Schistura maejotigrina, Suvarnaraksha, 2012

Suvarnaraksha, Apinun, 2012, Schistura maejotigrina, a new stream loach (Pisces: Nemacheilidae) from northern Thailand, Zootaxa 3586, pp. 131-137 : 132-135

Schistura maejotigrina sp. nov.

Maejo Tiger Stream Loach

( Fig. 1)

Holotype. MARNM: 002435, male, 53.0 mm SL, 69.6 mm TL, Mae Abb, near water fall and terraced rice fields, 822 m above mean sea level, 18°17'55.2''N, 98°10'29.9''E, tributary of Ping River , Maechaem River system, northern Chao Phraya River basin, Maechaem District, Chiang Mai Province, Thailand, A. Suvarnaraksha, J. Keereelang, K. Talao and S. Suvarn, 19 January 2008.

Paratypes. MARNM: 002436, 39 exs., 28.0– 47.5 mm SL, 34.0– 54.5 mm TL, NIFI: 04551 , 5 exs., 29.0–34.0 mm SL, 36.0–38.0 mm TL, and UF 183767 , 5 ex., 28.0–38.0 mm SL, 35.0–46.0 mm TL; same data as holotype .

Diagnosis. A species of Schistura distinguishable from all other species by unique color pattern consisting of 21–25 dark brown tiger-stripe bars on side of body, bars not reaching venter ( Fig. 1). Head short, 4.1–5.4 times in standard length. Interorbital width 48.1% HL (10.1% SL). Pelvic-fin length 97.0% HL (20.3% SL), approximately equal to head length; length of caudal peduncle 44.8% HL (9.3% SL). Dorsal fin with 4 simple rays and 6½ or 7½ branched rays.

Description. Morphological data are given in Tables 1–4. A medium-sized species (largest 69.6 mm in TL, holotype) compared to other species of Schistura with moderately elongated body, cylindrical anteriorly to origin of dorsal fin, slightly compressed thereafter; head slightly depressed; snout obtuse ( Fig. 2). Mouth semi-circular; lips thin, upper lip without small medial incision, lower lip with deep medial incision; anterior nostril pierced, prolonged as a filament. Eyes small, 2.3–5.5% SL (mean 3.7, S.D. 0.88), diameter smaller than interorbital width; inner maxillary barbel shorter than outer, outer maxillary barbel longer than mandibulary barbel, extending to margin of eye; processus dentiformis present on upper jaw; complete lateral line extending to caudal-fin base; cephalic lateral-line system with 3 supraorbital, 5+5 infraorbital, 7 preoperculomandibular and 4 supratemporal pores, 2 mandibular pores; iii 6½–7½ branched dorsal-fin rays; 10–11 pectoral-fin rays; 8–9 pelvic-fin rays; iii 5 anal-fin rays; 7–9 upper and 7–9 lower branched caudal rays; 12 abdominal vertebrae and 20 caudal vertebrae.

Dorsal fin about half way between tip of snout and caudal-fin base; distal margin of dorsal fin slightly convex; pelvic-fin origin slightly before origin of dorsal fin, anal fin at three-quarters of SL, reaching base of caudal fin when depressed; pectoral fin reaches two-thirds of distance to pelvic-fin origin, pelvic fin does not reach anus; axillary pelvic lobe present; caudal fin emarginate, lobes rounded; weakly developed adipose crest on caudal peduncle. Body covered by small embedded scales. Anus closer to anal fin than to pelvic-fin origin. Intestine turns sharply posteriorly at stomach-outlet with small loop behind the stomach (Fig. 3a).

Coloration. Live specimens light yellowish-brown with 21–25 black, irregular tiger-stripe bars and with wavy black stripe on upper side, above lateral line, extending under dorsal fin. Preserved specimens creamy white with black stripe and bars; bars thinner above lateral line, without reaching venter except on caudal peduncle; head and snout with scattered dark-brown spots; dorsal fin with one black spot at base of simple dorsal ray; black bar at caudal-fin base incomplete, with small blotch dorsally at origin of fin, bar extends from middle of upper caudal lobe to middle of lower caudal lobe; pectoral, pelvic and anal fins hyaline, caudal fin with scattered dark spots. Lower lip without black marks.

% Standard length % Head length

Holotype Range Mean SD Holotype Range Mean SD Total length 122.7 109.1–130.1 123.1 4.02

Lateral head length 21.3 16.9–24.3 21.0 1.62

Predorsal length 50.4 41.4–59.2 52.9 3.30

Prepelvic length 48.7 37.3–57.2 51.9 3.32

Preanal length 81.9 67.9–85.8 78.7 3.57

Body depth 14.7 14.3–19.6 16.6 1.20 68.9 66.7–94.1 79.5 7.0 Depth of caudal peduncle 17.4 8.6–13.5 11.5 1.11 81.4 46.2–64.7 55.0 4.7 Length of caudal peduncle 10.3 6.3–16.3 9.3 1.81 48.1 22.8–82.5 44.8 10.3 Snout length 8.7 6.3–15.9 9.3 1.56 40.7 30.3–58.8 43.8 6.4 Maximum head width 16.1 12.4–16.9 14.9 1.05 75.7 60.0–83.3 71.2 5.9

Eye diameter 3.9 2.3–5.5 3.7 0.88 18.1 11.1–25.0 17.6 3.9 Interorbital width 9.0 6.3–12.5 10.1 1.34 42.0 28.2–61.5 48.1 7.0 Pelvic-fin length 20.5 18.1–22.3 20.3 1.29 96.2 79.3–113.2 97.0 8.4 Pectoral-fin length 22.8 17.3–25.9 22.1 1.64 107.1 92.3–122.2 105.5 7.1 Head depth at occiput 13.1 8.6–15.5 11.9 1.10 61.5 46.2–69.2 56.7 5.1 Pre-pectoral length 20.5 15.9–23.0 20.1 1.80 96.3 76.9–112.5 96.1 9.2

Sexual dimorphism. Males have a suborbital flap (Fig. 3b) and numerous tubercles on the pectoral fin in the breeding season.

Habitat. Specimens were collected from Mae Abb (18°17'55.2''N, 098°10'29.9''E), a stream near a waterfall and terraced rice fields. Elevation is 822 m above mean sea level. Mae Abb is a tributary of Ping River, in the northern Chao Phraya River basin, Maechaem District, Chiang Mai Province. The area has a mean annual rainfall of over 145 cm. Specimens were collected over substrates of mixed gravel, mud and sand in fast flowing, clear water, The catchment of this tributary is endowed with numerous torrential hill streams and vegetation cover. Vegetation cover is comprised of semi-evergreen, plantations and agricultural fields (mainly cabbages and tomatoes). On 19 January 2008, the water temperature was 17° C, air temperature 20.5° C, pH 7.7, ammonia and nitrite 0 ppm, dissolved oxygen 8 mg /l, calcium 80 ppm, magnesium 24 ppm, and conductivity 20 µS. Stream width was 3–4 meters and water depth 37.5 cm. All specimens were collected during the day time.

Distribution. Schistura maejotigrina is known only from the Maechaem River system, Ping River drainage, northern Chao Phraya River basin, Maechaem District, Chiang Mai Province, Thailand (Fig. 4). Other species collected at the type locality (Fig. 5) include the nemacheilids: Schistura breviceps , S. pridii , S. spilota ; a sisorid: Oreoglanis siamensis ; cyprinids: Devario sp. , Scaphiodonichthys burmanicus , and a channid: Channa gachua .

Etymology. The specific epithet, maejotigrina , an adjective, refers to the 77 th Maejo University Anniversary and the presence of the irregular tiger-stripe bars on the side of the body.