Garra hexagonarostris, Nebeshwar & Rameshori & Prabina, 2024

Nebeshwar, Kongbrailatpam, Rameshori, Yumnam & Prabina, Salam, 2024, Garra hexagonarostris, a new labeonine fish (Teleostei: Cyprinidae) from the Chindwin basin, Manipur, Northeast India, and a critical review on the taxonomic status of G. minimus, G. alticaputus, G. nigricauda, G. kimini, and G. tyao, Zootaxa 5419 (2), pp. 189-216 : 191-198

Garra hexagonarostris , ( Fig. 1 ) new species

Holotype. MUMF 31001, 133.9 mm SL; India: Manipur: Chandel District: Chakpi River ( Chindwin River basin) at Chakpikarong , 24°12’05” N, 93°54’47” E; Elevation 801m asl; Rameshori et al., 14 December 2011.

Paratypes. MUMF 31002−31012 , 11 , 74.3−111.6 mm SL; − ZSI FF 9992, 2, 88.0 mm SL and 91.6 mm SL; same data as holotype .

Diagnosis. Garra hexagonarostris , a member of ‘proboscis species group’, is distinguished from other members of this group in possessing the following combination of characters: a transverse lobe with 13−35 small- to medium-sized conical tubercles; a prominent, unilobed, hexagon-shaped proboscis with five large-sized conical acanthoid tubercles on anterior margin and three or four medium-sized conical acanthoid tubercles on anteroventral marginal aspect; lateral surface of snout swollen with 8−18 small tubercles; depressed rostral surface of snout flat and creased; 28−29 + 3 = 31−32 lateral-line scales; 8½ branched dorsal-fin rays; 5½ branched anal-fin rays; and labella absent.

Description. Morphometric data of holotype and 13 paratypes are given in Table 1. Body elongate, laterally compressed, more compressed towards caudal peduncle. Dorsal head profile rising gently over snout, slightly convex. Dorsal body profile to dorsal-fin origin slightly convex and dorsal- to caudal-fin origin nearly straight. Ventral profile from pectoral- to pelvic-fin origin straight, and pelvic- to caudal-fin origin slightly convex. Head moderately large, depressed with convex interorbital area; height less than length; width greater than height. Eyes placed dorsolaterally in posterior half of head ( Fig. 1 ).

Snout broadly rounded with transverse lobe covered with 13−35 small- to medium-sized conical acanthoid tubercles, demarcated posteriorly by moderately deep groove; prominent, unilobed, hexagon-shaped proboscis; lateral surface of snout swollen with 8−18 small- to medium-sized conical acanthoid tubercles; and with one or two small-sized conical acanthoid tubercles above nostril, and one to three small-sized conical acanthoid tubercles behind nostril. Proboscis moderately elevated upwards, projected anteriorly up to transverse groove, sharply delineated from depressed rostral surface by narrow deep groove; width smaller than internarial space; anterior margin with five large-sized conical acanthoid tubercles, and anteroventral marginal aspect with three or four medium-sized conical acanthoid tubercles; laterodorsal marginal aspects of posterior half of hexagon and basal side of hexagon lined by six small-sized tubercles ( Fig. 2 ). In some specimens, four or five small-sized tubercles on dorsal surface of proboscis. Depressed rostral surface flat with fine ridges and without tubercles. Sublachrymal groove shallow, not connected to rostral cap groove ( Fig. 3 ).

Barbels in two pairs; rostral barbel shorter than eye diameter; maxillary barbel shorter than rostral barbel. Rostral cap well-developed, highly fimbriate; papillate ventral surface narrow. Upper lip present as a thin band of weakly developed papillae in one row. Upper jaw covered by rostral cap and partly exposed on median marginal region. Gular disc elliptical, shorter than wide and narrower than head width through roots of maxillary barbel, medially positioned, relatively large (disc width 54−65% HL, disc length 36−47% HL). Torus slightly arched medially and highly arched laterally on each side, its lateral extension reaching beyond imaginary vertical line through lateral margin of pulvinus; anterior extension reaching anterior margin of lower jaw; pulvinus relatively large (width 35−43% HL; length 24−32% HL), its anterior and posterior halves equally rounded, width 1.2−1.4 times length; labella absent, one slight incision on outer lateral side of each anterolateral region of labrum; labrum extending posteriorly beyond vertically to posterior margin of eye; toral groove shallow; papillae on papillate ventral surface of rostral cap, labella, and labrum rounded, evenly arranged; papillae on torus elongated and fleshy; papillae on inner half of whole length of labrum larger and coarsely arranged ( Fig. 4 ).

Dorsal fin with 3 (14) simple and 8½ (14) branched rays; last simple ray shorter than head length; distal margin concave; origin closer to snout tip than to caudal-fin base, inserted anterior to vertical through pelvic-fin origin; first branched ray longest, last branched ray not extending vertically to anal-fin origin. Pectoral-fin with 1 (14) simple and 11 (9) or 12* (5) branched rays, reaching beyond midway to pelvic-fin origin when adpressed; length shorter than head length; margin subacuminate; fifth branched ray longest, not extending to base of pelvic fin. Pelvic fin with 1 (14) simple and 8 (14) branched rays, reaching beyond midway to anal-fin origin, slightly surpassing anus; second branched ray longest, not extending to base of anal fin; origin closer to anal-fin origin than to pectoral-fin origin, inserted below base of third branched dorsal-fin ray; distal margin slightly convex.Anal fin short, with 3 (14) simple and 5½ (14) branched rays; first branched ray longest, reaching base of caudal fin; distal posterior margin concave; origin closer to caudal-fin base than to pelvic-fin origin. Anus closer to anal-fin origin than to pelvic-fin origin. Caudal fin forked; tip of lobes moderately pointed; lower lobe slightly longer; tenth ray (counting from upper lobe) shortest.

Lateral line complete, with 28–29 + 3 i.e., 31 (6) or 32* (8) scales. Transverse scale rows above lateral line 4½ (14); scales between lateral line and anal-fin origin 3½ (14); scales between lateral line and pelvic-fin origin 2½* (10) or 3½ (4). Circumpeduncular scale rows 12 (14). Predorsal scales 9* (6) or 10 (8); regularly arranged, same size as flank scales. Chest and belly scaled; scales on chest smaller and under thin skin. Preanal scales 3 (14). Dorsal-fin base scales 5 (7) or 6* (7). Anal-fin base scales 4 (14).

Osteology. Total vertebrae: 32 (1), comprising 21 abdominal + 11 caudal vertebrae; predorsal vertebrae 9 (1).

Coloration. In 10% formalin, head, dorsum and side dark brown or dark gray. Mouth, chest, and abdomen yellowish. Dorsal, pectoral, pelvic and anal fins greyish brown. Distal dorsal marginal region of pectoral fin light brown. Dorsal surface of pelvic fin light brown. Caudal fin greyish. Five or six narrow dark black stripes on caudal peduncle. An arch-shaped black spot on opercle immediately anterior to upper angle of gill opening. Base of last 5 branched dorsal-fin rays faintly spotted.

Distribution and habitat. Presently known only from the Chakpi River at Chakpikarong (Chindwin River basin), Manipur, India ( Fig. 5 ). The new species was collected from a swift-flowing riffle, over a substrate of gravel and bed rock ( Fig. 6 ). Co-occurring species collected from the type locality includes members of the genera Balitora, Channa, Glyptothorax, Mastacembelus , Neolissochilus , Psilorhynchus, Schistura and Tor .

Etymology. The specific epithet is derived from Latin ‘ hexagonum ’, meaning ‘six-sided figure or shape’, and ‘ rostrum (rostris) ’, meaning ‘beak’ or ‘bill’, referring to the hexagon-shaped proboscis. An adjective.

Discussion. The new species, Garra hexagonarostris belongs to the ‘proboscis species group’ of Nebeshwar & Vishwanath (2017) characterized by a unilobed, hexagon-shaped proboscis, with large conical acanthoid tubercles on proboscis and transverse lobe. The new species is compared with 28 valid species of the ‘proboscis species group’ distributed in four river basins (Brahmaputra, Chindwin, Barak, and Kaladan) draining Northeast India and adjoining regions in Bhutan, Tibet ( China), and Bangladesh. These species are: G. gotyla (Gray, 1832) ; G. nasuta ( McClelland, 1838) ; G. kalpangi Nebeshwar, Bagra & Das, 2012 ; G. arunachalensis Nebeshwar & Vishwanath, 2013 ; G. birostris Nebeshwar & Vishwanath, 2013 ; G. quadratirostris Nebeshwar & Vishwanath, 2013 ; G. binduensis Das, Kosygin & Panigrahi, 2016 ; G. bimaculacauda Thoni, Gurung & Mayden, 2016 ; G. parastenorhynchus Thoni, Gurung & Mayden, 2016 ; G. tamangi Gurumayum & Kosygin, 2016 ; G. biloborostris Roni & Vishwanath, 2017 ; G. clavirostris Roni, Sarbojit & Vishwanath, 2017 ; G. motuoensis Gong, Freyhof, Wang, Liu, Liu, Lin, Jiang & Liu, 2018 ; G. yajiangensis Gong, Freyhof, Wang, Liu, Liu, Lin, Jiang & Liu, 2018 ; G. ranganensis Tamang, Sinha, Abujam & Kumar, 2019 ; G. chathensis Ezung, Shangningam & Pankaj, 2020 ; G. jaldhakaensis Kosygin, Shangningam, Singh & Das, 2021 ; and G. langlungensis Ezung, Shangningam & Pankaj, 2021 from the Brahmaputra; G. litanensis Vishwanath, 1993 ; G. cornigera Shangningam & Vishwanath, 2015 ; G. trilobata Shangningam & Vishwanath, 2015 ; G. chindwinensis Premananda, Kosygin & Saidullah, 2017 ; G. moyonkhulleni Moyon & Arunkumar, 2018 ; G. tezuensis Thoidingjam, Ngangbam, Linthoingambi & Singh, 2023 ; and G. chingaiensis Abonmai, Linthoingambi, Ngangbam, Thoidingjam & Singh, 2023 from the Chindwin; G. substrictorostris Roni & Vishwanath, 2018 ; and G. paratrilobata Roni, Chinglemba, Rameshori & Vishwanath, 2019 from the Barak-Meghna; and G. koladynensis Nebeshwar & Vishwanath, 2017 from the Kaladan.

Garra hexagonarostris differs from its congeners in the Chindwin except G. litanensis , G. jaldhakaensis , G. tezuensis , and G. chingaiensis in the possession of unilobed (vs. bilobed or trilobed) proboscis on snout. Garra hexagonarostris differs from G. litanensis in having hexagon-shaped (vs. square-shaped) proboscis with mediumto large-sized conical acanthoid (vs. small-sized) tubercles; fewer transverse scale rows above lateral line (4½ vs. 5½); presence (vs. absence) of scales on chest; longer snout (50−57% HL vs. 47−48), head (24.6−30.4% SL vs. 19.9−23.5), pectoral fin (21.1−26.3% SL vs. 18.5−20.0), and anal fin (18.1−22.0% SL vs. 16.2−17.9). Garra hexagonarostris differs from G. jaldhakaensis in the possession of a hexagon-shaped (vs. quadrate-shaped) proboscis, with 5 large-sized conical acanthoid tubercles on anterior margin (vs. 5−6 uni- to bicuspid tubercles on each side of the anterolateral margin) and 3–4 medium-sized acanthoid (vs. 8–10 uni- to bicuspid) tubercles on anteroventral marginal aspect; fewer lateral-line scales (31−32 vs. 33), branched pectoral-fin rays (11−12 vs. 14), and circumpeduncular scale rows (12 vs. 16); greater number of simple rays of dorsal (iii vs. ii) and anal fins (iii vs. ii); and presence of black spot anterior (vs. posterior) to upper angle of gill opening. Garra hexagonarostris differs from G. tezuensis in having prominent (vs. incipient) proboscis on snout; greater number of branched anal-fin rays (5 ½ vs. 4 ½); more transverse scales rows above lateral line (4 ½ vs. 3 ½); presence (vs. absence) of black stripes on caudal peduncle; and presence of a black spot anteriorly (vs. posteriorly) to upper angle of gill opening. Garra hexagonarostris differs from G. chingaiensis in having hexagon-shaped (vs. quadrate-shaped) proboscis; fewer lateral-line scales (31−32 vs. 34−35), branched pectoral-fin rays (12 vs. 16); and presence of black spot anteriorly (vs. posteriorly) to upper angle of gill opening.

Garra hexagonarostris further differs from congeners in the Chindwin in having fewer lateral-line scales (31−32 vs. 33 in G. cornigera , 34 in G. chindwinensis and G. moyonkhulleni ); sublachrymal groove not connected (vs. connected in G. cornigera and G. moyonkhulleni ) to rostral cap groove; and fewer branched pectoral-fin rays (11−12 vs. 13−14 in G. chindwinensis , 13 in G. cornigera , 14 in G. moyonkhulleni ); from G. chindwinensis in absence (vs. presence) of slightly arched papillated transverse lobe on anterior portion of pulvinus; and forward projection of proboscis reaching up to (vs. beyond) transverse groove on snout; from G. cornigera in having unilobed (vs. bilobed) proboscis; and greater number of tubercles on transverse lobe of snout (13−35 vs. 8−13); from G. trilobata in having unilobed (vs. trilobed) proboscis; conical (vs. multicuspid) tubercles on proboscis and transverse lobe of snout; and presence of black spot anteriorly (vs. posteriorly) to upper angle of gill opening; from G. moyonkhulleni in having greater number of branched dorsal-fin rays (8 vs. 7), pelvic-fin rays (8 vs. 7), and predorsal scales (9−10 vs. 8); fewer dorsal-fin base scales (5−6 vs. 7−8); and greater number of tubercles on transverse lobe of snout (13−35 vs. 9−12).

Garra hexagonarostris differs from congeners in the Brahmaputra except G. arunachalensis , G. bimaculacauda , G. binduensis , G. clavirostris , G. kalpangi , G. langlungensis , G. parastenorhynchus , and G. quadratirostris in the possession of unilobed (vs. bilobed or trilobed) proboscis. Garra hexagonarostris differs from all of the above congeners in the possession of a hexagon-shaped proboscis (vs. quadrate-shaped in G. arunachalensis , G. bimaculacauda , G. quadratirostris , and G. kalpangi ; club-shaped in G. parastenorhynchus and G. clavirostris ; anteriorly round-shaped in G. binduensis and G. langlungensis ); fewer lateral-line scales (31−32 vs. 35 in G. arunachalensis , 35−37 in G. kalpangi and G. binduensis , 37 in G. quadratirostris , 33−34 in G. clavirostris , 32−34 in G. bimaculacauda ); sublachrymal groove not connected (vs. connected in G. quadratirostris , and G. clavirostris ) to rostral cap groove; and presence of black spot anteriorly (vs. posteriorly in G. clavirostris and G. langlungensis ) to upper angle of gill opening.

Garra hexagonarostris further differs from G. arunachalensis in having greater number of tubercles on anterior margin of proboscis (5 vs. 3); and presence (vs. absence) of black spot anteriorly to upper angle of gill opening; from G. bimaculacauda in absence (vs. presence) of two distinct black spots on caudal fin, one on tip of upper lobe and the other on tip of lower lobe; 5 large-sized (vs. 3 small-sized) conical tubercles on anterior margin of proboscis; and fewer transverse scale rows above lateral line (4 vs. 6); from G. parastenorhynchus in possession of conical (vs. multicuspid) tubercles on transverse lobe; greater number of branched pelvic-fin rays (8 vs. 7); larger gular disc (disc width 54−65% HL vs. 46−52; pulvinus length 24−32% HL vs. 16−21; pulvinus width 35−43% HL vs. 24−27); and lacking (vs. possession of) labella; from G. kalpangi in having prominent (vs. weakly developed) proboscis; fewer circumpeduncular scale rows (12 or 14 vs. 16); and presence (vs. absence) of lateral stripes on side of body; from G. binduensis in having longer dorsal-fin base (17.6−21.5% SL vs. 15.7–17.9); from G. quadratirostris in greater number of tubercles on anterior margin of proboscis (5 large-sized tubercles vs. 3 or 4 small- to medium-sized tubercles); from G. clavirostris in proboscis with 5 large-sized conical (vs. 5–9 medium- to large-sized uni- to multicuspid) tubercles on anterior margin, and with 3–4 conical (vs. 5–6 uni- to multicuspid) tubercles on anteroventral marginal aspect; from G. langlungensis in having prominent (vs. incipient) proboscis; fewer circumpeduncular scale rows (12 vs. 13−15); and greater number of conical acanthoid tubercles on transverse lobe of snout (13−35 small- to medium-sized vs. 8–12 small-sized).

Garra hexagonarostris further differs from the congeners of the Brahmaputra in the possession of a hexagon-shaped proboscis (vs. two separate and slightly elevated arch-shaped lobes in G. biloborostris ; quadrate-shaped in G. birostris , G. gotyla , G. motuoensis , and G. yajiangensis ; triangular shaped in G. tamangi ); having fewer lateral-line scales (28–29 + 3 =31–32 vs. 30 + 3 = 33 in G. biloborostris ; 33–34 in G. birostris , G. gotyla , and G. tamangi ; 34–35 + 2= 36–37 in G. motuoensis and G. ranganensis ; 34–36 in G. yajiangensis ), circumpeduncular scale rows (12 vs. 16 in G. biloborostris , G. birostris , G. chathensis , and G. gotyla ), and branched pectoral-fin rays (11–12 vs. 13–14 in G. chathensis , G. motuoensis , G. tamangi , and G. yajiangensis ; 13–15 in G. ranganensis ); sublachrymal groove not connected (vs. connected in G. biloborostris , G. chathensis , and G. ranganensis ) to rostral cap groove; presence of black spot anteriorly (vs. posteriorly in G. birostris , G. chathensis , and G. gotyla ) to upper angle of gill opening; and posteriormost margin of pulvinus extending beyond (vs. extending upto, in G. biloborostris and G. gotyla ) imaginary vertical line through posterior margin of eye; from G. biloborostris in having transverse groove demarcating transverse lobe, not extending laterally on each side (vs. extending laterally on each side to make the transverse lobe, a prominent knob-like protuberance); and fewer anal-fin base scales (3–4 vs. 5–6).

Garra hexagonarostris further differs from G. birostris in the possession of a black spot anteriorly (vs. posteriorly) to upper angle of gill opening; from G. chathensis in having greater number of tubercles on transverse lobe (13–35 vs. 10–12); and conical (vs. bicuspid) tubercles on proboscis; from G. gotyla in having greater number of tubercles on transverse lobe (13–35 vs. 9–13); and fewer transverse scale rows between lateral line and anal-fin origin (3½ vs. 4½); from G. motuoensis in having longer snout (50–57% HL vs. 42–49), and head (24.6–30.4% SL vs. 21.2–23.8); shorter caudal peduncle (10.1–15.4% SL vs. 16.8–20.3); and greater prepectoral (22.6–25.5% SL vs. 18.7–20.2), and preanal distance (76.9–84.9% SL vs. 72.7–75.4); from G. ranganensis in having deeper caudal peduncle (12.4–14.5% SL vs. 11.6–12.0); from G. tamangi in presence of conical (vs. uni-to tetracuspid) tubercles on transverse lobe of snout; from G. yajiangensis in absence (vs. presence) of grey submarginal band on distal half of dorsal fin; more anteriorly-situated anus (distance from anus to anal fin 29−40% of pelvic-anal distance vs. 19−24); and smaller gular disc (disc length 36–47% HL vs. 49–58, disc width 54–65% HL vs. 66–77, pulvinus length 24–32% HL vs. 33–40, pulvinus width 36–43% HL vs. 44–50); from G. nasuta sensu M’Clelland in absence (vs. presence) of distinct pit between nares.

Garra hexagonarostris differs from congeners, viz., G. substrictorostris , G. paratrilobata , and G. koladynensis of the Barak-Meghna and Kaladan River basins in the possession of conical (vs. multicuspid) acanthoid tubercles on transverse lobe and proboscis of snout; hexagon-shaped proboscis (vs. quadrate-shaped in G. substrictorostris , anteriorly round-shaped in G. paratrilobata and G. koladynensis ); and fewer circumpeduncular scale rows (12 vs. 16), lateral-line scales (31−32 vs. 33−34), and branched pectoral-fin rays (11−12 vs. 14−15). Garra hexagonarostris further differs from the above three congeners in the possession of unilobed (vs. trilobed in G. paratrilobata and G. koladynensis ) proboscis; and presence of black spot anteriorly (vs. posteriorly in G. substrictorostris and G. paratrilobata ) to upper angle of gill opening; from G. substrictorostris in possession of hexagon-shaped (vs. quadrate-shaped) proboscis; sublachrymal groove not connected (vs. connected) to rostral cap groove; and fewer transverse scale rows above lateral line (4½ vs. 5½); from G. paratrilobata in possession of flat (vs. concave) depressed rostral surface; and fewer branched pelvic-fin rays (8 vs. 9), and circumpeduncular scale rows (12 vs. 16).

Status of Garra alticaputus , G. kimini , G. minimus , G. nigricauda , and G. tyao . Arunachalam et al. 2013, Journal of Fisheries and Aquaculture, 4: 121–138, described Garra alticaputus , G. kimini , G. minimus , and G. nigricauda from the upper Brahmaputra River basin in Arunachal Pradesh, and subsequently Arunachalam et al. 2014, Species, 10: 58–78 described G. tyao from the Tyao River, Kaladan River basin in Mizoram. Nebeshwar & Vishwanath (2017: 48) indicated uncertainties regarding the identity of these species, and stated that “[t]he characters, mainly on the colour and meristic data, of G. nigricauda are similar to those of G. arunachalensis ; G. minimus to those of G. quadratirostris ; G. kimini and G. alticaputus to those of G. birostris ; G. tyao to those of G. rakhinca ;”.

While describing these four species, Aruanchalam et al. 2013, Journal of Fisheries and Aquaculture, 4: 121– 138 presented many ambiguous characters as well as misused several terminologies related to oral and gular disc structures (see Table 2). A critical review and comparison of characters of G. nigricauda with G. arunachalensis ( Table 3); G. minimus with G. quadratirostris ( Table 4); and G. alticaputus and G. kimini with G. birostris ( Table 5) reveal several inconsistencies and inaccuracies which lead us to consider G. minimus as a junior synonym of G. quadratirostris ; G. nigricauda , as a junior synonym of G. arunachalensis ; and G. alticaputus and G. kimini , as junior synonyms of G. birostris .

While Solo & Lalnuntluanga (2018) studied the species diversity of Garra in the Kaladan River and its tributaries in Mizoram, they considered G. tyao as a junior synonym of G. rakhinica . The characters distinguishing G. tyao with G. rakhinica mentioned in Arunachalam et al. 2014, Species, 10: 58–78 are critically reviewed ( Table 6), revealing that G. tyao is indeed a junior synonym of G. rakhinica .

In addition to the issues presented in Tables 2, 3, 4, 5, and 6, the text in Arunachalam et al. 2013, Journal of Fisheries and Aquaculture, 4: 121–138, is full of glaring errors and inaccuracies ( Table 7 ), suggesting that the manuscript may not have even undergone a proper peer-review. Similar issues with papers of the same author/s have been highlighted previously by Conway (2018) and Raghavan et al. (2014), and results in the destabilization of taxonomic efforts in a global biodiversity hotspot.

Figures

FIGURE 1. Garra hexagonarostris, sp. nov., holotype, MUMF 31001, 133.9 mm SL; a. lateral, b. dorsal, and c. ventral views. India: Manipur, Chakpi River.

FIGURE 2. Garra hexagonarostris, holotype, morphology of snout showing transverse lobe, proboscis, and lateral surface.

FIGURE 3. Garra hexagonarostris, holotype, showing sublachrymal groove and rostral cap groove.

FIGURE 4. Garra hexagonarostris, holotype, showing gular disc and oral structures.

FIGURE 5. Map showing the type locality of Garra hexagonarostris in Chakpi River, Manipur, India.

FIGURE 6. Chakpi River, Manipur, India; habitat of Garra hexagonarostris.