Hemibagrus imbrifer Ng & Ferraris, 2000

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 : 266-268

Hemibagrus imbrifer Ng & Ferraris, 2000

( Fig. 42 )

Hemibagrus imbrifer Ng & Ferraris, 2000: 126 , Fig. 1 (type locality: Mae Nam Moei at Ban Wa Le, Thailand); Ferraris, 2007: 89; Ng & Lim, 2008: 29, Fig. 23 .

Material examined. — THAILAND: ZRC 45406, holotype, 186.6 mm SL , CMK 13445, 1 paratype, 144.2 mm SL, Thailand: Tak province, Salween drainage, Mae Nam Moei at Ban Wa Le , 16°17'24"N 98°42'21"E ).

Diagnosis. — Hemibagrus imbrifer is distinguished from its congeners within this species group having a grey (vs.

brown) body in life, a longer adipose-fin base (38.4–44.2% SL vs. 27.8–39.2), and relatively large sensory pores arranged in vertical columns along the sides of the body (vs. sensory pores not easily visible).

Description. — Biometric and meristic data as in Table 27. General description as for genus. Head depressed and broad, body moderately compressed. Interorbital distance 32% HL. Eye diameter 17% HL.Dorsal profile rising evenly but not steeply from tip of snout to origin of dorsal fin, then sloping gently ventrally from there to end of caudal peduncle. Ventral profile horizontal to origin of anal fin, then sloping dorsally to end of caudal peduncle. Sensory pores of lateral line system readily visible, arranged in nine vertical columns on sides of body. Adipose fin with long base, about 3.5 times length of anal-fin base (38.4–44.2% SL) and spanning most of postdorsal distance. Origin of adipose fin in contact with base of posteriormost dorsal-fin ray. Postadipose distance 8.1–10.1% SL. Dorsal spine stout, without serrations on posterior edge. Pectoral spine stout, with 12–13 large serrations on posterior edge. Caudal-peduncle depth 9.8–11.1% SL. Caudal fin forked; distal margins of upper and lower lobes rounded. Sensory pores on body prominent and arranged in vertical columns along sides of body. Rakers on first gill arch 14. Maximum recorded size 187 mm SL.

Colour. — Dorsal surface of head and body uniform grey; ventral surface of head and body dirty white; adipose fin grey, distal edge fading to light grey; caudal and anal fins grey, with melanophores more dense on fin rays. Distal two-thirds of pectoral and pelvic fins grey, with melanophores more dense on fin rays and proximal third dirty white.

Distribution. — Known from only the Mae Nam Moei River in the Salween (Thanlwin) River drainage ( Fig. 39 ). The Mae Nam Moei marks the border between Thailand and Myanmar.

Remarks. — The photograph of this species in the original description (Ng & Ferraris, 2000: Fig. 1 ) is erroneously captioned. The photograph in question is of the paratype (CMK 13445), and not of the holotype (ZRC 45406) as indicated.

Figures

Fig. 42. Hemibagrus imbrifer, ZRC 45406, holotype, 186.6 mm SL, Thailand: Mae Nam Moei.

Fig. 1. Method of measurements used in this study: 1, Standard length; 2, Predorsal length; 3, Preanal length; 4, Prepelvic length; 5, Prepectoral length; 6, Dorsal-spine length; 7, Dorsal-fin length; 8, Length of dorsal-fin base; 9, Length of anal-fin base; 10, Pelvic-fin length; 11, Pectoral-fin length; 12, Pectoral-spine length; 13, Caudal-fin length; 14, Length of adipose-fin base; 15, Maximum height of adipose fin; 16, Dorsal to adipose distance; 17, Post-adipose distance; 18, Length of caudal peduncle; 19, Depth of caudal peduncle; 20, Body depth at anus; 21, Head length; 22, Head width; 23, Head depth; 24, Snout length; 25, Interorbital distance; 26, Eye diameter.

Fig.23. Hemibagrus capitulum, ZRC 40482, 139.4 mm SL, Borneo: Brunei Darussalam, Sungai Merimbun.

Fig. 39. Map showing collection localities of Hemibagrus pluriradiatus, H. centralus, H. hainanensis, H. imbrifer, and H. variegatus specimens examined in this study