Hemibagrus variegatus 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 : 268-270

Hemibagrus variegatus Ng & Ferraris, 2000

( Fig. 43 )

Hemibagrus variegatus Ng & Ferraris, 2000: 139 , Fig. 12 (type locality: Tenasserim River, Myanmar); Vidthayanon et al., 2005: 95; Ferraris, 2007: 91.

Material examined. — MYANMAR: BMNH 1992.11.16:11, holotype, 121.2 mm SL, Tenasserim (Taninthari) River . UMMZ 248183 , 1 ex., 85.9 mm SL ; ZRC 51967, 3 ex., 86.8–285.6 mm SL; Taninthayi division, Tenasserim River drainage in the vicinity of Same , 13°36'N 99°2'E .

Diagnosis. — Hemibagrus variegatus can be easily distinguished from congeners in this species group in having a longer post-adipose distance (12.9–14.1% SL vs. 8.1–11.6), and a mottled greenish yellow (vs. uniform grey or brown) body with irregular dark vertical bars in life. It further differs from congeners in this species group except for H. centralus in having more gill rakers on the first gill arch (19–21 vs. 14–18).

Description. — Biometric and meristic data as in Table 28. General description as for genus. Head depressed and broad, body moderately compressed. Interorbital distance 24–30% HL. Eye diameter 14–23% 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. Adipose fin with long base, about 3.0 times length of anal-fin base (28.0–34.6% SL) and spanning most of postdorsal distance. Origin of adipose fin separate from base of posteriormost dorsal-fin ray by distance of 0.0–8.6% SL. Post-adipose distance 12.9–14.1% SL. Dorsal spine stout, without serrations on posterior edge. Pectoral spine stout, with 9–22 large serrations on posterior edge. Anterior base of adipose fin not touching base of posterior ray of dorsal fin. Caudal-peduncle depth 7.6–9.1% SL. Caudal fin forked; distal margins of upper and lower lobes straight. Sensory pores on body not prominent. Rakers on first gill arch 19–21. Maximum recorded size 800 mm SL ( Vidthayanon et al., 2005).

Colour. — Dorsal surface of the head and body brown with irregular dark brown markings forming a variegated pattern; this colour fades to a dirty white on the ventral surface. All fins brown, with melanophores on fin rays and interradial membranes; melanophores are more concentrated in the interradial membranes of the dorsal, pectoral, pelvic and anal fins. Colour in life greenish yellow.

Distribution. — Known only from the Tenasserim (Thaninthari) River drainage in southern Myanmar ( Fig. 39 ).

Habitat. — Hemibagrus variegatus inhabits the upper reaches of rivers, where the substrate is composed primarily of rocks and gravel ( Vidthayanon et al., 2005).

Figures

Fig. 43. Hemibagrus variegatus, ZRC 51967, 285.6 mm SL, Myanmar: Tenasserim River drainage.

Fig. 12. Dorsal views of heads of: a, H. menoda, UMMZ 208726, 202.6 mm SL; b, H. peguensis, CAS 133789, 212.7 mm SL. Scale bar = 10 mm.

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