Hemibagrus hoevenii (Bleeker, 1846)

Hemibagrus hoevenii (Bleeker, 1846) View in CoL

( Fig. 27 View Fig )

Bagrus Hoevenii Bleeker, 1846a: 26 View in CoL (type locality: Malaysia: Johor: Muar River at Kampong Bukit Kebong); 1846b: 285; 1852a: 410, 413; 1853b: 176, 181; 1854a: 429, 432; 1854b: 65; 1855d: 393, 396; 1855e: 417, 418; 1856b: 9;1857b: 476; 1857a: 25; 1858c: 197; 1858e: 153; 1858f: 4, 7; 1858a: 417; 1858g: 3, 4; 1859d: 370; 1859g: 134; 1860b: 18; 1860c: 1; Ng & Lim, 2008: 23, Fig. 17 View Fig .

Hemibagrus Hoevenii View in CoL - Bleeker, 1862: 56, Pl. 70.

Macrones Hoevenii View in CoL - Vinciguerra, 1880: 170; 1926: 609.

Macrones nemurus var. hoeveni - Volz, 1904: 468.

Macrones hoeveni - Volz, 1907: 166.

Macrones nemurus (in part) - Weber & de Beaufort, 1913: 341.

Hemibagrus hoevenii View in CoL - Bleeker, 1865b: 175; Kottelat & Lim, 1995a: 42; 1995b: 238; Ng & Rainboth, 1999: 557; Tan & Ng, 2000: 271; Ferraris, 2007: 88.

Hemibagrus nemurus View in CoL (non Valenciennes, in Cuvier & Valenciennes, 1840) - Hashim & Zainuddin et al., 2012: 409.

Material examined. — SUMATRA: Jambi: ZRC 29513–29515 View Materials , 3 ex., 271.6–317.4 mm SL, ZRC 29519, 1 ex., 266.6 mm SL , Jambi; ZRC 39130, 1 ex., 143.3 mm SL, Batang Berbak at Telogolima ; ZRC 41526, 2 ex., 232.7–244.4 mm SL, Pasar Angso Duo (fish market) , Jambi; ZRC 29544, 1 ex., 360 mm SL

SUMATRA: Sumatera Selatan: ZRC 29546–29551 View Materials , 6 ex., 298.6–357 mm SL, Palembang ; ZRC 51969, 2 ex., 78.0– 117.3 mm SL; Sungai Gelam, approx. 1 hour downriver from Kenten Laut (Palembang), 2°50'14.6"S 104°47'49.1"E GoogleMaps .

PENINSULAR MALAYSIA: ZRC 37472, neotype, 114.7 mm SL, Johor: Sungai Muar at Kampung Bukit Kebong ; ZRC 40590, 10 ex., 169.1–292.0 mm SL, Johor: Muar, Seram III, Tanjung Selabu port ; CMK 13014, 1 ex., 123.0 mm SL ; ZRC 29573–29582 View Materials , 10 ex., 89.1–122.9 mm SL, Johor: Kota Tinggi .

BORNEO: Sarawak: ZRC 38002, 2 ex., 193.8–223.9 mm SL ; ZRC 40511, 8 ex., 176.7–255.5 mm SL, Marudi market ; ZRC 40499, 3 ex., 153.9–210.1 mm SL, Miri, Kampung Bakung from Sungai Bakung, turnoff after 62 km to Batu Niah .

BORNEO: Kalimantan Barat: ZRC 29385–29388 View Materials (4), 259.7–301.0 mm SL, Kapuas River at Pontianak .

BORNEO: Kalimantan Tengah: BMNH 2001.1 .15.1365, 1 ex., 274.0 mm SL, market at Muara Teweh; ZRC 51972, 1 ex., 189.2 mm SL; Kasongan market, from Katingan River , 1°54'S 113°23'E GoogleMaps .

BORNEO: Kalimantan Selatan: ZRC 29377–29379 View Materials , 3 ex., 240.7– 261.0 mm SL, ZRC 40021, 2 ex., 216.7–252.0 mm SL, Banjarmasin, Pasar Lima Beton .

Diagnosis. — Hemibagrus hoevenii differs from congeners of the H. nemurus species group in having the premaxillary tooth band partially exposed (vs. not exposed) when the mouth is closed, tapering (vs. rounded) caudal-fin lobes, presence (vs. absence) of a broad and conspicuous dark margin around the caudal fin, a triangular (vs. rounded) anal fin, narrower (vs. broader) membranes of the dorsal fin which give it a triangular (vs. rounded) appearance, and very long filamentous extensions of the first two dorsal-fin rays that reach, when present, beyond the posterior base of the adipose fin (vs. filamentous extensions if present not reaching beyond middle of adipose-fin base).

Description. — Biometric and meristic data as in Table 15. General description as for genus. Head depressed and broad, body moderately compressed; head width 59–75% HL. Interorbital space flat. Eye diameter 12–20% HL. Premaxillary tooth band partially exposed when mouth is closed. 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 base short, approximately as long as anal-fin base; maximum height 4.1–6.4% SL (1.9–3.6 times in length of adipose-fin base). Adipose-fin origin separated from base of last dorsal-fin ray by distance of 9.6–16.0 % SL. Dorsal spine stout, with 7–13 serrations on posterior edge. Dorsal fin with anteriormost branch of each ray longer than other branches, imparting triangular distal margin to fin; membranes narrow, imparting triangular appearance. Adpressed dorsal fin (excluding filamentous extensions of rays) not reaching adipose fin; very long filamentous extensions of first two rays reaching beyond posterior base of adipose fin typically present in individuals larger than approx. 200 mm SL; filamentous extensions not as prominent in individuals smaller than approx. 200 mm SL and when present, not reaching beyond middle of adipose-fin base. Pectoral spine stout, with 13–25 large serrations on posterior edge. Anal fin triangular, origin slightly posterior to adipose origin. Caudal fin forked; upper and lower lobes tapering. Maxillary barbels reaching barbels reaching at least vertical through base of last anal-fin ray (234–297% HL). Maximum recorded size 360 mm SL.

Colour. — Dorsal surface of head and body uniform brownish-grey; ventral surface of head and body dirty white; adipose fin darker brownish-grey than body but without distinct dark spot; fin-rays and inter-radial membranes of dorsal, pectoral, pelvic and anal fins grey; tips of first two or three pelvic-fin rays and second to fifth anal-fin rays whitish in life. Caudal fins with black procurrent and upper and lower principal rays, faint black distal margin and reddish bases of fin lobes in life; only black colouration on procurrent and upper and lower principal caudal-rays evident in preserved material. Dorsal surface of barbels brownish-grey, ventral surface dirty white.

Distribution. — Hemibagrus hoevenii is known from river drainages in Borneo (Baram, Barito, Kapuas, Katingan), Sumatra (Batang Hari, Musi) and the Malay Peninsula (Johor, Muar, Pahang; Fig. 26 View Fig ).

Habitat and biology. — Hemibagrus hoevenii is found primarily in the lower reaches of rivers, although it is not restricted to such habitats. The furthest inland records for this species are at Muara Teweh (Barito River drainage) and Sintang (Kapuas River drainage), both about 300 km from the sea. In the lower Batang Hari and Musi river drainages in eastern Sumatra, it has been found in large rivers with turbid water and a substrate of fine mud. It is apparently capable of withstanding low salt concentration.

Remarks. — Hemibagrus hoevenii was previously considered a junior synonym of H. nemurus by most authors since Günther (1864), but was shown by Kottelat & Lim (1995) to be a distinct species. Since the holotype of H. hoevenii was probably lost (the circumstances surrounding the probable loss are discussed in Kottelat et al., 1994), a neotype was subsequently designated (International Commission for Zoological Nomenclature, 1996, Opinion 1840).