemism, which includes 60 freshwater fish species of which 30 are endemic. Urbanization related threats are more severe in the middle and lower reaches while agriculture and impoundments peril the river in upper reaches. Documentation of these threats can be dated back to 1980, yet, Sri Lankan government has failed to take substantial actions for sustainable management of Kelani River basin, despite the presence of nearly 50 legislations pertaining to water and land management. Given high biodiversity richness, human dependency, and evident ecological deterioration, Kelani River basin should be prioritized for biodiversity conservation and sustainable resource management. Conservation and wise use of freshwater resources is a global concern, particularly for developing nations in Asia. Therefore, our review and guidance for scientifically informed conservation would serve as a prototype for basin-wide river management for Sri Lanka as well as for other developing nations of tropical Asia.
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River Mahaweli in Sri Lanka was greatly altered by dams under the Mahaweli diversion Scheme. Fish assemblages in segments of five tributaries of Mahaweli; Badulu Oya, upstream of Ulhitiya Oya and Loggal Oya (unregulated streams) and, Minipe and downstream of Ulhitiya Oya (regulated streams) were compared. Sampling was carried out in three selected 100 m segments from each study stream using hand nets, drag nets and cast nets. 40 fish species in 10 families were recorded. Ulihitiya downstream recorded the lowest abundance and species richness. Unregulated streams demonstrated a higher proportion of endemics (Dry: 41-54% and Wet: 50-60%) while regulated streams had highest proportions of exotics in both seasons (Dry; 26 and 72 %; Wet: 34 and 66 % in Minipe and Ulhitiya downstream, respectively). The results suggest that native and endemic fishes are more sensitive to altered habitat conditions highlighting the importance of protecting the remaining natural habitats.
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A recent (2013) taxonomic review of the freshwater-fish genus Rasboroides, which is endemic to Sri Lanka, showed it to comprise four species: R. vaterifloris, R. nigro- marginatus, R. pallidus and R. rohani. Here, using an integrative-taxonomic analysis of morphometry, meristics and mitochondrial DNA sequences of cytochrome b (cytb) and cytochrome oxidase subunit 1 (coi), we show that R. nigromarginatus is a synonym of R. vaterifloris, and that R. rohani is a synonym of R. pallidus. The creation and recognition of unnecessary taxa (‘taxonomic inflation’) was in this case a result of selective sampling confounded by a disregard of allometry. The population referred to R. rohani in the Walawe river basin represents an undocumented trans-basin translocation of R. pallidus, and a translocation into the Mahaweli river of R. vaterifloris, documented to have occurred ca 1980, in fact involves R. pallidus. A shared haplotype suggests the latter introduction was likely made from the Bentara river basin and not from the Kelani, as claimed. To stabilize the taxonomy of these fishes, the two valid species, R. vaterifloris and R. pallidus, are diagnosed and redescribed, and their distributions delineated. We draw attention to the wasteful diversion of conservation resources to populations resulting from undocumented translocations and to taxa resulting from taxonomic inflation. We argue against translocations except where mandated by a conservation emergency, and even then, only when supported by accurate documentation.
Article
The endemic Sri Lankan synbranchid 'Monopterus' desilvai is redescribed based on additional material. In life, individuals have a maroon background colour with numerous dark brown blotches. They breathe air, which is stored in paired suprabranchial pouches. The head skeleton of M. desilvai is described in detail. This species shares with M. cuchia, M. indicus, M. fossorius, M. ichthyophoides, M. rongsaw, M. luticolus, and M. boueti derived and unique modifications of the gill arch skeleton: ceratobranchial 1 is spatially removed from hypobranchial 1 and aligned with hypo-and ceratobranchial 2, leading to a separation of the anterior from the posterior gill arch skeleton. It shares with M. cuchia, M. indicus, M. fossorius, and M. ichthyophoides an even further derived gill arch skeleton, in which epibranchial 1, the interarcual bone and pharyngobranchial 2 are absent, modifications puta-tively related to the evolution of paired suprabranchial pouches in these species. Based on these shared derived characters the group comprising M. cuchia, M. indicus, M. fossorius, M. ichthyophoides and M. desilvai, is recognized as a monophyletic unit for which the oldest available generic name is Ophichthys Swainson.
Article
Molecular and morphological analyses show that Esomus thermoicos is the only species of Esomus in Sri Lanka. Esomus thermoicos is distinguished from its congeners by the combination of having a complete lateral line, a dark mediolateral stripe, a short pectoral fin that does not reach the anal-fin origin when adpressed, and by lacking conspicuous spots or blotches on the body. A limited series of specimens from southern peninsular India are also identified as E. thermoicos. Esomus brevibarbartus is a junior subjective synonym of E. thermoicos.
Article
The Sri Lankan population of the spiny eel previously assigned to Macrognathus aral Schneider (Teleostei: Mastacembelidae) is shown to be a distinct species, for which the name M. pentophthalmos Gronow is available. Macrognathus pentophthalmos is distinguished from its closest congener, M. aral, by having 14–16 dorsal spines and a pre-dorsal length of 43.3–46.8% of standard length (SL) (vs. dorsal spines 18–22 and pre-dorsal length 35.5–40.8% SL in M. aral). Macrognathus pentophthalmos differs from its only other Indian congener, M. guentheri Day, among other characters, by having 24 pairs of rostral tooth plates (vs. rostral tooth plates absent). With the present designation of a neotype, Rhynchobdella orientalis Bloch & Schneider (type locality East Indies to Sri Lanka) becomes an objective junior synonym of M. aculeatus Bloch. Although assessed as ‘common’ in 1980, the population of M. pentophthalmos suffered a precipitous decline in the following decade, the causes of which are unknown. The species may now be extinct.
Article
Since its first record from the island in 1912, the barb Puntius amphibius Valenciennes has regularly featured in Sri Lanka’s ichthyofaunal inventories. Recent work has shown, however, that the name P. amphibius should be reserved for a species originally collected from Bombay, India, and described by Achille Valenciennes in 1842, now known only from its lectotype. The Sri Lankan fish hitherto known by this name is an undescribed species. Puntius kamalika, new species, is distinguished from all Sri Lankan and peninsular-Indian congeners by having (in addition to a suite of mensural characters) ½4/1/2½ scales in transverse line between mid-dorsal scale row and pelvic-fin origin and lacking any prominent markings on fins and body in both living and preserved examples. The new species is widely distributed in the island’s wet-zone lowlands (rainfall > 2,500 mm yr -1 ), where it occurs in streams, rivers and marshes between the Kelani-River basin draining to the island’s west, and the Gin River basin to the south. It is locally common.
Article
We address several problems arising from 'A review of the genus Devario in Sri Lanka (Teleostei: Cyprinidae), with description of two new species', a paper authored by S. Batuwita, M. de Silva and S. Udugampola and published in 2017 in the journal FishTaxa (2(3): 156-179). The neotypes they designate for Perilampus malabaricus Jerdon and Perilampus mysoricus Jerdon are inconsistent with article 75.3 of the International Code of Zoological Nomenclature ('the Code') and are hence invalid. Devario udenii, which they describe as a new species, is shown to be indistinguishable from D. microne-ma sensu Batuwita et al. The characters by which they distinguish another new species, D. annnataliae, are shown to be self-contradictory, making it impossible to distinguish from its congeners; it is treated as a species inquirendum. The diagnoses provided for D. malabaricus, D. micronema and D. monticola are ambiguous and self-contradictory, rendering them unusable. Much of the material examined, stated to be in the collection of the National Museum of Sri Lanka, is not deposited in that institution: such material as is deposited is inconsistent with the specimen data published by Batuwita et al.