Schistura andrewi, Solo, Beihrosa & Lalronunga, Samuel, 2014

Solo, Beihrosa & Lalronunga, Samuel, 2014, Schistura andrewi, a new species of loach (Teleostei: Nemacheilidae) from Mizoram, northeastern India, Zootaxa 3860 (3), pp. 253-260 : 254-256

Schistura andrewi , sp. nov.

( Fig. 1 )

Type material. Holotype: PUCMF 14001, 50.5 mm SL; India: Mizoram, Mat River, a tributary of Kaladan River in the vicinity of Serchhip, Serchhip District, 23° 20' 04" N; 92° 50' 01" E; Beihrosa Solo et al. 20 April 2013.

Paratypes: PUCMF 14002 (8), 35.9–44.6 mm SL; MZUBM /F. 140001–140003 (3), 40.1–45.2 mm SL; PUCMF 14003 (4), 36.9–41.3 mm SL (cleared and stained); locality data same as holotype.

Diagnosis. Schistura andrewi differs from other species of the genus from the Kaladan basin and its adjacent basins by having the combination of the following characters: long axillary pelvic lobe; complete lateral line with 82–95 pores; 2 unbranched dorsal and anal fin rays; 6–7 broad, wider than interspace, black bars on the body; 2 rows of black spots horizontally across the dorsal fin; a deeply emarginate caudal fin with 2 vertical rows of black spots across the fin, and 9 + 8 branched caudal fin rays; males with a sub-orbital flap; and intestine looped behind the stomach.

FIGURE. 2. Schistura andrewi ; a) paratype, PUCMF 14002, 43.1 mm SL, ventral view of head; b) paratype, PUCMF 114003, 41.3 mm SL, digestive tract. Scale bars = 1 mm.

Description. Biometric data are given in Table 1 . Body elongate; dorsal profile rising evenly from tip of snout to level of eye, gradually increasing thereafter to dorsal fin origin, then sloping gently to end of caudal peduncle. Body cylindrical anteriorly to origin of dorsal fin, becoming increasingly compressed thereafter. Head long, depressed; snout rounded. Eyes ovoid, large, positioned near top of head, slightly anterior towards snout, not visible in ventral view.

Anterior nostril pierced anteriorly, a flap-like tube, not reaching eye, nearer to eye than snout tip. Mouth subterminal, large, moderately arched, its gape (about 2.0–2.4 times) wider than long. Lips thick, fleshy (Fig. 2a), covered by furrows. Upper lip with small median incision. Lower lip with median interruption. No median notch on lower jaw. Processus dentiformis present. Inner rostral barbel extending up to ⅓ of distance between snout tip and anterior rim of orbit, outer rostral barbel extending up to ⅔ of distance between snout tip and anterior rim of orbit; maxillary barbel extending vertical through middle of orbit. Barbels covered with unculi.

Dorsal fin with 2 simple and 8½ (16) branched rays, its origin anterior to pelvic fin insertion; its distal margin convex; last unbranched ray shorter than first branched ray. Pectoral fin sub-acuminate, with 11 (5) or 12 (11) rays, its insertion slightly anterior to posterior edge of opercle, adpressed fin tip reaching midway between its insertion and pelvic fin insertion. Pelvic fin sub-acuminate, shorter than head length, with 8 (16) rays; its insertion posterior to dorsal fin origin, midway between snout tip and caudal fin base, adpressed fin tip reaching anus. Axillary pelvic lobe present at pelvic fin base. Anal fin sub-acuminate with 2 simple and 5½ (16) branched rays, its origin slightly closer to caudal fin base than pelvic fin insertion. Caudal fin branched rays 9 + 8 (16). Caudal fin deeply emarginate, its lobes sub-equal. Caudal peduncle 1.2 times longer than deep, with very low or no adipose crest.

Entire body covered by minute cycloid scales, deeply embedded, sparse on chest and belly, no scales on head and cheeks. Lateral line complete with 82–95 pores. Cephalic lateral-line system with 8 supraorbital, 4+9/10 infraorbital, 9 pre-operculomandibular and 3 supratemporal pores. Intestine with a large loop behind stomach (Fig. 2b)

Vertebrae (abdominal + caudal): 21+12 = 34 (3) or 20 + 12 = 33 (1).

Sexual dimorphism. A prominent sub-orbital flap present in males.

Coloration. In 70% alcohol: Body light-yellowish brown with 6–7 wide black bars, usually wider than interspaces (typically 2–3 pre-dorsal, 2 sub-dorsal and 2 post-dorsal); all bars coalesces dorsally and reaching to level of pelvic fin base ventrally; posteriormost bar coalesce ventrally. Black basicaudal bar complete and well marked. Dorsal surface of head dark brown. Dorsal fin hyaline with a black blotch at base, covering simple and first branched rays; 2 rows of black spots on rays horizontally across the fin; caudal fin hyaline with 2 rows of black spots on rays vertically across the fin. Pectoral, pelvic and anal fin hyaline, with dark markings on inter-radial membrane.

Fresh specimens are similar to preserved specimen except for reddish coloration on the caudal peduncle region, dorsal and ventral portions of the caudal fin near the basicaudal bar.

Etymology. The species is named after Andrew Arunava Rao who extends his help to the authors for documentation of fishes in Mizoram. It is a noun in apposition.

Distribution and habitat. The species has been collected only from the Mat River, tributary of Kaladan River, Mizoram, India ( Fig. 3 ). Specimens were collected from a small pool in slow-flowing water. The substrate was composed of sand, gravel and rocks. The species was found associated with Schistura nebeshwari , Olyra sp. and Garra spp.

Figures

FIGURE 1. Schistura andrewi; a) holotype, PUCMF 14001, 50.5 mm SL; lateral, dorsal and ventral view.

FIGURE 3. Map showing the collection locality of Schistura andrewi (circle); circle indicates more than a single locality.

Tables

TABLE 1. Biometric data for Schistura andrewi (n = 16). Ranges include values of holotype.

	holotype	range	mean	SD
Standard length (mm)	50.5	35.9–50.5
In % standard length
Dorsal head length	19.8	19.6–21.2	20.6	0.6
Lateral head length	23.4	21.5–24.5	22.9	0.7
Pre-dorsal length	50.7	49.9–53.6	51.7	1.0
Pre-pelvic length	55.8	50.7–57.1	53.3	1.8
Pre-anus length	71.7	69.1–73.3	71.7	1.4
Pre-anal length	77.8	74.7–80.2	77.6	1.3
Head depth at occiput	13.1	11.8–13.6	12.6	0.5
Body depth at dorsal fin	18.8	15.9–18.8	17.3	0.9
Body depth at anal fin	16.0	14.0–16.4	15.1	0.8
Depth of caudal peduncle	13.9	11.7–14.0	12.8	0.6
Length of caudal peduncle	15.8	13.8–16.2	14.8	0.6
Head width at eye	13.1	10.9–13.1	11.9	0.5
Maximum head width	15.4	13.2–15.4	14.2	0.6
Body width at dorsal fin origin	15.6	12.9–15.6	14.3	0.9
Body width at anal fin origin	10.1	8.9–10.5	9.8	0.5
Height of dorsal fin	15.4	14.3–16.9	15.3	0.7
Length of upper caudal fin rays	22.6	20.1–23.1	21.6	0.9
Length of lower caudal fin rays	23.8	21.7–24.2	23.2	0.8
Length of median caudal fin rays	13.3	12.1–14.0	12.8	0.6
Length of anal fin	17.6	15.7–18.1	17.3	0.7
Length of pelvic fin	20.8	17.4–20.8	18.9	0.9
Length of pectoral fin	23.4	19.1–23.5	21.7	1.3
In % dorsal head length
Snout length	34	27–35	32	2.0
Eye diameter	20	20–23	22	1.4
Interorbital width	31	26–33	30	2.1