Channa auroflammea, Adamson & Britz & Lieng, 2019

Adamson, Eleanor A. S., Britz, Ralf & Lieng, Sopha, 2019, Channa auroflammea, a new species of snakehead fish of the Marulius group from the Mekong River in Laos and Cambodia (Teleostei: Channidae), Zootaxa 4571 (3), pp. 398-408 : 400-403

Channa auroflammea , new species

Figures 2–3 , 5D

Holotype. BMNH 2015.1 .29.13, 600 mm SL; Cambodia: Ban Lung market, reportedly collected at Lumphat, Mekong; E. Adamson et al. 10 July 2013

Paratypes. BMNH 2015.1 .29.14, 454 mm SL; same data as holotype . BMNH 1980.12.16.22-23, 2, 208- 210 mm SL; Laos: Vientiane fish market, Mekong; A. Davidson, collection date unknown . BMNH 2018.12 .24.1, 300 mm SL; Cambodia: Stung Treng market, Mekong ; E. Adamson et al., 0 7 May 2012. CMK 23842 , 253 mm SL; Laos: Nam Ngum , Ban Thaheua, M. Kottelat, 1 May 2013. CMK 27769 , 225 mm SL; Laos: Saysomboune Province, Nam Ngiep watershed : Nam Chae; M. Kottelat, 22 April 2018 . TCWC 16133.01 , 3 , 255– 310 mm SL; Cambodia: Stung Treng Province, Mekong River at Koh Sralao; C. Montaña et al., 7 Jan 2010 . UMMZ 232334 , 284 mm SL; Cambodia: Stung Treng market, Mekong; W. Rainboth et al. 26 Jan 1995 . UMMZ 234597 , 2 , 287– 309 mm SL; Cambodia: Stung Treng market, Mekong; W. Rainboth et al. 31 Jan 1996 . ZRC 35116, 239 mm SL, Laos: Mekong River below Lee Pee waterfalls, T. Roberts June–July 1993. ZRC 54757, 143 mm SL; Laos: Nam Gnouang at Ban Sop Chat, Ban Sensi and Ban Sopong; T. Roberts, 12 July–22 Aug 1995 . ZRC 54748, 143 mm SL, Laos: Nam Gnouang at Ban Sop Chat , Ban Sensi and Ban Sopong; T. Roberts, 12 July–22 Aug 1995 .

Diagnosis. Channa auroflammea is a member of the Marulius group of the genus Channa characterized by the presence of a conspicuous caudal-fin ocellus in at least one phase of its life cycle. It can be distinguished from all other members of the Marulius group by its colour pattern: dorsum and upper half of body and all median fins of juveniles and adults dark brown to black without separate series of distinct black mid-lateral blotches and light grey belly in preserved specimens, but in life ranging from cream to bright orange. It is further distinguished from C. aurolineata from neighbouring river systems (Chindwin-Irrawaddy, Salween) by fewer lateral line scales (61–65 vs 65–71), fewer vertebrae (58–61 vs. 63–66), and fewer dorsal-fin rays (52–54 vs 55–58) and by the absence of white posterior margins on scales forming the series of mid-lateral blotches. It additionally differs from C. pseudomarulius in having more lateral line scales (61–65 vs 58–61), more vertebrae (58–61 vs 55), and more dorsal- (52-54 vs 47-50) and anal-fin rays (33-36 vs 29-33).

Description. See Figures 2–3 for general appearance and Table 2 for meristic data. A large snakehead reaching at least 600 mm SL. Head 3.3–4.1 times SL, tapering towards snout especially in juveniles, resulting in anteriorly pointed, almost triangular head in lateral view; head dorsoventrally compressed, head width 1.4–1.6 times head depth; a short nasal tube in front of eye; body elongate, circular in cross section, tapering towards the tail where slightly more laterally compressed. Outline rising from snout towards top of head then continuing in almost straight line to tail, ventral outline convex from snout to base of pelvic fin, then continuing in almost straight, slightly rising line to tail. Dorsal fin with long base, 65–72 % SL, with 52–54 rays, originating in front vertical through pelvic-fin base and behind vertical through pectoral-fin base, anal fin long, with 33–36 fin rays. Pectoral fin large with 17–19 rays reaching to end of lateral line drop. Pelvic fin with six rays, inserted slightly behind vertical through pectoral-fin base. Caudal fin large, rounded, with 14 principal rays and 2–3 dorsal and ventral procurrent rays.

Lateral line scales 61–65, anterior section of lateral line canal running straight from supracleithral canal opening posteriorly, then dropping one or two scale rows and continuing in straight line; 15–19 scales predrop, 2–5 scales forming drop and 39–46 scales postdrop; 0–2 scales with lateral line canal on caudal-fin base; 4.5 to 5.5 scales above anterior section of lateral line and 8.5–11.5 scales below. 11 to 12 scales between eye and posterior rim of opercle. 15 to 19 predorsal scales. 58–61 vertebrae, including 4–7 caudal vertebrae.

Colouration. In preservative ( Fig. 2 ). Overall dark brown to black from head along back and upper half of side to tail, with series of dark saddles extending beneath lateral line onto lower half of body; lower half lighter brown with chevron-like markings extending onto upper half of body between dorsal dark saddles. Dorsal, anal, caudal, and pectoral fins dark brown, pelvic fins light brown. Dorsal and anal fins with numerous whitish spots along base and on fin membranes, caudal fin with series of whitish spots, in juveniles up to at least 15 cm SL, caudal fin also with well-developed ocellus near dorsal base formed by black spot surrounded by whitish rim, but ocellus indistinct in larger juveniles and adults. Juveniles also with a light horizontal stripe along upper third of body.

In life ( Fig. 3 ). Based on photographs taken of fresh specimens at Stung Treng market, Cambodia and Nam Ngiep, Laos. Specimen from Stung Treng with brown back, series of black mid-lateral blotches set off conspicuously from bright orange ventral half. Body with numerous tiny white spots, mostly concentrated on area of mid-lateral blotches, but also expressed on opercle at area where dark brown dorsal half grades into orange ventral half. Ventral half of head orange with a number of dark brown spots from rictus to end of opercle. Dorsal, caudal and anal fins dark brown to black with numerous tiny white spots on fin membranes. Pectoral fin dark brown to black with orange base. Pelvic fin whitish grey with anterior fin rays orange. Specimen from Nam Ngiep overall very dark, almost black throughout, only belly and ventral half of head dark greyish brown. Side of head and body and dorsal, caudal and anal fins with numerous tiny white spots. Caudal fin with indistinct ocellus near dorsal base. Pectoral fin dark brown to black. Pelvic fin dark grey.

Genetic difference. The Channa auroflammea COI barcodes were distinct from those of all other valid species currently recognised in the Marulius group, with minimum pairwise COI divergences of 6.6%, 7.6%, 7.4%, and 9.1% observed between C. auroflammea and C. aurolineata , C. marulius , C. marulioides , and C. pseudomarulius , respectively ( Table 3). Four different C. auroflammea haplotypes were observed, all very similar to each other (maximum uncorrected difference = 0.6%), with only one non-synonymous mutation present in the alignment. The most common haplotype was identified in two of the Laos specimens and in one from Cambodia; this was identical to the ‘clade04’ “ Channa marulius ” sequence of Conte-Grand et al.’s (2017) barcoding study. The eight C. auroflammea COI sequences are accessioned in Genbank with numbers MK423209 –16.

Distribution. Channa auroflammea is known from the Mekong basin in Laos and Cambodia and is expected to be found in the Mekong basin in Thailand ( Fig. 1 ).

Etymology. The species name auroflammea , an adjective, is derived from the Latin aurum, Gold, and flammeus, flaming, alluding to the dorsal flame like extensions of the golden-orange belly colouration towards the dark sides and dorsum in some specimens.

Figures

FIGURE 1. Map of the Mekong River Basin showing approximate collection localities of Channa auroflammea specimens and DNA samples examined in this study. Inset shows regional political boundaries of mainland Southeast Asia: Laos (L), Thailand (T), Cambodia (C), and Vietnam (V).

FIGURE 2. Channa auroflammea. (A) BMNH 2015.1.29.13, holotype, 600 mm SL; Cambodia: Ban Lung market; (B) CMK 23842, paratype, 253 mm SL; Laos: Nam Ngum reservoir; (C) ZRC 54747, paratype, 143 mm SL, Laos: Nam Gnouang. (D) CMK, non-type, 81.5 mm SL, Laos: Xe Banghiang (photo: M. Kottelat).

FIGURE 3. Channa auroflammea. (A) ca. 550 mm SL, alive, not preserved, Cambodia, Stung Treng, fish market. Note bright orange gular area of head and ventral half of abdominal and caudal body, small white spots on body and median fins. (B) ca. 500 mm SL, not preserved but DNA sampled, Laos: Nam Ngiep watershed, NamChae. Note very dark overall colouration and absence of orange colour on ventral half (photo: M. Kottelat).

FIGURE 5. Comparison of colour patterns of scales in mid-lateral black blotches in members of the Marulius group. (A) Channa pseudomarulius, 164 mm SL, not preserved, Kerala, Pamba River; (B) Channa marulius, BMNH 2017.5.17.1, 226 mm SL, Myanmar, Rakhine State; (C) C. aurolineata, ca. 500 mm SL, not preserved, Myanmar, Kachin State, Hkamti market; (D) C. auroflammea, ca. 550 mm SL, not preserved, Cambodia, Stung Treng, fish market.