Pethia poiensis, Shangningam & Vishwanath, 2018

Shangningam, Bungdon & Vishwanath, Waikhom, 2018, Pethia poiensis, a new species of cyprinid fish from the Chindwin Basin of Manipur, India, Zootaxa 4379 (4), pp. 585-593 : 586-590

Pethia poiensis , sp. nov

( Fig. 1 )

Holotype. ZSI FF 7153 , 42.5 mm SL, female; India: Manipur: Ukhrul District, Challou River at Poi Village , 25°17ꞌ N 94°31' E, 3545 ft above sea level; BD Shangningam et al. 30 May 2012.

Paratypes. ZSI FF 7154 (2), 38.0– 42.2 mm SL; MUMF 12093–12101 (9), 36.0– 43.2 mm SL; same data as holotype. Two paratypes, MUMF 12094 &12101, 36.0– 42.6 mm SL, dissected for osteology .

Diagnosis. Pethia poiensis is distinguished from its congeners by the following combination of characters: body with a black humeral spot above 3rd¯4th lateral line scales and a caudal peduncle spot on 16th and 17th lateral series scales; a black mid-lateral stripe along the body; barbels absent; last simple dorsal-fin ray osseous and serrated posteriorly with 16–19 serrae, its length16.2–23.4% SL, the dorsal fin with a black submarginal band and possessing three unbranched and eight branched rays; predorsal scales 9 or 10, pre-anal scales 18, circumpeduncular scales 10 and lateral line incomplete with 7–9 pored scales, 19–20 scales in lateral series.

Description. General body shape as in Figure 1 . Morphometric data for the holotype and 11 paratypes are provided in Table 1. Body elongate, moderately deep, its depth contained in 29.3–38.3 % SL, compressed laterally. Pre-dorsal contour convex, rising gradually up to dorsal-fin origin, thereafter sloping moderately towards caudalfin base. Caudal peduncle elongated, slightly deep, its depth slightly less than its length, concave in both dorsal and ventral profiles. Ventral profile convex up to base of pelvic fin, running almost straight to anal-fin origin towards posterior of anal-fin base, then straight to caudal-fin base.

Head small, laterally compressed, its length 26.6–29.3% SL. Snout rounded, smooth, slightly longer than eye diameter. Eyes large, their diameter 21.2–28.9 % HL, dorso-laterally positioned, closer to the tip of the snout than to the operculum. Mouth small, subterminal, angle of gape almost reaching to vertical through anterior margin of eye. Upper lip relatively thicker and more fleshy than lower lip, lower lip interrupted medially. Barbels absent.

Dorsal fin originating midway between tip of snout and caudal-fin base, opposite pelvic-fin origin, its anterior and posterior corners rounded, last ray reaching to about vertical through end of anal-fin base. Dorsal fin with three simple and eight branched rays, last simple dorsal fin ray as long as first branched ray, strong and serrated posteriorly with 16–19 serrae ( Fig. 2a ). Pectoral fin with one simple and 11 branched rays, its tip rounded, reaching one or two scales anterior to pelvic-fin origin. Pelvic fin with one simple and eight branched rays, its tip rounded, not reaching vent when adpressed. Anal fin with three simple and five branched rays, originating opposite end of dorsal-fin base, distal margin straight with rounded corners. Caudal fin forked, lobes subequal, upper lobe slightly longer with 10+9 principal rays, procurrent rays five (5) or six (7) dorsally and four (2) or five (10) ventrally.

Lateral line incomplete with seven (4), eight (2) or nine (6) pored scales, 19 (2)–20 (10) scales in lateral series, which slightly curves ventrally in the middle of the body. Scales between dorsal-fin origin and lateral-line row 3½, between lateral line and pelvic-fin origin 3. Predorsal scales 9 (8) or 10 (4), pre-anal scales 18, circumpeduncular scales 10. Pelvic axillary scale present, reaching to one-third of adpressed pelvic-fin length.

Osteology. Infraorbital bones 5 (IO1–5); IO3 deep, much broader with greatly elevated margins compared to other bones of the infraorbital series ( Fig. 2b ). Post-epiphysial fontanelle absent ( Fig. 2c ). Pharyngeal teeth 5,3,2 ( Fig. 2d ). Branchiostegal rays 3. Predorsal neural spine 5 (2). First pterygiophore inserted between 9th and 11th vertebrae. Caudal fin with six hypurals and one parhypural ( Fig. 2e ). The last three caudal vertebrae support the caudal fin. Epural free in region between pleurostyle and neural spine of preural centrum. Total number of vertebrae 4+26–27. Gill rakers two on epibranchial, one at angle, and four or five on ceratobranchial.

Coloration. In 10% formalin, dorsum is black to light brown, predorsal midline dark brown. Body background yellowish brown laterally, lower parts of body behind lateral line whitish, snout grey and lower part of head pale yellow. Scales speckled with melanophores on their bases and posterior margins, spots deep, becoming intense dorsally and faint ventrally. Flank with a black stripe along the lateral-line scales; a brown humeral spot above 3rd and 4th lateral-line scales and a caudal peduncle blotch extending over 16th and 17th lateral line scales above the posterior end of the anal-fin base. Abdomen and chest creamy white. Females with light brown humeral spot. Caudal peduncle blotch large and conspicuous. Fins hyaline. Dorsal fin with faint pigmentation representing submarginal dark band. Caudal-fin rays with faint melanophores.

Males with light beige background colour. Dorsum black. Dorsal fin yellowish-green with black submarginal bands, distal margin hyaline. Pelvic, anal and caudal fins hyaline with orange to bright red. Flank with a dark brown stripe along the lateral-line scales with a thin black line in middle.

Distribution. Pethia poiensis is presently known only from the type locality, Challou River at Poi village, Ukhrul district, Manipur state, India ( Fig. 3 ).

Habitat. The type locality, Challou River ( Fig. 4), is swift flowing with a gravel bottom and numerous riffles. Other species collected from the locality include: Amblyceps torrentis, Channa gachua, Garra paralissorhynchus, Mastacembelus armatus, Opsarius barnoides, Psilorhynchus maculatus and Schistura nagaensis .

Etymology. The species is named after Poi, a small hilly village above the type locality, with gratitude for the help extended by residents during our fieldwork in the area.

Figures

FIGURE 1. Pethia poiensis (a) ZSI FF 7153, holotype, 42.5 mm SL; female: (b) MUMF 12093 41.6 mm SL; male. India: Manipur:Ukhrul District, Challou River at Poi.

FIGURE 3. Map showing collection locality of Pethia poiensis (Challou River).

FIGURE2. Osteology of Pethia poiensis, left side illustration, MUMF 12094 & 12101, 36.0¯43.2mm SL: (a) last unbranched dorsal-fin ray; (b) infraorbital series; (c) dorsal view of cranium; (d) pharyngeal teeth; (e) caudal skeleton (Scale bar 1 mm). Abbreviations: CC. compound centrum; F. frontal; Ep. epural; H1–6. hypurals 1–6; IO1–5. infraorbitals 1–5; M. maxilla; Pa. parietal; Ph. parhypural; Pls. pleurostyle; PU2, PU3. preural centra 2, 3.