Hemibagrus microphthalmus (Day, 1878)

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 : 274-276

Hemibagrus microphthalmus (Day, 1878)

( Fig. 48 )

Macrones microphthalmus Day, 1878: 446 , Pl. 100 Fig. 4 (type locality: Irrawaddy River, Myanmar), 1889: 154; Vinciguerra, 1890: 225; Ferraris et al., 2000: 299.

Mystus (Mystus) menoda microphthalmus - Jayaram, 1954: 547; 1966: 446.

Mystus microphthalmus - Tint Hlaing, 1971: 513; Jayaram, 1977: 34; Viswanath & Singh, 1986: 197, Fig. 1 ; Mo, 1991: 130; Talwar & Jhingran, 1991: 566; Vishwanath et al., 1998: 323; Jayaram, 1999: 236; Jayaram & Sanyal, 2003: 80, Fig. 15 ; Khan, 2008: 33, Fig. 13 .

Hemibagrus microphthalmus - Ukkatawewat & Vidthayanon, 1998: 46; Ng & Ferraris, 2000: 133, Fig. 8 ; Vidthayanon et al., 2005: 94; Ferraris, 2007: 90; Vishwanath et al., 2007: 137; Mahanta et al., 2011: 347.

Material examined. — MYANMAR: ZSI 2952 , 1 ex., syntype, 138.9 mm SL , AMS B.7918 1 ex., syntype, 164.0 mm SL, Irrawaddy River ; BMNH 1893.2 .16.7, 1 ex., 133.5 mm SL, Myanmar ; CAS

93192, 3 ex., 132.0– 151.5 mm SL; USNM 44754 , 1 ex., 158.7 mm SL; USNM 344670 , 2 ex., 201.6–239.8 mm SL, Irrawaddy River drainage, Mandalay; NRM 13892 , 1 ex., 116.1 mm SL, Mandalay division: Irrawaddy River drainage, Mandalay area; NRM 24979 , 2 ex., 144.6–165.1 mm SL, Sagaing division: Irrawaddy River drainage, Shweli River ; NRM 31072 , 1 ex., 147.1 mm SL, Yangon division: Yangon River at Yangon .

THAILAND: CMK 14706, 1 ex., 204.6 mm SL, Tak province: Mae Nam Moei at Mae Sarid , 17°26'25"N 98°3'41"E .

Diagnosis. — Hemibagrus microphthalmus is distinguished from both H. wyckioides and H. maydelli in having grey (vs. red) fins in life. It differs from H. wyckii in having, a poorly ossified dorsal spine (thinner than soft dorsal-fin rays; vs. well ossified spine at least as thick as the branched dorsal-fin rays) without (vs. with 10–12) serrations on the posterior edge, absence (vs. presence) of pale procurrent and first principal caudal-fin rays and a grey (vs. cream) cleithral region. Hemibagrus microphthalmus further differs from H. maydelli in having a longer and less deep caudal peduncle (length 16.4–18.1% SL vs. 15.3–16.1; depth 6.8–7.7% SL vs. 7.8–8.5), a shorter head (29.4–31.0% SL vs. 30.8–32.4), a greater dorsal to adipose distance (8.6–14.2% SL vs. 4.0–7.0), a smaller eye (diameter 9–11% HL vs. 12), and from H. wyckioides by a narrower head (width 18.0–19.7% SL vs. 19.5–23.9), a smaller interorbital distance (28–32% HL vs. 32–37), a shorter dorsal-fin base (13.7–16.7% SL vs. 16.3–18.3), a longer maxillary barbel (reaching to at least the middle of the adipose fin base; 256–301% HL vs. reaching to the middle of the dorsal-fin base; 144–195% HL) and grey (vs. reddish) caudal and distal margin of dorsal fins.

Description. — Biometric and meristic data as in Table 31. General description as for genus. Head extremely depressed and broad; length 29.4–31.0% SL; width 18.0–19.7% SL. Interorbital distance 28–32% HL. Eye diameter 9–11% 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 moderately long base (about 1.5–2.0 times anal-fin base) and gently-sloping anterior margin. Dorsal spine thin and poorly ossified, without serrations on posterior edge. Adpressed dorsal fin reaching adipose-fin origin. Pectoral spine stout, with 9–10 serrations on posterior edge. Adipose-fin origin separated from base of last dorsal-fin ray by distance of 8.6–14.2% SL. Postadipose distance 12.4–16.1% SL. Caudal-peduncle length 16.4–18.1% SL; caudal-peduncle depth 6.8–7.7% SL. Caudal fin forked; distal margins of upper and lower lobes rounded. Maxillary barbel reaching to at least middle of adipose fin base (256–301% HL). Maximum recorded size 1500 mm SL ( Vidthayanon et al., 2005).

Colour. — Preserved specimens with dorsal surface of head and body uniform grey (live or freshly-dead specimens generally darker, fading 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 grey with very light grey procurrent and outer principal caudal-rays in life and on preservation; all other fins grey. Maxillary barbel white.

Distribution. — Known from the Salween (Thanlwin), Irrawaddy (Irrawaddy) and Sittang (Sittoung) River drainages in Myanmar and Thailand, and the Manipur River drainage in India ( Fig. 49 ).

Remarks. — This species has been reported to have red fins in life by Ng & Ferraris (2000), which is in error (in part caused by confusion with H. wyckioides ). The fins of this species are grey in life.

Figures

Fig. 48. Hemibagrus microphthalmus, CMK 14706, 204.6 mm SL, Thailand: Mae Name Moei.

Fig. 4. Hemibagrus sabanus, ZRC 40493, 104.9 mm SL, Borneo: Sabah, Segama River.

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. 15. Map showing collection localities of Hemibagrus menoda and H. punctatus specimens examined in this study.

Fig. 13. Cleithral processes of: a, H. menoda, UMMZ 208726, 202.6 mm SL; b, H. peguensis, CAS 89005, 261.9 mm SL. Scale bar = 5 mm.

Fig. 8. Map showing collection localities of Hemibagrus guttatus specimens examined in this study.

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