Unexpected species diversity within Sri Lanka’s snakehead fishes of the Channa marulius group (Teleostei: Channidae)

Abstract

The taxonomic status of the large snakeheads of the Channa marulius group that occur in Sri Lanka is reviewed and clarified. Two species are recognized from the island, based on both morphological and molecular (cytochrome c oxidase subunit 1: cox1) differentiation: C. marulius Hamilton from the northern dry zone and C. ara Deraniyagala from the middle and lower regions of the Mahaweli basin. Channa ara is endemic to Sri Lanka and can be distinguished from its Marulius group congeners, C. marulius, C. aurolineata and C. auroflammea, by having fewer dorsal- and anal-fin rays, fewer lateral-line scales and fewer vertebrae; from C. marulioides by a different adult colour pattern; and from C. pseudomarulius by having more vertebrae. At the cox1 barcoding locus, Channa ara is at least 3.6% genetically different from C. marulius, and at least 8% different from the other described species in the group. Specimens collected from the southwestern wet zone in Sri Lanka are a puzzling third component of the Marulius group’s diversity, uncovered in this study, and identified here as C. cf. ara. Whilst genetically more similar to C. marulius, C. cf. ara possesses fewer dorsal- and anal-fin rays, fewer lateral-line scales and fewer vertebrae and is therefore morphologically more similar to C. ara. Channa ara can be distinguished from C. cf. ara, however, by differences in circumpeduncular scale count, adult colour pattern, and by an uncorrected pairwise genetic distance of 3.7% in cox1 sequences. A neotype is designated for Ophicephalus marulius ara Deraniyagala.

Snakeheads of Sri Lanka: A Taxonomic and Biogeographic Review

“…In current taxonomic treatments Ophicephalus Bloch 1793 is considered as a synonym of Channa (Pethiyagoda, 1991;Kotteilat, 2013). According to the current and historically published literature on freshwater fishes of Sri Lanka including Gunther (1861), Duncker (1912), Deraniyagala (1929Deraniyagala ( , 1932Deraniyagala ( , 1945Deraniyagala ( , 1952Deraniyagala ( , 1963, Munro (1955), Mendis and Fernando (1962), Senanayake (1980), Pethiyagoda (1991), Goonatilake (2012), De Silva et al, (2015), Goonatilake et al, (2020), and Sudasinghe et al, (2020a) and Sudasinghe et al, (2020b) the genus Channa is represented in Sri Lanka by six valid species viz. Channa ara (Deraniyagala, 1945), Channa marulius (Hamilton, 1822), Channa kelaartii (Gunther,1861), Channa orientalis Bloch and Schneider 1801, Channa punctata (Bloch, 1794) and Channa striata (Bloch, 1793).…”

“…Channa ara (Deraniyagala, 1945), Channa marulius (Hamilton, 1822), Channa kelaartii (Gunther,1861), Channa orientalis Bloch and Schneider 1801, Channa punctata (Bloch, 1794) and Channa striata (Bloch, 1793). According to the recent national literature on Sri Lankan Channidae (Goonatilake, 2007, De Silva et al, 2015, Goonatilake et al, 2020, Sudasinghe et al, 2020a, two species of snakeheads, Channa ara, and C. orientalis, are considered as endemic to the island.…”

“…Channa striata) and aquarium trade (C. marulius and C. orientalis) (Willey, (1910;Pethiyagoda, 1994;Amarasinghe et al, 2006;De Silva et al, 2015). Although these six species have currently been accepted in the Sri Lankan publications of freshwater fishes (Goonatilake, 2012;Goonatilake et al, 2020;Sudasinghe et al, 2020a;Sudasinghe et al, 2020b), the need for a taxonomic reassessment of the genus in Sri Lanka is discussed in this paper.…”

“…They are characterized by peculiar morphological features, such as an elongated cylindrical body, long and entirely soft-rayed dorsal and anal fins, a large mouth with well-developed teeth on both upper and lower jaws, vomer and palatine bones of the skull, and an accessory air-breathing apparatus known as the suprabranchial organ, as it is situated in the suprabranchial cavity in the head (Talwar and Jhingran, 1991;Jayaram, 1999). The snakeheads (Actinopterygii: Perciformes: Channidae) comprise more than 40 valid species in three genera; Channa, Parachanna and Aenigmachanna (Li et al, 2006;Serrao et al, 2014;Britze et al, 2019;Praveenraj et al, 2019;Sudasinghe et al, 2020a). Snakeheads of the genus Channa are distributed mainly in tropical Asia, and Parachanna in tropical Africa, while Aenigmachanna with only a single species recorded from South India (Li et al, 2006;Britze et al, 2019).…”

“…In Sri Lanka, the Family Channidae is represented only by the genus Channa Scopoli, 1777. Willey (1909), Duncker (1912), Deraniyagala (1929Deraniyagala ( , 1932Deraniyagala ( , 1945Deraniyagala ( , 1952Deraniyagala ( , 1963, Mendis and Fernando (1962), Senanayake (1980), Pethiyagoda (1991), De Silva et al, (2015), and Sudasinghe et al, (2020a), Sudasinghe et al, (2020b) have provided accounts of ecology, distribution and the taxonomic status of the family Channiade in Sri Lanka. All six species of this genus, are native to Sri Lanka, namely, Channa ara (Sri Lanka giant snakehead), Channa marulius (giant snakehead), Channa striata (murrel), Channa orientalis (Sri Lanka smooth-breasted snakehead), Channa punctata (spotted snakehead), and Channa kellarti (brown snakehead).…”