Hemibagrus velox, Ng, 2000

Ng, H. H. Tan H. H., 2000, The cat ® shes (Teleostei: Siluriformes) of central Sumatra, Journal of Natural History 34, pp. 267-303 : 272-276

Hemibagrus velox , sp. nov.

(®gures 2±4)

Bagrus planiceps (non Valenciennes, in Cuvier and Valenciennes, 1840): Bleeker, 1858a: 25; 1858b: 154 ±156 (in part); 1860a: 8, 46.

Hemibagrus planiceps (non Valenciennes, in Cuvier and Valenciennes, 1840): Bleeker, 1862: 56 ±57 (in part); Hubrecht, 1887: 11.

Macrones planiceps (non Valenciennes, in Cuvier and Valenciennes, 1840): GuÈnther, 1864: 81 (in part); Weber, 1894: 420; Volz, 1904: 468; 1907: 166 ±167; Weber and de Beaufort 1913: 342 ±343 (in part); Regan, 1920: 308.

Mystus planiceps (non Valenciennes, in Cuvier and Valenciennes, 1840): Kottelat et al., 1993: 66 (in part).

HOLOTYPE. MZB 9305 , 175 .0 mm SL; Sumatera Barat: Sungai Dareh, Pulau Punjung market; H. H. Tan and H. H. Ng, 22 Jul 1997.

PARATYPES. CMK 9038 (1), 132.3 mm SL; Riau: Kecamatan Seberida , Sungai Gangsal; A. J. Whitten, 30 Nov 1991. UMMZ 155684 (2), 183.7, 194.8 mm SL ; Sumatera Barat: Danau Singkarak ; A. Thienemann, 23 Feb 1929. UMMZ 155685 (4), 191.4±263.6 mm SL; UMMZ 155717 (2), 240.3, 276.9 mm SL; UMMZ 155718 , (3), 261.8±277.0 mm SL ; Sumatera Selatan: Danau Ranau; A. Thienemann, date unknown. ZMA 121 .627 (5), 162.0±185.0 mm SL ; Sumatera Barat: highlands of Padang, Batang Pangian; E. Jacobson, Mar 1914. ZMA 121 .628 (3), 238.0±357.0 mm SL ; Sumatera Barat: highlands of Padang, Batang Pangian, from the cave of Buo; E. Jacobson, Mar 1914. ZMA 121 .629 (1), 264.0 mm SL ; Sumatera Barat: highlands of Padang , Batang Sario near Puntian (Kumanis); E. Jacobson, Mar 1915. ZRC 40549 (1), 269.0 mm SL ; Jambi: Kerinci, Sungaipenuh market; H. H. Tan et al., 10± 11 Jun 1996. ZRC 40550 (2), 236.0, 249.0 mm SL ; Jambi: Kerinci, Sungaipenuh market; H. H. Tan et al., 10± 11 Jun 1996. ZRC 41503 (3), 145.2± 199.0 mm SL ; Jambi: Kerinci, Sungaipenuh market; T. H. T. Tan, 16± 23 May 1997. ZRC 41505 (23), 68.7±162 mm SL; data as for holotype .

Non-types. BMNH 1889.11.12 :6 1 (1), 224.0 mm SL; Sumatera Utara: Deli (= Medan); collector and date unknown. BMNH 1915.8.24 : 12, (1), 212.0 mm SL; Jambi: Korinche (= Kerinci ) Lake; Robinson and Kloss expedition, 26 May 1914 . CMK 4441 (1), 187.4 mm SL; Sumatera Utara: Sungai Seruai at Biru Biru; Bianco and Kottelat, 17 Sep 1984 . CMK 4455 (1), 75.3 mm SL; Sumatera Utara: Sungai Seruai at Biru Biru; Bianco and Kottelat, 18 Nov 1984 . CMK 4625 (3), 78.1±143.0 mm SL; Sumatera Barat: market at Solok; Bianco and Kottelat, 4 Dec 1984 . ZMA 121 .812 (2), 179.8, 223.2 mm SL; Sumatera Barat: Danau Singkarak; M. Weber, 1888 . ZMA 121 .813 (1), 129.0 mm SL; Sumatera Utara: Serdang , Sungai Ular; K. van Deden, 1 Jul 1909 .

Comparative material. H. bongan: RMNH 7548 (2), syntypes, 60.4, 128.2 mm SL; Borneo : Bongan. FMNH 68063 (7), 41.7±216 mm SL; Borneo : Sarawak, Third Division, headwaters of Baleh river, 1000±1700 ft.

H. gracilis: ZRC 21484 (1), holotype, 247.0 mm SL; ZRC 21482, 21486 ±21487 (3), paratypes, 162.0±214.0 mm SL; Peninsular Malaysia: Johor, Ulu Endau, Sungai Jasin. ZRC 8294 ±8295 (2), paratypes, 236.0, 266.0 mm SL; ZRC 8757 ±8759 (3), paratypes, 230.0±277.0 mm SL; Peninsular Malaysia: Pahang, Rompin , Sungai Kinchin. ZRC 8296 (1), paratype, 198.0 mm SL; Peninsular Malaysia: Pahang, Rompin , Sungai Kinchin at conūence of Sungai Selindang. ZRC 8726 ±8728 (3), paratypes, 182.0±264.0 mm SL; Peninsular Malaysia: Pahang, Rompin , Sungai Kernam (tributary of Sungai Kinchin). ZRC 8752 ±8753 (2), paratypes, 295.0, 405.0 mm SL; Peninsular Malaysia: Johor-Pahang border, Sungai Taku (tributary of Sungai Endau).

H. planiceps: BMNH 1870.6.7:11 ±13 (3), 163±176 mm SL; Java. MNHN B615 (1), 97.9 mm SL; RMNH 2956 (1), 283 mm SL (holotype of Bagrus anisurus ); RMNH 2939 (1) 179 mm SL; Java. ZMA 121 .593 (3), 67.5±124.7 mm SL; Java: Buitenzorg [= Bogor]. MZB 9313 (4), 198±216 mm SL; ZRC 42563 (9), 171±263 mm SL; Java: Garut, Cimanuk , Kampung Patro , 7ss10¾52.7 ² S 107ss56 ¾13.1 ² E.

Diagnosis. Hemibagrus velox can be di erentiated from its congeners by a unique combination of the following characters: caudal peduncle depth 6.2±7.5% SL, the upper lobe of the caudal ®n regularly tapering, genital papilla of males reaching anal origin (®gure 3a), anus separated from genital appendage by a distance of 4.3±5.9% SL, irregular serrations on the posterior edge of the dorsal spine (®gure 4b), snout length 33.3±38.9% HL, interorbital distance 29.4±33.9% HL, length of maxillary barbel 198.3±238.2% HL, length of inner mandibular barbel 44.7±52.1% HL, 50±51 vertebrae and 10±11 branchiostega l rays.

Description. Head depressed and broad, body moderately compressed. Dorsal pro®le rising evenly but not steeply from tip of snout to origin of dorsal ®n, then sloping gently ventrally from there to end of caudal peduncle. Ventral pro®le horizontal to origin of anal, then sloping dorsally to end of caudal peduncle. In % SL: head length 24.3±26.1, head width 16.1±19.6, predorsal distance 35.4±39.6, preanal length 66.4±69.6, prepelvic length 48.7±54.1, prepectoral length 21.9±25.0, body depth at anus 10.2±13.2, length of caudal peduncle 17.8±20.8, depth of caudal peduncle 6.2±7.5, pectoral-spine length 15.4±17.4, pectoral-®n length 16.3±20.0, length of dorsal-® n 24.8 ±27.6, length of dorsal-®n base 13.9±16.6, pelvic-®n length 12.7±15.7, length of anal-®n base 13.3±16.0, caudal-®n length 19.6±25.3, length of adipose-®n base 13.4±17.6, adipose maximum height 3.9±5.0, dorsal to adipose distance 13.8±21.4; in % HL: snout length 33.3±38.9, interorbital distance 29.4±33.9, eye diameter 14.2±21.9, nasal barbel length 30.2±43.1, maxillary barbel length 198.3± 238.2, inner mandibular barbel length 44.7±52.1, outer mandibular barbel length 77.3±106.4. Branchiostegal rays 10 (6) or 11 (7). Gill rakers 4 +11 (1), 4 +13 (1), 5 +10 (1), 5 +12 (2) or 5 +13 (5). Vertebrae 25 +25 = 50 (1), 25 +26 = 51 (3), 26 +25= 51 (5), 26 +26 = 52 (6) or 27 +25 = 52 (5).

Fin ray counts: dorsal I, 7 (12) or I, 8 (1); pectoral I, 8 (1), I, 8, i (9) or I, 9 (3); pelvic i, 5 (11); anal ii, 9 (1), iii, 9 (7), iv, 8 (1), iii, 9, i (1), ii, 10 (1) or iii, 10 (2); caudal 8/9 (13). Dorsal origin nearer tip of snout than caudal ¯exure. Dorsal spine stout, with 0 (2), 2 (1), 3 (3), 4 (2), 5 (1), 6 (1) or 9 (1) irregular serrae posteriorly (®gure 5b). Pectoral spine stout, with 12 (3), 13 (2), 15 (2), 18 (1), 22 (2) or 23 (1) large serrae posteriorly (®gure 5a). Anal origin slightly posterior to adipose origin. Depressed dorsal not reaching adipose ®n. Caudal ®n forked; upper lobe tapering with upper simple principal ray produced into a ®lament, lower lobe rounded posteriorly.

Males with elongate genital papilla reaching to origin of anal ®n. Anus separated from genital appendages of both sexes by 4.3±5.9% SL.

Colour. Dorsal surface of head and body uniform light grey to grey (live or freshly dead specimens have a yellowish hue which fades in preserved specimens), without a humeral spot, lateral line cream to yellow; ventral surfaces of head and body dirty white; adipose ®n and ®n rays of all ®ns grey; inter-radial membranes of all ®ns dirty yellow.

Ecology. Hemibagrus velox , like other similar species in the H. planiceps `group’ ( Ng and Ng, 1995) only occurs in the upper stretches of large rivers. They prefer clear, fast-ōwing waters with a rocky or sandy substrate. Other ®shes syntopic with H. velox include Cyprinidae : L obocheilus cf. bo ( Popta, 1904), Mystacoleucas marginatus (Valenciennes in Cuvier and Valenciennes, 1842), Osteochilus waandersii (Bleeker, 1852) ; Cobitidae : Acantopsis cf. dialuzona van Hasselt, 1823, Botia reversa Roberts, 1989 ; Akysidae : Akysis macronema Bleeker, 1860 ; Sisoridae : Bagarius yarrelli ( Sykes, 1839) and Glyptothorax platypogon (Valenciennes, in Cuvier and Valenciennes, 1840).

Etymology. From the Latin velox , meaning fast. The name refers to its habitat (fast-ōwing streams and rivers) and is used as an adjective.

Remarks. Ng and Ng (1995) provided a brief review of the taxonomy of Sundaic Hemibagrus in which they recognized four di erent`groups’. The`group’ consisting of H. planiceps and allied species, is characterized by its members having an elongate body with a high vertebral count (47±51), a body with no midaxial streak and the longest dorsal-®n ray not, or only just reaching the beginning of the adipose ®n. The nominal species placed in this group include H. planiceps Valenciennes , in Cuvier and Valenciennes, 1840, H. anisurus Valenciennes , in Cuvier and Valenciennes, 1840, H. ¯avus Bleeker, 1846, H. bongan Popta, 1904 and H. gracilis Ng and Ng, 1995 . The synonymy of H. planiceps has been discussed by Ng and Ng (1995) and Roberts (1993); H. ¯avus and H. anisurus are treated as subjective synonyms of H. planiceps . Ng and Ng (1995) have suggested that H. bongan is a valid species and morphological analysis of Bornean specimens by the second author (unpublished data) indicates that this may well be the case. Hemibagrus bongan di ers from its congeners in lacking (vs presence of) the simple principal ray of the upper lobe of the caudal ®n, which extends into a ®lament. The revalidation of H. bongan , however, will be dealt with in another paper and pending a more detailed treatment, we treat H. bongan as a valid species.

Hemibagrus velox can be di erentiated from H. planiceps in having a more slender caudal peduncle (6.2±7.5% SL vs 7.4±8.6), a relatively longer genital papilla in the males (reaching anal origin, vs not reaching; ®gure 3), the upper lobe of the caudal ®n regularly tapering (vs upper lobe rounded posteriorly), more closely set eyes (interorbital distance 29.4±33.9% HL vs 33.9±37.3), longer maxillary barbels (198.3±238.2% HL vs 147.5±207.8), more vertebrae (50±52 vs 47±49) and more branchiostegal rays (10±11 vs 8±10) (data of H. planiceps from material listed).

Hemibagrus velox di ers from H. gracilis in having a longer snout (33.3±38.9% HL vs 26.8±34.4), a relatively longer genital papilla in the males (reaching anal origin, vs not reaching; ®gure 4), the genital papilla located nearer the anus (anus separated from genital papilla by a distance of 4.3±5.9% SL vs 5.4±7.6) and irregular (vs regular) serrations on the posterior edge of the dorsal spine (®gure 4b) (data of H. gracilis from material listed).

Hemibagrus velox has a relatively longer genital papilla in the males (reaching anal origin, vs not reaching, ®gure 3), the upper lobe of the caudal ®n regularly tapering with upper simple principal ray produced into a ®lament (vs upper lobe rounded posteriorly with upper simple principal ray not produced into a ®lament), shorter maxillary (198.3±238.2% HL vs 230.8±282.5) and inner mandibular (44.7±52.1% HL vs 53.6±88.4) barbels compared to H. bongan (data of H. bongan from material listed).

Some of the morphometric characters (e.g. snout length and length of maxillary barbels) used to separate H. velox from its congeners overlap slightly. This is due to the state of preservation of some of the older material and the fact that Hemibagrus species show a certain amount of plasticity ( Kottelat and Lim, 1995a), particularly in morphometrics such as the dorsal to adipose distance and eye diameter.