Channa ara ( Deraniyagala, 1945 )

Sudasinghe, Hiranya, Adamson, Eleanor A. S., Ranasinghe, R. H. Tharindu, Meegaskumbura, Madhava, Ikebe, Chiho & Britz, Ralf, 2020, Unexpected species diversity within Sri Lanka’s snakehead fishes of the Channa marulius group (Teleostei: Channidae), Zootaxa 4747 (1), pp. 113-132 : 116-119

Channa ara ( Deraniyagala, 1945)

(Figure 2,3)

Ophicephalus marulius ara: Deraniyagala, 1945: 95 ; Deraniyagala, 1952: 124 (in part)

Ophiocephalus marulius (not Hamilton, 1822): Day, 1878: 363 (in part); Day, 1889: 360 (in part)

Ophicephalus marulius: Deraniyagala, 1929: 83 (in part)

Channa marulius: Pethiyagoda, 1991: 279 (in part); Talwar & Jhingran, 1991: 1017 (in part); Courtenay & Williams, 2004: 83 (in part); Chaudhry, 2010 (in part); Kottelat, 2013: 461 (in part)

Channa ara: Pethiyagoda, 2006 (in part)

Diagnosis. Channa ara is distinguished from C. marulius , C. aurolineata and C. auroflammea by possessing fewer vertebrae (56 vs 59–63 in C. marulius ; 63–66 in C. aurolineata ; 58–61 in C. auroflammea ); fewer lateral-line scales (59–62 vs 62–65 in C. marulius ; 65–71 in C. aurolineata ; 61–65 in C. auroflammea ); fewer dorsal-fin rays (47–48 vs 50–56 in C. marulius ; 55–58 in C. aurolineata ; 52–54 in C. auroflammea ); and fewer anal-fin rays (29–30 vs 32–37 in C. marulius ; 35–38 in C. aurolineata ; 33–36 in C. auroflammea ). Further, C. ara can be distinguished from C. aurolineata and C. marulioides by white spots along mid-lateral blotches faint or absent (vs series of black scales rimmed in white along the mid-lateral dark blotches) in live adults. In comparison to South Indian C. pseudomarulius , C. ara possesses more vertebrae (56 vs 55); and more circumpeduncular scales (26–28 vs 24). Channa ara can be distinguished from C. cf. ara from the southwestern wet zone of Sri Lanka by having more circumpeduncular scales (26–28 vs 22–24); by the absence / faintness of the numerous large white spots along the mid-lateral dark blotches (vs. presence of spots in C. cf. ara ); and by bright orange colouration in between the mid-lateral series of dark brown blotches when live (vs white to yellow colouration) (see Figures 2–5 ).

Description. See Figures 2 and 3 for general appearance, and Tables 1 and 2 for morphometric and meristic data, respectively. Dorsal-fin rays 47 (1), or 48 (2). Anal-fin rays 29 (2), or 30 (1). Pectoral-fin rays 16. Lateral line scales 59 (1), 60 (1), or 62 (1) in total, 16 (1), 17 (1), or 18 (1) in pre-drop, 2 (1), or 3 (2) forming drop, 40 (1), or 41 (2) in post-drop. Predorsal scales 17 (2), or 18 (1). Scales above pre-drop 4.5 (2), or 5 (1), above post-drop 6.5 (1), 7 (1), or 7.5 (1), below post-drop 10 (2), or 11 (1). Circumpeduncular scales 26 (1) or 28 (2). Postorbital scales 10 (1), 11 (1), or 12 (1), with 7 (2), or 8 (1) scales in front of opercle; scales on opercle 3 (1), or 4 (2). Vertebrae 56 ( Fig. 6A ).

Colouration in preservative. Shortly after preservation, adults> 300 mm SL ( Figure 2 ) with head and body greyish dorsolaterally, white ventrally. Dorsal, anal, and caudal fins black with scattered white spots. Pectoral fin dark brown, pelvic fin white. Series of 4–6 large black blotches on mid-lateral body under dorsal fin, separated by bright orange blotches. White spots on body inconspicuous or absent. Orange blotches on body fading to white during long-term preservation.

Colouration in life. Juveniles of about 80–100 mm SL ( Fig. 3A ) dorsolaterally brown. A black band on side of body, originating at anterior margin of snout, extending to caudal-fin base and beyond, onto median rays of caudal fin. Light brown stripe extending from opercle to caudal-fin base, separating brown dorsal side and blackish ventral side of body. Head and body whitish cream ventrally. Caudal fin with an ocellus on dorsal half, formed by large black spherical spot rimmed by wide orange ring. Pectoral, pelvic and anal fins hyaline. Interradial membrane of dorsal fin with irregular pattern of black lines. Pupil outlined by yellowish orange rim, iris black with tinge of orange.

Adults> 500 mm SL ( Fig. 3B ) greyish black dorso-laterally. Black blotches on mid-lateral body, separated by bright orange blotches, extending as a ventro-lateral band along head and body. White spots on head and body absent or indistinct. Ocellus on caudal fin absent. Pupil outlined by yellowish orange rim, iris orange. Dorsal, anal and caudal fins black with white spots. Pectoral fin brownish black; rays of pelvic fin darker than in smaller specimens.

Habitat, distribution and natural history. Channa ara occurs primarily in the deep pools in the Mahaweli River and its tributaries. It has also been recorded from reservoirs in the Mahaweli catchment (Victoria and Randenigala: Fig. 1A ). In June 2014, the first author observed around 20 juveniles of ~ 80–100 mm SL in shallow water (~ 60–80 cm deep), among submerged roots, close to the bank, at the mouth of a stream draining into Badulu Oya of the Mahaweli basin, they were guarded by a pair of adults. The highest elevation from which we have recorded C. ara is at Kandy, about 500 m asl.

Molecular results. Three cox1 haplotypes were observed among Marulius group fishes collected in Sri Lanka, none of which have previously been observed in fishes collected in neighbouring continental regions. The three haplotypes correspond to Channa ara from the Mahaweli Basin (H1, n =4), C. cf. ara from the southwestern wet zone (H2, n =8), and C. marulius from the northern dry zone (H3, n =1). The relationship of Sri Lankan haplotypes to C. marulius haplotypes from continental regions ( India and Myanmar) is illustrated in Fig. 1B , with uncorrected pairwise genetic distances among all members of the Marulius group given in Table 3 .

The Channa ara cox 1 haplotype differs from all [ C. marulius + C. cf. ara ] haplotypes by a minimum of 22 mutations, and is indeed marginally more genetically similar to continental C. marulius (3.6–4.2%) and Sri Lankan C. cf. ara (3.7%) than to Sri Lankan C. marulius (4.6%), albeit the latter was only represented by a small sample size. The Sri Lankan C. marulius differs from continental C. marulius by 1.6–2.3%, doubling the known intraspecific genetic divergence at cox1 that was previously observed across this species’ large continental geographical distribution encompassing India and western Myanmar. In contrast, the Sri Lankan C. cf. ara differs less from continental C. marulius (uncorrected pairwise genetic distance of 1.0–1.6%) than it does from the C. marulius that occurs on the same island, in Sri Lanka’s northern dry zone (2.0%).

With the exceptions of Channa marulius and C. cf. ara , C. ara differs from all other species in the Marulius group by a minimum of 8% uncorrected pairwise genetic distance for cox1 ( Table 3 ).

Figures

FIGURE 1. A, Map of Sri Lanka showing geographical origin of samples of the Marulius group used in this study. Specimens referred to as ‘not collected’ were observed in the wild but not included in the molecular or morphological analyses. The black lines represent drainage margins; B, median-joining haplotype network for the Marulius group in Sri Lanka is based on the analysis of a 654 bp fragment of the cox1 gene. The areas of the circles are proportional to the number of individuals sharing a given haplotype. The number of mutational steps>1 is indicated in parentheses. Black circles are hypothetical nodes. Legend colours correspond to the region or species.

FIGURE 2. Colouration of Channa ara shortly after preservation. A, adult, 2020.02.01.NH, neotype, 300 mm SL, Angammedilla, Mahaweli River; B, large adult, UPZM uncatalogued, 650 mm SL, Victoria Reservoir, Mahaweli River. C, Deraniyagala’s (1952: plate 19) illustration of Ophicephalus marulius ara.

FIGURE 3. Live colouration of Channa ara. A, juvenile, ~80 mm SL, Badulu Oya, Mahaweli River; B, large adult, ~650 mm SL, Victoria Reservoir, Mahaweli River, photo courtesy of Kumudu Wijesooriya.

FIGURE 4. Colouration of Channa cf. ara in preservation. A, small juvenile, DZ 5269B, 46.5 mm SL, Kelani River; B, large juvenile, ZRC 22484, 81.6 mm SL, Bentara River, photo courtesy of Tan Heok Hui; C, subadult, DZ 4330, 230 mm SL, Bentara River; D, adult, DZ 4010, 380 mm SL, Gin River.

FIGURE 5. Colouration of Channa cf. ara in life. A, small juvenile, ~55 mm SL, Kelani River; B, large juvenile, ~100 mm SL, Kelani River; C, sub-adult. ~200 mm SL, Kelani River; D, adult, ~300 mm SL, Gin River; E, large adult, ~650 mm SL, Bentara River.

FIGURE 6. X-radiographs of members of the Marulius group in Sri Lanka. A, Channa ara, 2020.02.01.NH, neotype, 300 mm SL, Angammedilla, Mahaweli River; B, C. marulius, DZ 4900, 350 mm SL, Rajanganaya, Kala Oya; C, C. cf. ara, DZ 4330, 230 mm SL, Lewwanduwa, Bentara River.