Physoschistura tigrinum, R, L O K E S H W O, 2012

R, L O K E S H W O, 2012, A new loach of the genus Physoschistura Bănărescu & Nalbant (Teleostei: Nemacheilidae) from Chindwin basin, Manipur, India, Zootaxa 3586, pp. 95-102 : 97-100

Physoschistura tigrinum , new species

( Fig. 1 )

Type material. Holotype. MUMF 11051, 73.6 mm SL, male; India: Manipur: Ukhrul district: Phungrei, Changa River (the Chindwin drainage); 25°12´26˝ N 94°31´35˝E; Kingson, December 2004.

Paratypes. MUMF 11050, 72.8 mm SL, female & MUMF 11052–11053, 2, 73.0– 73.2 mm SL, males; same data as holotype; one paratype ( MUMF 11053, 73.2 mm SL) was dissected for study of the intestine and air bladder.

Diagnosis. A large Physoschistura reaching 73.6 mm SL, distinguished from its congeners in having the following combination of characters: 12–14 irregular light reddish brown bars (few become broken and forming blotches) on side of body; 5–6 reddish brown irregular saddles on back; lateral line complete with 90–94 pores; 9+8 branched caudal fin rays; axillary pelvic-fin lobe present but not prominent; male with suborbital flap; 10 pores in preoperculomandibular canal.

Description. Counts and measurements are in Table 1 . Body elongated and stout. Dorsal profile gently arched, elevating evenly from tip of snout up to dorsal-fin origin, sloping to the point vertical to anal-fin origin and then nearly horizontal to caudal-fin origin. Body oval in cross section anteriorly, becomes slightly compressed and then more compressed posteriorly. Ventral profile of body more or less straight throughout length. Head slightly depressed and almost as broad as high at nape. Snout length almost half head length, almost as long as broad at nares and about twice eye diameter.

Dorsal fin with three simple and 9½ branched rays, articulating nearer to tip of snout (predorsal length, 45.0–47.0% of SL) than to caudal-fin base, in advance of pelvic-fin origin; distal margin slightly convex. Anal fin with three simple and 5½ branched rays. Pectoral fin with 11 rays, reaching about half distance to pelvic-fin base. Pelvic fin with 8 rays, origin below base of 3rd or 4th branched dorsal-fin ray, reaching about midway to anal-fin origin; distal margin of pelvic fin reaching vent when adpressed. Axillary pelvic-fin lobe present and is prominent. Caudal fin with 9+8 branched rays, slightly forked, lobes equal, upper lobe 1.3–1.5 times longer than median rays. Caudal peduncle 1.4–1.7 times longer than deep, with low dorsal and ventral adipose crests on posterior half. Largest recorded size 73.6 mm SL (MUMF 11051).

Body covered with partly overlapping minute scales, except between base of pectoral fin and belly where scales are absent. Lateral line complete, straight, with 90–94 pores. Cephalic lateral-line system with 12 supraorbital, 3+8 infraorbital, 10 preoperculomandibular and three supratemporal pores. Unculi present on lips, barbels, throat, snout, interorbital area, and pectoral and pelvic rays.

Anterior nostril pierced on anterior side of low pointed flap-like tube. Mouth strongly arched, 1.4–1.5 times wider than length. Lips fleshy; upper lip finely pleated, with a median incision. Lower lip with two lateral, broadly triangular pads separated by a wide median furrow ( Fig. 2 A). Processus dentiformis present, not prominent. No median notch in lower jaw. Inner rostral barbel reaching to vertical of nostril or maxillary barbel base; outer one more elongated, reaching vertical below middle of eye. Maxillary barbel reaching to vertical of occiput. Free posterior chamber of air bladder present, not encapsulated, slightly conical ( Fig. 3 A). Intestine with bend immediately behind stomach ( Fig. 4 A).

Sexual dimorphism. Male with prominent suborbital flap.

Color. In 10% formalin: body light yellowish with 12–14 irregular light reddish brown bars on the side/flank, extending from upper side, crossing lateral line, reaching level of pectoral fin. Some bars broken, forming irregular blotches. Dorsal and lateral aspect of head mottled with irregular reddish brown spots. Dorsal surface of body with 5–6 reddish brown saddles of irregular shape. Dorsal-fin base with two black spots; first one larger, extending from first simple ray to first branched ray; second extending from between second and third branched rays to base of fourth branched ray. Caudal-fin base with prominent dark brown bar subtended at top and bottom by black spots. Middle of caudal fin with irregular elongated rows of dark brown spots. Branched pectoral-fin rays with 3 transverse rows of brown spots, one at base, one in middle and one in subterminal region. Outer rostral barbel with black spot at base.

Distribution. India: Manipur: Ukhrul district: Phungrei, Changa River, tributary of Tizu River (Chindwin drainage) ( Fig. 5 ).

Etymology. The species is named for the tiger-like bars on the body.

Figures

FIGURE 1. Physoschistura tigrinum, n. sp.: lateral aspect of (A) holotype, MUMF 11051, 73.6 mm SL, male; (B) paratype, MUMF 11053, 73.2 mm SL, female; (C) dorsal aspect of holotype.

FIGURE 2. Lip structure of (A) Physoschistura tigrinum and (B) P. prashadi.

FIGURE 3. Air bladder of (A) Physoschistura tigrinum and (B) P. prashadi showing free posterior chambers.

FIGURE 4. Coiling pattern of intestine of (A) Physoschistura tigrinum and (B) P. prashadi.

FIGURE 5. Map showing type locality of Physoschistura tigrinum.

Tables

TABLE 1. Morphometric data of Physoschistura tigrinum.

% SL Body depth Head depth at nape Lateral head length	Holotype MUMF 11051 17.0 13.0 22.0	Paratypes MUMF 11050 18.0 13.0 23.0	MUMF 11052 19.0 14.0 22.0	MUMF 11053 17.5 13.3 22.5
Dorsal head length Head depth at eye	19.0 10.0	19.0 11.0	20.0 12.0	19.7 10.5
Caudal-peduncle length Caudal-peduncle height Predorsal length Prepelvic length	15.0 9.8 47.0 48.0	16.0 9.8 47.0 51.0	15.0 11.0 45.0 53.0	15.4 10.0 45.7 50.5
Preanus length Preanal length	67.0 73.0	69.0 76.0	72.0 79.0	68.5 75.0
Dorsal-fin height Pelvic-fin length Anal-fin depth Pectoral-fin length	16.0 16.0 17.5 19.0	15.0 18.0 16.5 20.0	17.0 17.0 17.0 18.0	16.0 16.5 17.0 18.5
Max. head width at cheek Head width (at nares)	12.0 9.5	14.0 8.4	14.0 9.5	13.0 9.0
Body width at anal-fin origin Body width at dorsal-fin origin % HL Snout length	7.1 12.0 47.4	8.1 13.0 50.6	7.9 12.0 46.9	7.5 12.4 47.2
Interorbital distance Eye diameter	27.3 23.8	28.5 23.8	29.2 23.9	28.0 23.9
Mouth gape width Lateral length of head Head depth at eye Head depth at nape	35.1 114.0 53.9 68.6	31.2 119.0 58.5 68.8	29.9 112.0 58.3 69.4	33.0 113.5 55.0 68.6
Body depth at dorsal-fin origin Depth of caudal peduncle	90.2 50.4	91.3 50.7	94.4 55.6	92.0 53.6
Length of caudal peduncle Maximum head width Body width at dorsal-fin origin Body width at anal-fin origin	79.2 62.6 59.6 36.5	85.5 70.9 66.0 41.9	77.4 71.1 61.1 40.3	80.2 64.0 60.0 37.6