Gymnostomus Heckel, 1843

Ciccotto, Patrick J. & Page, Lawrence M., 2020, Revision of the Genus Henicorhynchus, with a Revised Diagnosis of Gymnostomus (Cyprinidae: Labeoninae), Copeia 108 (3), pp. 485-502 : 485-502

Gymnostomus Heckel, 1843

Gymnostomus Heckel, 1843:1030 . Type species: Cyprinus ariza Hamilton, 1807:344 , by subsequent designation by Bleeker, 1863:197.

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Mrigala Bleeker, 1859:259 . Type species: Cirrhina bengalensis Bleeker, 1853:136 , by monotypy; also in Bleeker, 1860:427.

Cirrhinichthys Bleeker, 1863:202 . Type species, Cirrhina dussumieri Valenciennes , in Cuvier and Valenciennes, 1842:291, by original description.

Diagnosis.— Member of the cyprinid subfamily Labeoninae based on the ventrally expanded rostral fold, the presence of a superficial posterior labial fold, and the presence of a vomero-palatine organ ( Stiassny and Getahun, 2007). A molecular phylogeny also places Gymnostomus within Labeoninae ( Yang et al., 2012). Gymnostomus is distinguished from other labeonin genera by the following characters: 1) mouth subterminal; 2) upper lip adnate to exposed surface of upper jaw and continuous with lower lip around corner of mouth, not covering entire upper jaw; 3) lower lip attached to lower jaw; 4) rostral barbels present; 5) edge of rostral cap with weakly developed papillous fimbriae forming distinct fringed edge; 6) 8–9 branched dorsal-fin rays; 7) humeral region immaculate, without distinct blotch.

Comparisons.— Gymnostomus is morphologically most similar to Henicorhynchus (see above), Crossocheilus , Epalzeorhynchos , Garra Hamilton, 1822 , Tariqilabeo Mirza and Saboohi, 1990 , and several species currently placed in Cirrhinus . Gymnostomus is distinguished from Henicorhynchus and Cirrhinus by the presence of a rostral cap with weakly projecting fimbriae at edge ( Fig. 10 ; vs. straight edge in C. cirrhosus , C. jullieni , C. microlepis , C. molitorella , C. prosemion , ‘ C.’ inornatus , and ‘ C.’ rubirostris , and either straight edge or edge with a single medial indent in Henicorhynchus ). Gymnostomus possesses rostral barbels (vs. rostral barbels absent in Henicorhynchus and C. microlepis ). The upper lip is adnate to the upper jaw in Gymnostomus (vs. completely surrounding the upper jaw in C. cirrhosus , C. microlepis , ‘ C.’ inornatus , and ‘ C.’ rubirostris ). Species of Crossocheilus , Epalzeorhynchos , Garra , and Tariqilabeo possess more strongly projecting and deeply grooved fimbriae on the rostral cap compared to Gymnostomus ( Ciccotto and Page, 2016b; Ciccotto et al., 2017).

Remarks.— Gymnostomus is composed of three species: G. ariza ; G. fulungee Sykes, 1839 ; and G. horai Bănărescu, 1986 . Gymnostomus horai is distinguished from G. ariza and G. fulungee by the presence of 9 (vs. 8) dorsal-fin rays and 16–18 (vs. 20–22) circumpeduncular scales. Roberts (1997) reported

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Copeia 108, No. 3, 2020

8–9 branched dorsal-fin rays in G. ariza ; however, one of the lots examined in that study (CAS 62067) contained two specimens of Bangana (tentatively identified as B. devdevi [Hora, 1936]) and one specimen of Cirrhinus cirrhosus , all of which possess more than 8 branched dorsal-fin rays. All other specimens examined, as well as the figure from the original description of G. ariza , possess 8 branched dorsal-fin rays. In his revision of Cirrhinus , which included all three species of Gymnostomus listed here, Roberts (1997) diagnosed G. fulungee from other species based on (among other characters) 42–52 scales in the lateral series. Specimens of G. fulungee re-examined here, all from the Deccan plateau of southern India, have 39–52 þ 2–3 lateral-line scales. Most specimens of G. ariza re-examined here, from Bangladesh, India, Nepal, and Pakistan, possess 33–35 þ 2–3 lateral-line scales. However, specimens identified by Roberts (1997) as G. ariza from the Kaveri River basin (CAS 62032) and Pune (CAS SU 34565) in the Deccan plateau possess 36–38 þ 2–3 lateral-line scales. Based on this information, G. fulungee may be separated from G. ariza by having more lateral-line scales (39–52 þ 2–3 vs. 33–38 þ 2–3); however, other scale counts of G. ariza and G. fulungee exhibit some overlap, and we observed no other diagnostic characters separating these species. Additional molecular and morphological data are warranted to better diagnose G. ariza and G. fulungee , with their identities further hampered by the lack of types for both species.

Material examined.— Gymnostomus ariza : Bangladesh: Karnapouli basin: CAS 94081 , 1 (of 4), 120.8 mm SL , Chittagong Hill Tracts, small stream about 30 km north of Khagrachari town , heavily vegetated banks, 23.36638N, 91.91248E, 6 June 1996 . India: Bhima basin(?): CAS SU 34565 , 1 , Poona , April 1937 . Brahmaputra basin: CAS SU 41128 , 1 , Assam, Tezpur fish market, 26.62988N, 92.79718E. Ganges basin: CAS SU 34566 , 1 , Ganges River delta at Pulta , 22.78728N, 88.34458E, 10 April 1937 ; USNM 165085 , 1 , Bihar, Chotanagpur. Hooghly basin(?): CAS SU 34564 , 3 , West Bengal, Calcutta , 22.58788N, 88.34848E, April 1937 . Kaveri basin: CAS 62032 , 9 , Karnataka, NW/ WNW of Mysore, 12.39798N, 76.78198E, 5–8 January 1985 . Mahanadi basin: CAS 79176 , 1 , Orissa, Hirakud Reservoir and Sambalpur market, 21.46898N, 83.96348E, 22–24 February 1985 ; CAS SU 34568 , 2 , Mahanadi, Siliguri , 26.71288N, 88.41168E, April 1937 . Nepal: Ganges basin: CAS 50369 , 1 , Terai, market at Kalaiya (Khailaya), 12 km east of Birganj , 1 May 1975 ; CAS SU 52929 , 6 , Biratnagar and vicinity—purchased at bazaar, 26.46178N, 87.288E, 27– 30 November 1955 . Pakistan: Indus basin: CAS 24237 , 5 , Sindh, Indus River, 523 km north of Karachi (i.e., 8 km north of Sukkur ), 27.76758N, 68.8588E, 1–11 November 1968 . Unknown basin: CAS 29653 , 1 , Arabian Sea, off Karachi , 24.80488N, 66.97448E, 22 October 1973 . Gymnostomus fulungee : India: Bhima basin(?): CAS SU 41123 , 5 , Maharashtra, Poona , Bombay Pres. , 10.49538N, 99.25528E, 3 April 1937 . Gangavali basin: CAS 61967 , 2 , Karnataka, North Kanara, Bedti (Gangavali) R., ca. 15 km east of Yellapur , 14.96798N, 74.86668E, 25 January 1985 . Penna basin(?): CAS SU 34563 , 2 , Andhra Pradesh, Kodur, Cuddapah , 14.47178N, 78.82098E, April 1937 . Unknown basin: CAS SU 41124 , 2 , Mugao Dharwar , Bombay Pres. , 15.44188N, 74.91688E, 21 July 1937 . Gymnostomus horai : Myanmar: Inle Lake : CAS 81548 , 24 , 20.54748N, 96.91618E, February 1994 ; USNM

Ciccotto and Page—Revision of Henicorhynchus

191451, 1, holotype, Shan State, 20.54748N, 96.91618E, 31 January 1956 .

‘Cirrhinus’ inornatus and ‘Cirrhinus’ rubirostris

Remarks.— The type specimens of ‘ Cirrhinus ’ inornatus , recognized as Gymnostomus inornatus in Kottelat (2013), and ‘ C.’ rubirostris both possess a subterminal mouth, an upper lip that covers the entire upper jaw, a post-oral groove separating the lower lip from the lower jaw, a smooth edge to the rostral cap, maxillary barbels, 9 branched dorsal-fin rays (see below), 34–35 lateral-line scales, and a supracleithral blotch. This combination of characters is not observed in any species of Gymnostomus or Henicorhynchus , or other putative species of Cirrhinus ( C. cirrhosus , C. jullieni , C. microlepis , C. molitorella , and C. prosemion ). However, this combination of characters is observed in specimens of Labeo boga ( Hamilton, 1822) examined here. Although no types are known for L. boga , the figure in the original description by Hamilton (1822) depicts a specimen with an inferior mouth, a post-oral groove, a smooth rostral cap, maxillary barbels, 9 branched dorsal-fin rays, and a supracleithral blotch. Based on morphological similarities with L. boga , particularly in regard to oromandibular structures ( Fig. 11 ), C. inornatus and C. rubirostris are assigned to the genus Labeo .

In the original diagnosis of L. inornatus, Roberts (1997) noted ‘‘branched dorsal fin rays usually 9.’’ Two specimens of CAS 91776 included in the description of L. inornatus are Bangana devdevi with 10 branched dorsal-fin rays. In the same publication, L. rubirostris was described with 10 branched dorsal-fin rays; however, all specimens examined here have 9 branched dorsal-fin rays. Roberts (1997) distinguished L. inornatus and L. rubirostris based on tuberculation (without rostral tubercles in L. inornatus vs. well-developed rostral tubercles in L. rubirostris ), snout color (snout without red in L. inornatus vs. red snout in L. rubirostris ), gill-raker counts (35 in L. inornatus vs. 43 in L. rubirostris ), and number of pairs of tuberculate lamellae on the palatal lamellar organ (5 in L. inornatus vs. 6 in L. rubirostris ).

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Material examined.— Labeo boga : India: Adyar basin: CAS SU 41167 , 1 , 74.3 mm SL, Tamil Nadu, Adyar River, Madras , 4 January 1941 . Myanmar: Irrawaddy basin: USNM 44756 , 1 , Kachin, Bhamao, Upper Burma, 29 June 1885. Labeo inornatus (all primary types) : Myanmar: Irrawaddy basin: CAS 88903 , 1 , Mandalay, Nyaung-U fish market, 21.20428N, 94.91388E, 13 April 1996; CAS 91772 , 1 , Mandalay, market, 21.96978N, 96.08748E, 13–25 April 1993; CAS 91774 , 9 , Mandalay, Nyaung-U market, 21.20428N, 94.91388E, 8 November 1996; CAS 91775 , 1 , Kachin, Myitkyina market (morning), 25.38648N, 97.39448E, 21–22 April 1996; CAS 91776 , 5 (of 7), Mandalay market, 21.96978N, 96.08748E, 13– 25 April 1993. Sittang basin: CAS 91773 , 6 , Bago, Sittang River at Taungoo or Taungoo Market , 18.94378N, 96.44738E, 7 April 1996. Labeo rubirostris (all primary types) : Myanmar: Tenasserim basin: CAS 91753 , 1 , Tenasserim River backwater (huge rocky ledge) midway between Kita or Htee-tah and Baowashung , 12 March 1992; CAS 91754 , 1 , Tenasserim River , upstream from Kita (Htee-tah), 8–9 March 1992; CAS 91755 , 1 , mainstream Tenasserim River between Kita or Htee-tah and Baowashung, March 1992; MNHN 1992.1043 , 1 (photographs), Tenasserim River , 12 March 1992; MNHN 1992.1044 , 2 (photographs), Tenasserim River , 12 March 1992 .

Figures

FIG. 10. Ventral view of Gymnostomus ariza, CAS 94081, 120.8 mm SL. Abbreviations: FM, fimbriae; RB, rostral barbel; RC, rostral cap. Photo by Z. Randall (FLMNH).

FIG. 11. Ventral view of Labeo boga, CAS SU 41167, 74.3 mm SL. Abbreviations: LL, lower lip; MB, maxillary barbel; PG, post-oral groove; RC, rostral cap; UL, upper lip. Photo by Z. Randall (FLMNH).