Pethia sahit

Katwate, Unmesh, Kumkar, Pradeep, Raghavan, Rajeev & Dahanukar, Neelesh, 2018, A new syntopic species of small barb from the Western Ghats of India (Teleostei: Cyprinidae), Zootaxa 4434 (3), pp. 529-546: 531-541

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Pethia sahit

sp. nov.

Pethia sahit  , sp. nov.

( Fig. 2 View Figure )

Holotype. BNHSAbout BNHS FWF 532, 30.6 mm SL, male; India: Maharashtra: Kolhapur District: Ajara Taluk: Hiranyakeshi River near Ghatkarwadi , 16.054°N and 74.066°E, 675m a.s.l., U. Katwate, N. Dahanukar, P. Kumkar and N. Sawant, 0 3 May 2014.GoogleMaps 

Paratypes. BNHSAbout BNHS FWF 533–535 and 540–541, 5 ex., 21.5–30.6 mm SL, same data as holotypeGoogleMaps  ; BNHSAbout BNHS FWF 536–539, 4 ex., 28.5–30.3 mm SL, same locality as holotype, U. Katwate, N. Dahanukar, R. Britz, P. Kumkar, N. Sawant, 0 7 February 2016GoogleMaps  ; WILD-17-PIS-349, 27.7 mm SL, same data as BNHSAbout BNHS FWF 536–539GoogleMaps  ; BNHSAbout BNHS FWF 606, 27.9 mm SL, same data as BNHSAbout BNHS FWF 536–539.; WILD-14-PIS-075 and BNHSAbout BNHS FWF 100, 30.0–32.0 mm SL, India: Maharashtra: Kolhapur District: Hiranyakeshi River near Gavse-Ajara , 16.068°N, 74.091°E, 690 m a.s.l., U. Katwate, M. Paingankar and N. Dahanukar, 11th June 2013 (both specimens listed as paratypes of P. longicauda  by Katwate et al. 2014c).GoogleMaps 

Diagnosis. Pethia sahit  is distinguished from all known species of Pethia  by a combination of characters that includes a small-sized body (21.5–32.0 mm in SL); absence of barbels; thin lips; an incomplete lateral line with 3– 6 pored scales; 19–22 scales in lateral series; 8–9 pre-dorsal scales; 9–10 pre-pelvic scales; 12–17 pre-anal scales; 4½ scales between dorsal-fin origin and lateral-line row; 2½ scales between lateral line row and pelvic-fin origin; scale row adjacent to the dorsal side of lateral-line scale row usually intercalated above and after the 6th scale of the lateral-line scale row; last unbranched dorsal-fin ray strong, serrated, with 8–13 serrae on its unsegmented distal half, 2–4 serrae on its segmented apical half; dorsal fin originating behind the pelvic-fin origin; four free supraneurals; five pre-dorsal neural spines; 4–5 gill rakers on lateral and 8–9 on median margin of first ceratobranchial, and three on lateral and five on median margin of first epibranchial; 4+4 pre-dorsal vertebrae; 4+25 total vertebrae, with 4+13 abdominal and 12 caudal vertebrae; dorsal, pectoral, pelvic, anal and caudal fins without any bands or spots, deep yellow-orange in color or deep red with a pale tint of orange in mature males; a dark-black vertically elongate humeral spot, overlapping the 4th lateral-line scale, extending over the base of one scale above and below the 4th scale; caudal peduncle spot dark, covering 14th–16th scales in lateral-line scale row.

Description. A small, deep-bodied Pethia  , attaining a size of 30.6 mm SL in males and 32.0 mm SL in females. For general shape and appearance see Figure 2 View Figure . Morphometric and meristic data for the holotype and 13 paratypes are provided in Table 1.

Body short, deep, its length 2.6–2.8 times its depth; compressed laterally; dorsal body profile convex, rising gradually up to dorsal-fin origin, thereafter sloping downwards gradually to hypural notch. Ventral profile moderately convex up to base of pelvic fin, running almost straight towards anal-fin origin, sloping down sharply from anal-fin origin towards posterior end of anal-fin base, then almost straight to hypural notch. Caudal peduncle broad, short, its length 1.2–1.8 times its depth. Head small, stout, laterally compressed, its length 1.2–1.3 times its depth. Snout blunt, short, lateral fold present, devoid of tubercles, its length shorter than the eye diameter. Eyes large, mid-laterally positioned, closer to snout tip than posterior margin of operculum, diameter 0.7–0.9 times interorbital width. Mouth small, subterminal, ventrally U-shaped, angle of gape not reaching vertical from anterior margin of eye. Lips thin, not interrupted, upper lip relatively fleshier than lower lip. Barbels absent.

Dorsal fin originating posterior to pelvic-fin origin, closer to tip of snout than to base of caudal peduncle, reaches the anterior margin of caudal spot, tip rounded, its distal margin straight, dorsal fin length 0.7–1.1 times of head length. Dorsal fin with four unbranched (consisting of three supernumerary rays and one unbranched seriallyassociated ray) and eight branched serially-associated rays; the single unbranched serially-associated ray strong, its proximal half smooth, serrated posteriorly with 8 (3), 9 (4), 10 (3), 11 (1), 12 (2) or 13 (1) serrae on unsegmented distal half, 2 (7), 3 (6) or 4 (1) serrae on segmented apex. Pectoral fin with one unbranched and 10 (1), 11 (7) or 12 (6) branched rays, its tip rounded, reaching one (3) or half scale (5) anterior to or overlapping (6) pelvic-fin origin. Pelvic fin with one unbranched and seven branched rays, its tip rounded, nearly reaching the vent when adpressed. Anal fin with four unbranched (consisting of three supernumerary rays and one unbranched serially-associated ray) and five branched serially-associated rays, its distal margin straight, with rounded corners. Caudal fin forked, lobes representing less than half of total fin length, tips rounded. Principal caudal-fin rays dorsally 8 (9) or 9 (3), ventrally 8; procurrent rays dorsally 8, ventrally 6 (2) or 7 (12).

Lateral line incomplete, piercing anteriormost 3 (3), 4 (1), 5 (9) or 6 (1) scales; 19 (2), 20 (6), 21 (4) or 22 (2) scales in lateral series, which runs straight up to 4th or 5th scale, gradually sloping down and rising crescentically at anterior margin of caudal spot, then running straight up to caudal-fin base. Scale row adjacent to dorsal side of lateral line or mid-lateral scale row usually intercalated ( Fig. 4c View Figure ), originating above and after the 6th scale of lateralline scale row (13) or in some cases complete (1). Scales in transverse row 4½/1/2½, pre-dorsal scales 8 (11) or 9 (3), pre-pelvic scales 9 (2) or 10 (12), pre-anal scales 12 (1), 13 (2), 14 (6), 15 (1) or 17 (4), circumpeduncular scales 12. Pelvic axillary scale present, reaching to one-fourth of adpressed pelvic-fin length.

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Osteology. Based on BNHSAbout BNHS FWF 535, 30.6 mm SL, cleared and double stained, see Figure 3a View Figure . Infraorbital 2 broad, maximum width greater than three-fourths infraorbital 4; Infraorbital 3 largest among infraorbital series, deep, medially broad, less wide on anterior and posterior ends; infraorbital 4 ovoid, less wide than infraorbitals 1 and 3; infraorbital 5 small, with well-developed anterior and posterior laminae. Gill rakers simple, 4–5 on lateral, 8–9 on median margin of first ceratobranchial; 3 on lateral, 5 on median margin of first epibranchial. Four free supraneurals; pre-dorsal neural spines 5. Dorsal fin comprised of twelve rays (iii-i-8), three supernumerary unbranched, one serrated unbranched serially associated, eight branched serially-associated rays; articulated with a series of pterygiophores, one proximal-middle radial, eight proximal radials placed between neural spines V8 /V9– V 14/V15, eight distal radials, five middle radials. Anal fin comprised of nine rays (iii-i-5), three supernumerary unbranched, one smooth unbranched serially associated and five branched serially-associated rays; articulated with a series of pterygiophores, one proximal-middle radial, five proximal radials placed between neural spines V17 / V18–V 19/V20, five distal radials and three middle radials. Caudal-fin rays supported by neural and hemal spines of second and third preural centra, an epural element, pleurostyle, six hypurals and the parhypural; single epural running laterally with anterior margin of pleurostyle on dorsal half. Weberian apparatus constitutes first four vertebrae. 4+4 pre-dorsal vertebrae; 4+25 total vertebrae, with 4+13 abdominal and 12 caudal vertebrae.

Coloration in preservative. Body above lateral-line scale row grayish brown; snout, head, dorsum dark brown; lower lip, cheek, gill cover, and region of exposed cleithrum pale yellowish white with sparse dark-brown pigments; lower head, chest and abdominal region uniformly pale yellowish-white ( Fig. 2b View Figure ). Iris whitish, a dark strip of pigments above and below the pupil running vertically across iris. Body with one dark-black verticallyelongate humeral spot, overlapping the 4th lateral-line scale, extending and tapering towards base of one scale above and below the 4th scale of lateral-line row. Caudal-peduncle spot dark brownish-black, noticeably small, round, almost ¾ of eye diameter, not encircling caudal peduncle, anterior margin of caudal spot overlapping vertically with posterior most end of dorsal fin and overlapping medially with vertical plane from posterior end of anal fin base, covers the 14th–15th (6), 15th (4), 15th–16th (1) and 16th (3) scales of lateral series. Fins hyaline, without any markings, bands or spots. Scale pockets with dark dense pigmentation, posterior periphery lighter pale-brown, scales below the lateral-line row lighter brown with conspicuous darker margin. In mature males pigmentation in scales pockets becomes dark and appears to be in crescentic shape.

Coloration in life. Body bright yellowish with iridescence on scales, scale pockets deeply pigmented with melanophores ( Fig. 2a View Figure ). Dorsum relatively more densely pigmented with melanophores than ventral half of body; lower head, chest, and abdomen silvery. Position of humeral and caudal spots as described for preserved specimens. Dorsal, pectoral, pelvic, anal and caudal fins without any bands or spots, deep yellow-orange or sometimes appearing deep red with pale tint of orange in mature males ( Fig. 4a View Figure ). Iris uniform iridescent silver, outer and inner border marked with thin fringe of yellow; dark vertical bar passing though eye. Opercle and region of infraorbital series sparsely studded with melanophores.

Etymology. The species epithet ‘ sahit  ’ (Sanskrit) means together, and refers to the syntopy of the new species with P. longicauda  . A noun in apposition.

Common name. Prakash’s Barb (after Prakash Tambe, a local resident, who helped us in the field surveys leading to the discovery of the new species).

Distribution. Pethia sahit  is currently known only from two localities, viz., Ghatkarwadi and Gavse-Ajara, located in the upstream catchments of the east-flowing Hiranyakeshi (a tributary of the Krishna River) in Ajara, Kolhapur District, Maharashtra, India ( Fig. 1 View Figure ).

Habitat and ecology. Pethia sahit  occurs in side pools as well as in parts of the main river channel with a sluggish water current and with fallen branches and other detritus, and with sand, small boulders and gravel as substratum ( Fig. 5a View Figure ; supplementary movie of underwater observation is available from m9.figshare.6138965. v1). Co-occurring fishes in the type locality of P. sahit  included Pethia longicauda  , Oreichthys duospilus  , Puntius amphibius  , Rasbora dandia  , Devario malabaricus  , Balitora laticauda  , Lepidocephalichthys thermalis  , Paracanthocobitis  sp., Osteochilichthys thomassi  and juveniles of Tor khudree  .

In-situ underwater observations at Ghatkarwadi revealed that P. sahit  occurs syntopically with large shoals of P. longicauda  (see Fig. 5b View Figure ; supplementary movie of underwater observation is available from 10.6084/m9.figshare.6138965. v1). The syntopic occurrence of the two species was observed at both localities, i.e. Ghatkarwadi (type locality of P. sahit  ) and Gavse-Ajara (type locality of P. longicauda  ). While collecting specimens with drag nets, P. longicauda  was always numerically dominant, and the ratio of specimens of P. sahit  to P. longicauda  was 3:26, 4:32, 2:17 and 9:29, in four different sampling sweeps.

Phylogenetic analysis. The maximum-likelihood tree for the mitochondrial cytb gene sequence was estimated using the best nucleotide substitution model (TPM3+R4, BIC = 26499.085, lnL=-12530.518, df = 204). Phylogenetically, P. sahit  and P. longicauda  are not sister taxa ( Fig. 6 View Figure ): they show a genetic distance of 13.6–14.3% ( Table 2). Further, P. sahit  appears to have no closely-related congener from the Western Ghats region ( Fig. 6 View Figure ). Its genetic distance from all its Indian congeners is greater than 12.0% ( Table 2), more than 11.8% from its Sri Lankan congeners, and 16.1–16.4% from P. padamya  of Myanmar. Pethia sahit  clades with P. phutunio  , another smallsized Pethia  ; however, the genetic distance between the two is 13.5–14.0% ( Table 2).

As part of this study, we also found that two paratypes of P. longicauda  (WILD-14-PIS-075 and BNHS FWF 100) which were used for genetic analysis by Katwate et al. (2014c) were in fact individuals of P. sahit  .

Comparisons. Pethia sahit  differs from its Western Ghats congeners P. lutea  , P. punctata  , P. setnai  and P. striata  in having an incomplete (vs. complete) lateral line. It differs from its remaining Western Ghats congeners, P. longicauda  , P. nigripinna  , P. pookodensis  and P. sanjaymoluri  , based on the characteristics listed in Table 3.

Pethia sahit  differs from its syntopic congener P. longicauda  in a number of characters ( Table 3); however, the most prominent difference between the two species is the presence in P. sahit  of an intercalated scale row (vs. absent in P. longicauda  ). In P. sahit  , the scale row adjacent to the dorsal side of lateral line, or mid-lateral scale row, is usually intercalated ( Fig. 4c View Figure ) and originates above and after the 6th scale of lateral-line scale row, while this scale row is absent in P. longicauda  . Apart from this, the male and female coloration in breeding individuals of the two species are different ( Fig. 4 View Figure ). In P. sahit  the dorsal, pelvic, anal and caudal fins are dark yellowish-orange in mature males, vs. hyaline in P. longicauda  . Furthermore, the mature males and females of P. sahit  are bright yellowish in color, while the general body color of P. longicauda  remains dull pale brown with iridescence on the scales. Further, the two species are genetically divergent by distance of 13.6–14.3% ( Table 2), which is comparatively larger than genetic distance between morphologically distinct species such as P. ticto  vs. P. longicauda  (1.5–2.2%) and P. reval  vs. P. cumingii  (1.9–2.6%).

Pethia sahit  clades with P. phutunio  , a species described from the ponds of north-eastern Bengal, in phylogenetic analysis ( Fig. 3 View Figure ); however, P. sahit  can be clearly distinguished from P. phutunio  by the lower number of transverse scales between the lateral-line series and pelvic-fin origin (2½ vs. 3½); distinct coloration consisting of a humeral and caudal spot (vs. five broad bands on the side of the body); caudal spot not encircling the caudal peduncle (vs. encircling); weakly serrated last unbranched dorsal-fin ray (8¯13 serrae in distal half of serrated ray vs. 17¯19 serrae) and a genetic distance of 13.5–14.0% in mitochondrial cytb gene sequence ( Table 2). Furthermore, both species are geographically isolated from each other by a distance of more than 1500 km: P. phutunio  occurs in the River Ganges and its tributaries in north-eastern India, whereas P. sahit  is restricted to the headwaters of the Hiranyakeshi, a tributary of the east-flowing Krishna River system in the Western Ghats of peninsular India.

Pethia sahit  can be distinguished from the other species of Pethia  occurring in northern and north-eastern India and Myanmar in having an incomplete lateral line (vs. complete in P. expletiforis  , P. guganio  , P. rutila  , P. stoliczkana  and P. tiantian  ), 19–22 scales in mid-lateral scale row (vs. 23–26 in P. ticto  , 24–26 in P. conchonius  25– 29 in P. atra  , 25–26+ 1 in P. aurea  , 21–22+ 1 in P. gelius  , 28–30 in P. khugae  , 22–24 in P. manipurensis  , 21–23 in P. meingangbii  , and 23–24 in P. ornatus  ), two spots over body comprising of a small humeral spot covers the 4th lateral line scale and a caudal spot covering 14th–16th scale of lateral line series scale row (vs. distinct four bands on body and a dark spot at the origin of the dorsal, ventral and anal fins in P. canius  ) and 2½ scales in between lateral line scale row and the pelvic-fin origin (vs. 3½ in P. didi  , P. erythromycter  , P. padamya  , P. poiensis  and P. thelys  , 3½– 4 in P. ticto  , 4½–5½ in P. conchonius  and 4½ in P. nankyweensis  ), and 3–6 lateral-line pored scales (vs. 6–12 in P. ticto  , 6–15 in P. conchonius  , up to 11 pored scales in P. shalynius  , 7–9 in P. poiensis  and 8–9 in P. yuensis  )

Pethia sahit  differs from its Sri Lankan congeners in having an incomplete lateral line (vs. complete in P. nigrofasciata  ), a small humeral spot covering only the 4th lateral series scale (vs. a large vertically-elongated humeral band in P. bandula  , P. cumingii  and P. reval  and three black bars with the addition of a vertical bar beneath the dorsal-fin base in P. nigrofasciata  ), ½4/1/2½ transverse scale rows (vs. ½4/1/4½ in P. bandula  , ½2/1/2½ in P. melanomaculata  and ½3/1/3½ in P. cumingii  and P. reval  ).

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