Bangana brevirostris, Liu, Kai & Zhou, Wei, 2009

Liu, Kai & Zhou, Wei, 2009, Bangana brevirostris, a new species of cyprinid fish (Teleostei: Cypriniformes) from the Lancang-Jiang (Upper Mekong River) drainage in Yunnan, Southwest China, Zootaxa 1980, pp. 61-68 : 62-65

Bangana brevirostris , sp. nov.

( Figures 1 , 2 A)

Holotype: SWFC 0512080, 93.7mm SL, China: Yunnan: Boluo River, a stream tributary of the Luosuo-Jiang (first-order tributary of the Lancang-Jiang belonging to the Mekong River basin) at Boluo Village (22°37΄N, 101°18΄E) of Yixiang Town in Puer City; collected by W. Zhou in 9 Dec. 2005.

Paratypes: SWFC 0512071-0512079, SWFC 0512081-0512088, 17 ex., 81.1–95.6mm SL, same data as holotype.

Diagnosis: Bangana brevirostris can be distinguished from all congeners from China and lower Mekong River outside of China by the following combination of characters: mental groove short and shallow, anteriorly connected with the end of the postlabial groove, terminating beneath the anterior margin of the eye; a pair of minute rostral barbels, situated below anterior end of shallow furrow on side of snout; dorsal fin with 12–13 branched rays; 42–44 lateral-line scales; eye large, its diameter 28.1–32.9 % HL; snout short, its length 25.5–32.7 % HL.

Description: Morphometric data for the holotype and 17 paratypes are given in Table 1 . Dorsal-fin rays iii, 12–13; pectoral-fin rays i, 16–17; pelvic-fin rays i, 8; anal-fin rays iii, 5. Lateral-line scales 42–44; scale rows between lateral line and dorsal-fin origin 7; scale rows between lateral line and pelvic-fin origin 6; predorsal scales 13–14; circumpeduncular scales 20.

Body elongate, slightly compressed laterally; highest point of body at dorsal-fin origin; abdomen complanate, with small scales. Snout obtuse, rounded, with a shallow furrow running along anteroventral border of lachrymal to lateral extremity of rostral fold. Postorbital length of head greater than snout length. Head moderately compressed laterally, head length greater than head depth, head depth greater than head width. Mouth inferior, gape arch-shaped. Rostral fold curved ventrally, covering base of upper lip, separated from upper lip by a deep groove, disconnected from lower lip around corners of mouth, its margin and surface smooth. Upper jaw fully enclosed by upper lip. Upper lip smooth, laterally connected with lower lip. Lower lip anteriorly separated from lower jaw by a transverse groove, with a free anterior margin containing numerous papillae. Anterior margin of lower jaw exposed, osseous, with a sharp cutting edge. Postlabial groove present along entire anterior margin of lower lip, but interrupted by thin dissepiment at sides of lower jaw.

Mental groove short, shallow, anteriorly connected with end of postlabial groove, terminating vertically beneath anterior margin of eye. Eye relatively large (eye diameter 28.1–32.9 % HL); upper edge of eye approaching dorsal contour. Interorbital broad, flat, its width greater than snout length. A minute pair of rostral barbels situated below anterior end of shallow furrow on side of snout. Scales moderately large, smaller on breast. Pelvic fin with an elongate axillary scale at its outer base. Lateral line complete, its forepart curving ventrally slightly, then extending to central axis of caudal peduncle. Caudal-peduncle length slightly greater than its depth.

Holotype Paratypes (17)

Min Max Mean SD Last unbranched ray of dorsal fin not ossified. Distal margin of dorsal fin curved. Dorsal-fin origin closer to snout tip than to caudal-fin base. Distance from snout tip to origin of dorsal fin greater than that from end of dorsal-fin base to caudal-fin base. Pectoral fin pointed, shorter than head length. Pectoral-fin origin close to gill opening. Posterior end of pectoral fin not reaching pelvic-fin origin. Pelvic fin extending horizontally, its insertion under fourth or fifth branched dorsal rays, further from snout tip than from anal-fin base. Posterior end of pelvic fin separated from anus by 3–4 scales. Distal margin of anal fin slightly curved. Posterior end of anal fin nearly reaching caudal-fin base. Distance of anal-fin origin to caudal-fin base equal to or slightly less than that from anal-fin origin to pelvic-fin origin. Anal-fin origin separated from anus by 2–3 scales. Caudal fin deeply forked, its shortest ray 25.0–33.3 % length of its longest one; tips of caudal-fin lobes pointed, upper lobe almost equal to lower one.

Coloration in 75% ethanol: Body brown dorsally, grayish laterally, becoming yellowish ventrally. Dorsal and caudal fins dusky; pectoral and pelvic fins yellowish; anal fin gray and yellow. An indistinct longitudinal black stripe extending along first scale row above lateral line on flank from below dorsal-fin origin to caudal-fin base. Each scale with a crescentic black bar along posterior marign of its exposed portion, forming a reticular framework, more obvious above first scale row below lateral line.

Distribution: Bangana brevirostris is presently known only from the Luosuo-Jiang, a first-order stream of the Lancang-Jiang (Mekong River basin) in Puer City and Xishuangbanna Prefecture, southern Yunnan, Southwest China (Fig. 3).

Etymology: The species name is derived from the Latin brevis (short) and rostrum (snout), a reference to the

Figures

FIGURE 1. Bangana brevirostris, holotype, SWFC 0512080, 93.7 mm SL; China: Lancang-Jiang. Lateral view.

FIGURE 2. Ventral view of oromandibular structures in: (A) Bangana brevirostris, holotype, SWFC 0 512080, 93.7 mm; China: Lancang-Jiang. (B) B. tonkinensis, KIZ 846309, 59.1 mm SL; China: Lixian-Jiang. (C) B. devdevi, KIZ 8310056, 130.6 mm SL; China: Irrawaddy River. (D) B. lemassoni, KIZ 2007001755, 215.0 mm SL; China: Lixian-Jiang. dt = dissepiment; lj = lower jaw; ll = lower lip; mg = mental groove; pg = postlabial groove; rf = rostral fold.

Tables

TABLE 1. Morphometric data for the holotype and 17 paratypes of Bangana brevirostris.

SL (mm)	93.7	81.1	95.6	87.5	4.4
HL (mm)	23.1	21.1	25.1	22.6	0.9
HD (mm)	16.5	15.1	17.6	15.8	0.7
HW (mm)	13.2	11.7	14.9	12.7	0.7
Percentage SL
Body depth	23.1	23.1	25.9	24.3	0.9
Head length	24.7	24.7	28.0	25.9	0.9
Length of caudal peduncle	14.3	11.9	15.0	13.6	0.9
Depth of caudal peduncle	10.7	9.9	12.1	10.6	0.5
Dorsal-fin length	24.3	22.9	25.3	20.8	0.8
Pectoral-fin length	19.5	17.5	21.2	18.8	0.8
Pelvic-fin length	15.9	15.7	18.6	17.1	0.8
Anal-fin length	18.1	16.3	18.9	17.6	0.6
Caudal-fin length	26.5	26.5	32.9	29.1	1.8
Predorsal length	46.2	44.1	50.3	46.7	1.4
Prepectoral length	24.4	24.4	27.4	26.0	0.9
Prepelvic length	53.9	53.0	57.1	54.7	1.1
Preanal length	77.8	76.3	83.2	79.2	1.7
Length from dorsal-fin origin to caudal-fin base	54.9	52.3	59.0	55.1	1.7
Length from the end of dorsal-fin base to caudal-fin base	34.5	32.7	37.1	35.3	1.1
Length from anal-fin origin to pelvic-fin origin	23.6	23.6	27.7	25.4	1.2
Length from anal-fin origin to caudal-fin base	24.8	21.4	24.8	23.4	1.1
Percentage of HL
Snout length	27.7	25.5	32.7	28.7	2.1
Eye diameter	30.7	28.1	32.9	30.6	1.4
Interorbital width	34.6	32.2	38.6	35.0	1.4
Postorbital length of head	42.0	39.2	46.5	41.7	2.0