Hemibagrus wyckioides (Fang & Chaux, 1949 )

Ng, Heok Hee & Kottelat, Maurice, 2013, Revision Of The Asian Catfish Genus Hemibagrus Bleeker, 1862 (Teleostei: Siluriformes: Bagridae), Raffles Bulletin of Zoology 61 (1), pp. 205-291 : 276-278

Hemibagrus wyckioides (Fang & Chaux, 1949)

( Fig. 50 )

Macrones wyckioides Fang & Chaux , in Chaux & Fang, 1949: 199, Fig. 3 (type locality: Cambodia).

Macrones rubicauda Bardach, 1959: 32 a (nomen nudum).

Mystus wickii (non Bleeker, 1858) - Taki, 1968: 20.

Mystus wyckii (non Bleeker, 1858) - Taki, 1974: 57; Mai et al, 1992: 193; Jayaram & Sanyal, 2003: 117, Fig. 28 .

Mystus aubentoni Desoutter, 1975: 449 , Figs. 2–3 (type locality: Cambodia, Stung Treng); Kottelat, 1985: 270; Mo, 1991: 130.

Mystus wycki (non Bleeker, 1858) - Taki, 1978: 39.

Mystus nemurus (non Valenciennes, in Cuvier & Valenciennes, 1840) - Cheng & Zheng, 1987: 216, Fig. 1086; Zheng & Dai, 1999: 69, Fig. 33 .

Mystus wyckoides - Kottelat, 1989: 14.

Mystus wyckioides - Cui, 1990: 163, Fig. 166; Rainboth, 1996: 144, Pl. 19, Fig. 147.

Hemibagrus wyckoides - Mo, 1991: 132.

Mystus microphthalmus (non Day, 1878) - Roberts, 1993: 42, Fig. 7 ; Roberts & Warren, 1994: 101.

Hemibagrus wyckioides - Kottelat, 1998: 100, Fig. 148; 2001b: 124, Fig. 332; Baird et al., 1999: 92, Fig. 202; Ng & Rainboth, 1999: 565, Figs. 10 , 11b ; Gaanantkul et al., 2000: 35; Ferraris, 2007: 91; Vidthayanon, 2008: 116; Zheng et al., 2009: 339; Rainboth et al., 2012: 72, Pl. 46, Figs. 948–9.

Hemibagrus microphthalmus (non Day, 1878) - Nguy n, 2005: 361, Fig. 185.

Mekong, 1 km S of Ban Chaem Pong (approx. 30 km SE of Chiang Khong); CAS 95029, 1 ex., 145.0 mm SL, Nam Kok near Tha Ton ; CMK 5044 , 1 ex., 115.8 mm SL, market at Nong Khai ; CMK 5086 , 2 ex., 142.6–155.6 mm SL, market at That Phanom ; UMMZ 213968 , 1 ex., 79.4 mm SL, Nakhon Phanom province : Mekong River, off Ban Tha Kai, 20 km downstream from Mukdahan , 1 km from Thai side, 5 km from Laos side ; UMMZ 213971 , 1 ex., 60.6 mm SL, Ubon Ratchathani province : Huay Kwang, S of Khong Chiam , 3 km up Mun River from Mekong–Mun confluence ; UMMZ 213973 , 1 ex., 159.2 mm SL, Ubon Ratchathani province : Khong Chiam district, Huay Kwang, 1.5 km upstream from Mun River ; UMMZ 214369 , 1 ex., 237.6 mm SL, Ubon Ratchathani province : Khong Chiam district , creek at Ban Tha Mui, mouth into Mekong River ; USNM 348912 , 1 ex., 221.5 mm SL, Ubon Ratchathani province : Mun River at Bung Wai about 7 km W of Ubon ; USNM 317577 , 1 ex., 158.3 mm SL, Nakhon Ratchasima province : Nai Muang, 15°14'N 104°52'E .

CAMBODIA: MNHN 1966–727 , holotype, 402.2 mm SL, Cambodia . MNHN 1974–39 (1), 294.0 mm SL, Stung Treng [holotype of Mystus aubentoni ] ; MNHN 1974–38 , 1 ex., 181.3 mm SL, Battambang [paratype of M. aubentoni ] ; MNHN 1974–40 , 1 ex., 359 mm SL [paratype of M. aubentoni ] ; MNHN 1974–41 , 1 ex., 454 mm SL [paratype of M. aubentoni ] ; MNHN 1974–42 , 1 ex., 446 mm SL, Stung Treng [paratype of M. aubentoni ] ; CAS 93472, 1 ex., 82.9 mm SL, rapids in Se San or Tonlé San , 7 km upstream from Stung Treng ; UMMZ 232312 , 3 ex., 203.5–286.6 mm SL, Stung Treng morning market, 13°30'N 105°58'E .

VIETNAM: UMMZ 224950 , 1 ex., 38.0 mm SL, Phung Ding province: S side of Can Tho Island , 3 km SE of Can Tho .

Chao Phraya drainage: THAILAND: ANSP 59398 , 2 ex., 76.1– 82.7 mm SL, Chieng Mai on Mae Nam Ping . ANSP 59400 , 2 ex., 65.2–73.6 mm SL, Chieng Mai on Mae Nam Ping ; CMK 14480, 1 ex., 159.1 mm SL, Mae Nam Chao Phraya near Uthai Thani .

Diagnosis. — Hemibagrus wyckioides is distinguished from congeners in the H. wyckii species group except H. maydelli in having red (vs. grey) fins. It is distinguished from H. maydelli in having a grey (vs. olive green) body and a greater dorsal to adipose distance (9.6–13.6% SL vs. 4.0–7.0). It further Material examined. — Mekong drainage: LAOS: CAS 94877, 2 ex., 57.7–149.0 mm SL, Mekong at Ban Hang Khone, just below Khone falls ; CMK 12511, 2 ex., 202.4–220.6 mm SL, Khammouan province: Nam Theun at NT2 dam site (17°59'50"N 104°57'10"E) ; CMK 13253, 1 ex., 81.5 mm SL, Vientiane province: confluence of Nam Leuk and Nam Ngong, 18°22'4"N 103°5'27"E ; UMMZ 240596 , 1 ex.: 126.1 mm SL, Bokeo province: Mekong River , 5 km upstream from Houay Xai ; UMMZ 240609 , 1 ex., 136.7 mm SL, Luang Prabang province: Nam Nga, about 3 km upstream from confluence with Nam Ou ; USNM 317621 , 1 ex., Champasak province: morning market at Muang Khong .

THAILAND: ANSP 87236 , 1 ex., 95.9 mm SL, Khemerat, 16°2'N 105°12'E ; CAS 61917, 7 ex., 37.9–235.2 mm SL ; CAS 96788, 2 ex., 63.7–103.8 mm SL ; UMMZ 213974 , 2 ex., 177.9–200.9 mm SL ; ZMA 120.851 , 1 ex., 105.7 mm SL, fish market at Ubon Ratchathani ; CAS 67223, 2 ex., 140.3–193.1 mm SL, Khong Chiam market ; CAS 93280, 1 ex., 129.3 mm SL, Menam Mun, Gaeng Sa- Pu (rapids) at Phibun , 43 km E of Ubon Ratchathani ; CAS 94611, 2 ex., 122.0– 132.6 mm SL, mouth of Huay Ngao where it flows into

differs from H. microphthalmus by a wider head (19.5–23.9% SL vs. 18.0–19.7), a greater interorbital distance (32–37% HL vs. 28–32) and a longer dorsal-fin base (16.3–18.3% SL vs. 13.7–16.7) and from H. wyckii in having a a poorly ossified dorsal spine (thinner than soft dorsal-fin rays; vs. well ossified spine at least as thick as the branched dorsalfin rays) without (vs. with 10–12) serrations on the posterior edge, absence (vs.presence) of pale procurrent caudal-fin rays, grey (vs. cream) cleithral region, and a longer maxillary barbel (reaching to at least the middle of the adipose fin base; 230–297% HL vs. reaching to the middle of the dorsal-fin base; 144–195% HL).

Description. — Biometric and meristic data as in Table 32. General description as for genus. Head extremely depressed and broad; length 28.1–31.7% SL; width 19.5–23.9% SL. Interorbital distance 32–37% HL. Eye diameter 8–16% HL. Body moderately compressed. Dorsal profile rising evenly but not steeply from tip of snout to origin of dorsal fin, then gently sloping ventrally to end of caudal peduncle. Ventral profile horizontal to origin of anal fin, then sloping dorsally to end of caudal peduncle. Adipose fin with a moderately long base (about 1.5–2.0 times anal-fin base) and gentlysloping anterior margin. Dorsal spine thin and poorly ossified, without serrations on posterior edge. Adpressed dorsal fin reaching adipose-fin origin; dorsal fin-base length 16.3–18.3% SL. Pectoral spine stout, with 11–15 serrations on posterior edge. Adipose-fin origin separated from base of last dorsal-fin ray by distance of 9.6–13.6% SL. Postadipose distance 12.7–15.1% SL. Caudal-peduncle length 15.4–18.9% SL; caudal-peduncle depth 6.7–8.1% SL. Caudal fin forked, upper and lower lobes rounded posteriorly; first principal ray of the upper lobe elongated, forming filament. Maxillary barbel reaching to at least middle of adipose fin base (230–297% HL) Maximum recorded size 1300 mm SL (Roberts & Jumnongthai, 1999).

Colour. — Adult specimens with dorsal surface of head and body uniform grey (live or freshly-dead specimens generally have darker shade which tends to fade on preservation); ventral surface of head and body dirty white; adipose fin grey, distal edge orange in life but fading to light grey on preservation; caudal fin red or grey with red distal margins in life, fading to grey with very light grey procurrent and first principal caudal-rays on preservation; all other fins grey with distal portions of fin rays and inter-radial membranes occasionally orange or red in life ( Fig. 50b ), fading to light grey on preservation. Red colouration on fins absent in some specimens. Live colouration of juvenile specimens similar, but with white procurrent and first principal caudal-rays.

Distribution. — Known from the Mekong and Chao Phraya drainages ( Fig. 49 ).

Habitat and biology. — Hemibagrus wyckioides is probably the largest Southeast Asian species of the genus, reportedly reaching sizes of up to 1300 mm TL (Roberts & Jumnongthai, 1999) and weights of up to 70 or 80 kg (Roberts, 1993). It is a predatory species feeding on shrimps, crabs and fish and is not migratory, but enters the flooded forest in the Mekong during high water (July–October; Roberts, 1993b). Specimens about 30 mm SL have been collected in April in Laos (MK, pers. obs.).

Remarks. — Hemibagrus wyckioides has been considered a junior synonym of H. microphthalmus by Roberts (1993) and Roberts & Warren (1994), evidently on the basis of similar external anatomies. However, there are differences in biometrics and fin colour as outlined above. Some of the records of H. nemurus from the Lancangjiang (upper Mekong) River drainage (Menglun) in Yunnan (e.g. Cheng & Zheng, 1987; Zheng & Dai, 1999) are in fact H. wyckioides .

Figures

Fig. 50. Hemibagrus wyckioides: a, CMK 14480, 159.1 mm SL; Thailand: Mae Nam Chao Phraya near Uthai Thani; b, Specimen about 400 mm SL (not preserved); Laos: Nam Kading drainage: Nam Theun, at Keng Sauak.

Fig.3. Map showing collection localities ofHemibagrus baramensis specimens examined in this study.

Fig. 28. Hemibagrus spilopterus, ZRC 40305, 144.3 mm SL, Thailand: Bangkok.

Fig.2. Hemibagrus baramensis, ZRC 42742, 150.0 mm SL; Borneo: Sarawak, Mulu.

Fig. 33. Hemibagrus bongan, ZRC 43014, 174.9 mm SL, Borneo: Kalimantan Barat, Sungai Haloi.

Fig. 7. Hemibagrus guttatus, ZRC 42555, 328.4 mm SL, China: Beijiang river.

Fig. 10. Map showing collection localities of Hemibagrus macropterus and H. vietnamicus specimens examined in this study

Fig. 11. Hemibagrus vietnamicus, CMK 15391, 179.7 mm SL; Laos: Nam Ma.

Fig. 49. Map showing collection localities of Hemibagrus microphthalmus and H. wyckioides specimens examined in this study.