Schistura syngkai, Choudhury & Mukhim & Dey & Warbah & Sarma, 2019

Choudhury, Hrishikesh, Mukhim, D. Khlur B., Dey, Abhinit, Warbah, Deisakee P. & Sarma, Dandadhar, 2019, Schistura syngkai, a new fish species (Teleostei: Nemacheilidae) from Meghalaya northeast India, Zootaxa 4701 (2), pp. 185-191 : 186-188

Schistura syngkai , new species

( Fig. 1 , Table 1 )

Holotype. ZSI FF 8317, 42.1 mm SL; India: Meghalaya: West Khasi Hills District: Twahdidoh Stream of Wahblei River (Surma-Meghna drainage) near Seinduli village , 25°39ʹ32ʺ N 91°08ʹ22ʺ E; 1100 m asl; D. K. B. Mukhim, June 2017.

Paratypes. GUMF 304 /6, 6 specimens, 26.8–43.0 mm SL; same data as holotype .

Diagnosis. Schistura syngkai is distinguished from all other Indian congeners in having (in combination) a unique colour pattern in the form of a prominent dark-brown to black mid-lateral stripe about an eye diameter or more in width, overlain on 12–18 vertically-elongate black blotches on a golden-brown to amber (fading to light brown or pale beige in preservative) body. Additionally, the species is diagnosed in having 11–17 dark-brown or greyish saddles, the dorsal-fin origin posterior or nearly opposite to pelvic-fin origin, an incomplete lateral line, and a slightly emarginate caudal fin.

Description. A moderately elongate loach with body nearly oval in cross-section, compressed caudad. Head slightly depressed at nape, with an arched anterior profile up to nares. Dorsal body profile gently rising up to slightly ahead of dorsal-fin origin, following a descent through dorsal-fin base, nearly straight or (sometimes) ascending thereafter up to caudal-fin base. Ventral profile nearly straight, (rarely) arched up to pelvic-fin base, following a descent up to anal-fin origin, then concavely arched up to caudal-fin base. Short and shallow adipose crests along dorsal and ventral midlines of caudal peduncle.

Mouth arched, nearly semi-circular, about 1.3–1.5 times wider than long, with thick, fleshy lips; upper lip with inconspicuous median incision and shallow, thin wrinkles; lower lip with narrow median interruption, both halves not forming ‘cushions’, oriented at an obtuse angle, with 1–5 sulci medially and shallow wrinkles (or sometimes plain, without wrinkles) laterally; tip of lower jaw exposed with mouth closed ( Fig. 2a ). Processus dentiformis present on upper jaw, with corresponding shallow median concavity on lower jaw. Anterior nostril pierced in front of a long, pointed, tube-like flap, reaching anterior margin of eye. Barbels in three pairs: inner rostral barbel reaching gape of mouth; outer rostral reaching slightly beyond vertical through anterior margin of orbit; maxillary barbel reaching ¾ distance between gape of mouth and pectoral-fin base.

Dorsal fin with 4 (7*) simple and 7½ (4)–8½ (3*) branched rays; its origin nearly opposite or behind pelvic fin. Anal fin with 3 (7*) simple and 5½ (7*) branched rays; adpressed fin not reaching hypural flexure. Pectoral fin with 1 (7*) simple and 9 (1)–10 (6*) branched rays; adpressed fin reaching ⅔ distance between its origin and pelvic fin. Pelvic fin with 1 (7*) simple and 7 (7*) branched rays; adpressed fin not reaching anus. Caudal fin with 8 + 8 (7*) branched rays, slightly emarginate, lobes rounded, upper lobe slightly longer than lower. Anus situated about 1½ eye diameters ahead of anal-fin origin.

Body covered with minute, deeply-embedded cycloid scales, except ventrally between paired fins. Lateral line incomplete (often discontinuous) with 19–42 pores, ending slightly ahead of pelvic fin or below origin of fourth branched ray of dorsal fin. Cephalic lateral line system with 5–8 supraorbital, 3 + 9–10 infraorbital, 9–10 preoperculomandibular and 3 supratemporal pores. Intestine with a loop behind stomach ( Fig. 2b ). Air bladder encased in an ossified capsule, its halves connected by a manubrium; a small, free posterior chamber present ( Fig. 2c ). Axillary pelvic lobe small, inconspicuous.

Coloration. In preservative: Anterior lateral one-fifth of body light brown to pale beige dorsally, fading to cream or pale white ventrally. Dorsal region of head up to level of infraorbital-pore canal darker brown than body, sometimes greyish, except lighter nasal flaps; cream to pale white ventrally. A prominent dark brown to black midlateral stripe about an eye diameter or more in width, overlain on 12–18 vertically-elongate black blotches, starting immediately behind opercular margin and extending up to caudal base. Stripe often discontinuous or interrupted in specimens below 35 mm SL. Saddles 11–17, not very contrasted, dark-brown (or greyish black), equal to or wider than interspaces, (rarely) extending ventrally to interconnect with lateral blotches; predorsal saddles mostly broken into irregular blotches. An oblique black stripe from tip of snout to anterior margin of eye. Rostral barbels greyish dorsally, cream ventrally; maxillary barbel cream. Caudal bar pattern consisting of a medial black bar occupying about two-thirds of caudal-fin depth, connected with mid-lateral stripe or separated by a narrow gap, and an oblique or oval blotch over the dorsal procurrent rays. All fins hyaline, except dorsal fin, which has a prominent black blotch proximally just above the fin base covering last unbranched ray, first branched ray and interradial membrane connecting them, and two rows of spots: first medially along unbranched and first branching points of branched rays, and second along distal one-third of branched rays; distal two-thirds of unbranched and first branched pectoral-fin rays sometimes blackish; caudal-fin with two irregular vertical rows of black or brown spots on fin rays.

In life: Similar to that described above, except golden-brown to amber background dorso-laterally, fading to pale yellow or cream ventrally. Fins amber or golden brown. All markings black. Anterior margin of opercular bone often with a faint, greyish-black ‘comma-like’ punctuation. Rostral barbels reddish brown dorsally. When stressed (e.g., immediately after collection), anterior half of the mid-lateral stripe may appear faded ( Fig. 1c ).

Sexual dimorphism. No sexually dimorphic characters (viz., modified pectoral-fin rays, suborbital flap/slit, aggregation of tubercles, unculiferous pads or puffed cheeks) observed.

Distribution and habitat. Presently, the new species is known only from its type locality, near Seinduli (village) in West Khasi Hills District, Meghalaya ( Fig. 3 ). The Twahdidoh stream is a right bank tributary to the Wahblei River and itself a complex of several streamlets flowing through tropical evergreen forest interspersed with conifers. The new species was collected adjacent to a rice paddy in its lower stretch. The stream has a muddy bottom with stretches of pebbles and rocks, and the habitat is covered with dense perennial grasses ( Fig. 4 ).

Etymology. From the Khasi (an ethnic community of Meghalaya) word ‘ Syngkai ’ meaning a loach-like fish. A noun in apposition.

Figures

FIGURE 1. Schistura syngkai; India: Meghalaya: Barak drainage: Wahblei River — a, b, ZSI FF 8317, holotype, 42.1 mm SL, lateral and dorsal views; and c, live specimen (not preserved), about 44 mm SL, immediately after collection.

FIGURE 2. a, lip morphology; b, intestinal coiling pattern; and c, air bladder of Schistura syngkai; GUMF 304/6, paratype, 41.6 mm SL. Scale bars 1mm.

FIGURE 3. Map showing the type locality (filled circle) of Schistura syngkai.

FIGURE 4. The Twahdidoh stream adjacent to a rice paddy near Seinduli village, the habitat of Schistura syngkai.