Hemibagrus filamentus
Creators: name: Ng, Heok Hee
name: Kottelat, Maurice
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Siluriformes
Bagridae
Hemibagrus
Hemibagrus filamentus

description: <i>Hemibagrus filamentus</i> (Fang &amp; Chaux, 1949) (Fig. 24) <i>Macrones filamentus</i> Fang &amp; Chaux, in Chaux &amp; Fang, 1949: 200, Fig. 4 (type locality: Cambodia). <i>Mystus filamentus</i> - Lim et al., 1996: 382; Rainboth 1996: 144, Pl. 19 Fig. 147. <i>Hemibagrus filamentus</i> - Ng &amp; Rainboth, 1999: 555, Fig. 1; Gaanantkul et al., 2000: 34; Kottelat, 2001b: 122, Fig. 327; Ferraris, 2007: 88; Vidthayanon, 2008: 114; Rainboth et al., 2012: 72, Plate 45, Fig. 943. <b> <i>Material examined</i>.</b> — LAOS: CMK 13252, 6 ex., 54.7–186.2 mm SL, Vientiane province: confluence of Nam Leuk and Nam Ngong, 18°22'4"N 103°5'27"E; CMK 13357, 1 ex., 159.4 mm SL, Vientiane province, Houay Sala Yai, a tributary of Nam San, 18°35'17"N 103°5'0"E; CMK 13393, 9 ex., 63.2–129.3 mm SL, Vientiane province, Nam San downstream of Ban Pa Man, 18°32'3"N 102°55'48"E; UMMZ 238567, 30 ex., 62.0–138.0 mm SL, Vientiane province: Nam Tou, 8 km upstream from confluence with Nam Ngum reservoir; UMMZ 238677, 8 ex., 44.0–66.0 mm SL, Vientiane province: Nam Ngao at S end of Nam Ngum reservoir; UMMZ 240634, 12 ex., 50.0– 144.5 mm SL, Vientiane province: Nam Ti at junction with Nam Ngum and upstream 100 m; NRM 15013, 1 ex., 236.8 mm SL, Sedone River, Pakse, 14°9'N 105°50'E; NRM 15019, 1 ex., 198.5 mm SL; NRM 15020, 1 ex., 191.9 mm SL; NRM 15022, 1 ex., 251.6 mm SL, Laos. CAMBODIA: MNHN 1966–728, holotype, 419.8 mm SL, Cambodia; UMMZ 232423, 3 ex., 68.7–102.1 mm SL, Siem Reap: floating village at mouth of Siem Reap River, Mekong drainage (13°16'N 103°48'E); UMMZ 232462, 1 ex., 150.6 mm SL, Siem Reap: fish trap W of floating village at mouth of Siem Reap River, Mekong drainage, 13°16'N 103°46'E; UMMZ 232698, 5 ex., 151.8–175.1 mm SL, Kompong Chhnang morning market, Mekong drainage. <b> <i>Diagnosis</i>.</b> — <i>Hemibagrus filamentus</i> is distinguished from <i>H. capitulum</i> in having a longer, narrower head (head width 55–60% HL vs. 59–70), from <i>H. fortis</i> in having a shorter, deeper adipose fin (maximum height of adipose fin 2.3–3.2 times in the length of its base vs. 2.8–4.9) and the anteriormost branch of dorsal-fin rays longer than other branches (vs. branches of the dorsal-fin rays of almost equal length.) giving the dorsal fin a jagged (vs. rounded) distal margin (Fig. 20), and from <i>H. hoevenii</i> in having the premaxillary tooth band not (vs. partially) exposed when the mouth is closed, rounded (vs. tapering) caudal-fin lobes, absence (vs. presence) of a broad and conspicuous dark margin around the caudal fin, a rounded (vs. triangular) anal fin, broader membranes of the dorsal fin which give it a rounded (vs. triangular) appearance, and filamentous extensions on the dorsal fin not reaching beyond middle of adipose-fin base (vs. very long filamentous extensions of the first two dorsalfin rays that reach beyond the posterior base of the adipose fin). It differs from <i>H. nemurus</i> in having a relatively longer and narrower head (head width 55–60% HL vs. 60–69) and a smaller dorsal to adipose distance (7.7–10.9% SL vs. 10.2–16.2), and from <i>H. spilopterus</i> in having a smaller dorsal to adipose distance (7.7–10.9% SL vs. 10.8–17.6), a flat (vs. gently convex) interorbital space, and dorsal-fin rays (excluding filamentous extensions) reaching beyond (vs. not reaching or just reaching) the adipose-fin origin. <b> <i>Description</i>.</b> — Biometric and meristic data as in Table 13. General description as for genus. Head depressed and broad, body moderately compressed; head width 55–60% HL. Interorbital space flat. Eye diameter 10–15% HL. Premaxillary tooth band not 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 5.0–7.2% SL (2.3–3.2 times in length of adipose-fin base). Adipose-fin origin separated from base of last dorsal-fin ray by distance of 7.7–10.9% SL. Dorsal spine stout, with 6–10 serrations along posterior edge. Anteriormost branch of each dorsal-fin ray longer than other branches, imparting jagged distal margin to fin; membranes broad, imparting rounded appearance. Adpressed dorsal fin (excluding filamentous extensions of rays) reaching beyond adipose-fin origin; filamentous extensions not reaching beyond middle of adipose-fin base. Pectoral spine stout, with 13–18 large serrations along posterior edge. Anal fin rounded, origin slightly posterior to adipose origin. Caudal fin forked; upper and lower lobes rounded. Maxillary barbels reaching barbels reaching at least vertical through base of last anal-fin ray (221–265% HL). Maximum recorded size 420 mm SL. <b> <i>Colour</i>.</b> — Dorsal surface of head and body uniform brownish-grey; ventral surface of head and body dirty white; adipose fin brownish-grey, without black spot; fin-rays and inter-radial membranes of all fins grey; dorsal surface of barbels brownish-grey, ventral surface dirty white. <b> <i>Distribution</i>.</b> — <i>Hemibagrus filamentus</i> is known from the middle and lower Mekong in Laos, Thailand and Cambodia (Fig. 22). <b> <i>Habitat and biology</i>.</b> — <i>Hemibagrus filamentus</i> is found in slow-flowing or standing waters, moving into flooded forests during periods of high water levels. It feeds on crustaceans and fishes (Rainboth, 1996).
description: Published as part of <i>Ng, Heok Hee &amp; Kottelat, Maurice, 2013, Revision Of The Asian Catfish Genus Hemibagrus Bleeker, 1862 (Teleostei: Siluriformes: Bagridae), pp. 205-291 in Raffles Bulletin of Zoology 61 (1)</i> on pages 238-239, DOI: 10.5281/zenodo.5351788
description: {"references": ["Chaux, J. &amp; P. W. Fang, 1949. Catalogue des Siluroidei d'Indochine de la collection du laboratoire des peches coloniales au museum, avec la description de six especes nouvelles. Bulletin du Museum National d'Histoire Naturelle, 2 e serie, 21: 194 - 201.", "Lim, P., S. Lek, S. T. Touch, S. - O. Mao &amp; B. Chhouk, 1996. Diversity and spatial distribution of freshwater fish in Great Lake and Tonle Sap river (Cambodia, Southeast Asia). Aquatic Living Resources, 12: 379 - 386.", "Rainboth, W. J., 1996. Fishes of the Cambodian Mekong. FAO Species Identification Field Guide for Fishery Purposes. FAO, Rome. Xi + 265, 27 pls.", "Gaanantkul, K., C. Vidthayanon, &amp; A. Termvidchakorn, 2000. Fishes of the Bueng Borapet Swamp (Lower Chao Phraya Drainage). Aquatic Natural Resources Museum, Department of Fisheries, Bangkok. 83 pp. (Text in Thai).", "Kottelat, M., 2001 b. Fishes of Laos. Wildlife Heritage Trust, Colombo. 198 pp.", "Ferraris, C. J., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa, 1418: 1 - 628.", "Vidthayanon, C., 2008. Field Guide to the Fishes of the Mekong Delta. Mekong River Commission, Vientiane. 288 pp.", "Rainboth, W. J., C. Vidthayanon &amp; D. Y. Mai, 2012. Fishes of the greater Mekong ecosystem with species list and photographic atlas. Miscellaneous Publications. Museum of Zoology, University of Michigan, 201: i - xvi + 1 - 172, 121 pls."]}