Osteology of some catfishes of the genus Glyptothorax (Teleostei: Siluriformes) of northeastern India
W. Vishwanath 1, A. Darshan 2 & N. Anganthoibi 3
1, 3 Department of Life Sciences, Manipur University, Canchipur, Manipur 795003, India
2 Directorate of Coldwater Fisheries Research, Bhimtal, Uttarakhand 263136, India
Email: 1 email@example.com, 2 firstname.lastname@example.org,3 email@example.com
Blyth (1860) described the genus Glyptothorax, for which Bleeker (1862-63) designated Glyptosternon striatus McClelland as the type species. Glyptothorax is the most species-rich and widely distributed genus of the family Sisoridae. The genus has as many as 81 valid species (Ferraris 2007; Gopi 2007; Vishwanath & Linthoingambi 2007; Ng & Freyhof 2008; Ng & Kottelat 2008; Ng & Rainboth 2008). de Pinna (1996) casts doubt on the monophyly of the genus Glyptothorax, citing the lack of unambiguous synapomorphies to diagnose it. However, his phylogenetic analysis of the Sisoroidea still recovered a monophyletic Sisoridae.
Although there are reports on the osteological studies of Glyptothorax, viz., Gauba (1966) on G. cavia (Hamilton) and Diogo et al. (2002) on G. fukiensis (Rendahl), there are no reports of the comparative accounts on the osteology of the genus.
This study attempts to identify the variation of bones i.e., premaxilla, dentary, infraorbital series, frontal, vomer and articulation of complex centrum with remaining vertebral column in eight species of Glyptothoraxof north east India, viz. Glyptothorax botius (Hamilton), G. cavia (Hamilton), G. chindwinica Vishwanath & Linthoingambi. G. granulus Vishwanath & Linthoingambi, G. manipurensis Menon,G. ngapang Vishwanath & Linthoingambi, G. striatus (McClelland), andG. ventrolineatus Vishwanath & Linthoingambi. The results are presented in this study and discussed.
Material and Methods
Fresh specimens of Glyptothorax were collected from different areas of northeastern India. Measurements of antero-posterior length and lateral-extent of upper jaw tooth band follow Vishwanath & Linthoingambi (2007). Specimens were cleared and stained following Hollister (1934). Terminology and nomenclature of bones follow Chen & Lundberg (1995) and de Pinna (1996). Components of premaxillary bones are named as proximal, distal and posterior elements based on their positions.
Visible jaw structures of holotype of Glyptothorax burmanicus in ZSI Kolkata was also observed and compared.
Premaxilla: In six species, viz., Glyptothorax botius, G. granulus,G. manipurensis, G. ngapang,G. striatus, and G. ventrolineatus, the premaxilla (Figs. 1A & 1B) consists of four bony elements, i.e., a pair of medially located proximal elements (prp) and another pair of distal elements (dp), located lateral to the proximal element. The convex anterior margin of the distal element articulates with the corresponding concavity along the posterolateral margin of the proximal element. The distal element is firmly united to the proximal end by rigid connective tissue. However, in G. cavia and G. chindwinica, the premaxilla comprises of numerous distal (Fig. 1D: dp) and posterior elements (Fig. 1D: pop) in addition to a pair of proximal elements (Fig. 1D: prp). The distal and posterior elements are attached respectively to the lateral and the posterior parts of the proximal elements. All the subunits of the proximal, distal and posterior elements are tightly fastened by connective tissue to form the premaxilla. The sutures among the elements that comprise the premaxilla are not visible ventrally because the presence of numerous villiform teeth (Fig. 1C: vt) on this surface obscures it. Ventrally the premaxilla is seen as a single structure on the roof of the oral cavity (Fig. 1C).
Dentary: In the six species, viz., Glyptothorax botius, G. granulus,G. manipurensis, G. ngapang,G. striatus, and G. ventrolineatus, the anterior portion of the dentary is slender, with villiform teeth on its dorsal surface (Figs. 2A & 2B). However in G. cavia andG. chindwinica, the dentary is a stout, long, curved bone with a very broad anterior two-third portion. This broadness is manifested by a posterior extension of the tooth-bearing surfaces on the dentary (Fig. 2C & 2D: pdtp) which bears villiform teeth at its dorsal surface. Gauba (1966) also reported the tooth- bearing portion of the dentary to be very much flattened in G. cavia. The dentary tooth plate of G. burmanicus is also similar to that of G. cavia and G. chindwinica.
Posterior portion of Weberian lamina: The transverse process or parapophysis of complex centrum was named the Weberian lamina by de Pinna (1996). In the present study, all the examined species of Glyptothorax(except, G. cavia andG. chindwinica) have an extended posterior portion of Weberian lamina (Figs. 3B & 3C: ppwl) to the level of lateral margin of its anterior portion. In G. botius, there is a large rounded space between the articulation of the fifth parapophysis and the posterior portion of the Weberian lamina (Fig. 3D). Tight suturing is also observed at the adjoining parts of the space. In G. cavia andG. chindwinica, the lateral expansion of the posterior portion of Weberian lamina (Fig. 3A: ppwl) extends beyond the lateral margin of the anterior portion of the lamina, reaching almost to the distal tip of the parapophysis of the fifth vertebra.
Infraorbital: The number of infraorbital bones is variable. Glyptothorax botius has six infraorbital bones; of which the sixth is longest while the fifth, the shortest. Both G. ngapang and G. chindwinica have nine infra-orbital bones, while G. cavia has ten. In the remaining species, there are eight bones in the series. The thirdinfra-orbital in G. ngapang (Fig. 4B: io3) bears a broad ventral laminar process. Both G. cavia and G. chindwinica have a larger and broader body of the lacrimal (Fig. 4A: lac) when compared to other species examined.
Orbital notch: The orbital notch of the Glyptothorax is formed at the lateral margin of frontal as a shallow depression, forming an arc smaller than a semicircle (Fig. 5C: on). G. honghensis Li (Zhou & Zhou 2005: Fig. 6B), G. fukiensis (Diogo et al. 2002: Figs.1 & 2) and G. major (de Pinna 1996: Fig. 13) have also shallow orbital notches. However, in G. cavia and G. chindwinica, the notch is deep and forms an arc larger than a semicircle (Figs. 5A & 5B: on).
Vomer: The head of the vomer of Glyptothorax is edentulous and extended laterally along the entire length of the articular process of lateral ethmoid, reaching the articular facet for palatine at the lateral tip of each lateral ethmoid. In all the species examined (except in G. cavia and G. chindwinica), the anterolateral margin of the head of the vomer is concave resulting in the formation of a thin lateral process and another sharply pointed medial anterior tip (Fig. 6 B & C). In G. cavia and G. chindwinica, the head of vomer is very large and broad with roughly convex anterior margin (Figs. 5A & 5B: v; 6A).
Among the Siluriformes, the premaxilla of Glyptothorax (Tilak 1963; de Pinna 1996) and Bagarius Bleeker (Gauba 1962) is characteristic in having separate distal elements connecting laterally to the proximal element. Diogo et al. (2002) also reported the same structure in G. fukiensis (Rendahl). A subdivided premaxilla has also been reported in Glyptosternum reticulatum McClelland (Gauba 1969), and fragmentation of the distal element of premaxilla into tripartite or multipartite structures have also been reported in Euchiloglanis kishinouyei Kimura (de Pinna 1996). This study shows that structure of premaxilla in most of the examined species havea pair of medially located proximal elements and another pair of distal elements situated laterally. However, the premaxilla in G. cavia and G. chindwinica is markedly different, consisting of numerous posterior elements and distal elements in addition to proximal elements. Gauba (1966) recorded the premaxilla ofG. cavia as being generally segmented or fused to form an enormously broad band that extends a considerable distance posteriorly across the palate. However, he failed to notice the numerous individual tooth plates tightly attached by connective tissue.
The holotype of Glyptothorax burmanicus Prashad & Mukherji (Image 1A) has been examined. It has a central depression in the thoracic adhesive apparatus (Image 1B) and a premaxilla in the form of a broad patch with minute villiform sharp teeth and a dentary with broad teeth-bearing plate (Image 1C), the characters, similar to those of G. cavia and G. chindwinica.
Among the representatives of family Sisoridae, the posterior portion of the Weberian lamina is reported to extend along the anterior margin of the fifth vertebra in Bagarius, GagataBleeker, Glyptosternoids, Glyptothorax, Nangra (Day), Pseudecheneis Blyth and Sisor Hamilton (de Pinna 1996). This study indicates that the extension of the porterior portion of the Weberian lamina is not equal within the genus Glyptothorax. In the species under study, the posterior portion of the Weberian lamina is extended laterally to the level of the lateral margin of its anterior portion, except in case of G. cavia and G. chindwinica. A similar condition has been reported in G. major (de Pinna 1996: Fig. 26A) and in G. honghensis Li (Zhou & Zhou 2005: Fig. 6B). In G. cavia and G. chindwinica, the lateral expansion of the posterior portion of the Weberian lamina is long and reaches almost to the distal tip of the parapophysis of the fifth vertebrae.
Large variations in osteological characters of the Weberian lamina, infraorbital series, the shapes of the vomer and frontal have been observed among the members of the genus. However, pending examination of more species of the genus, it is not possible to establish the paraphyly of Glyptothorax. This study will help future workers to some extent in the study of phylogenetic relationships within Glyptothorax.
Glyptothorax striatus: Uncat., 2 exs., 79.7-83.0 mm SL, ICAR Complex for northeastern region, Barapani, Meghalaya, India, coll. B.K. Mahapatra; 31.x.2005, 4 exs. 40.2-123 .9 mm SL, Siren River, Rotung, East Siang District, Arunachal Pradesh, India, coll. K. Nebeshwar, MUMF 9040.
Glyptothorax cavia: 2 exs. 86.4-98.0 mm SL, left Bank of Kosi River, two furlongs down the confluence with the Arun River at Tribeni, Nepal, Kosi survey, F218/2; 2 exs., 82.8-80.3 mm SL, Same data, F219/2; 06.xi.2006, Uncat., 1 ex. 87.5 mm SL, Barak River, Tamenglong District, Manipur, India, coll. Kingson.
Glyptothorax manipurensis: 10.xii.1998, 10 exs.,69.0-104.0 mm SL, Barak river, Vanchengphai, Manipur, India, coll. K. Nebeshwar, MUMF 4029-4032.
Glyptothorax ventrolineatus: 15.i.2003, holotype, 85.8mm SL, Iril River, Ukhrul District, coll. I. Linthoingambi, MUMF L0221; 5 exs.,Paratypes, 85.1-94.5 mm SL, data same as holotype, MUMF L0222/5; 10.iv.2003, 4 exs., 67.2-83.2 mm SL. Lokchao River, Moreh, Chandel District, Manipur, India, coll. K. Nebeshwar and party, MUMF 4300/4.
Glyptothorax ngapang: 06.vi2001, holotype, 82.7mm SL, Iril River, Bamonkampu, Manipur, India, coll. I. Linthoingambi, MUMF 6131; paratypes, 9 exs, 61.7-99.5mm SL, same data as holotype, MUMF 6132; 10.iv.2003, 65.0-98.5mm SL, 10 exs., Lokchao River, Moreh (Indo-Myanmar border), coll. W. Vishwanath, MUMF 6141.
Glyptothorax granulus: 10.i.2004, holotype, 76.6mm SL, Iril River, Phungdhar, Ukhrul District, Manipur, India, coll. I. Linthoingambi, MUMF 6151; 06.vi.2003, paratypes, 10 exs., 61.7-76.6mm SL, same data as holotype, MUMF 6152; 12.xi.2003, 1ex., 96mm SL., Iril River, Urup, Manipur, India (Chindwin basin), coll. Linthoi, MUMF 9991; 03.iv.2004, 10exs., 80.5-89.8 mm SL Lokchao river, Moreh (Indo-Myanmar border), coll. W. Vishwanath, MUMF 6156.
Glyptothorax chindwinica: 26.viii.2002, holotype, 145.4mm SL, Iril River, Urup, Manipur, India, coll. I. Linthoingambi, MUMF 6366; 03.iv.2004, 115.6-145.5 mm SL, paratypes, 4 exs., Lokchao River, Moreh (Indo-Myanmar border), Chandel District, Manipur, India, coll. W. Vishwanath, MUMF 6368; 15.i.2004, 5 exs, 100.2-123.6 mm SL, Thoubal River, Nongpok Keithelmanbi, Thoubal District, Manipur, India, coll. I. Linthoingambi, MUMF 6369.
Glyptothorax burmanicus: holotype, 100.8mm SL, Sankha, a large hill-stream, midway between Kamaing and Mogaung, Myitkyina District, Upper Myanmar, coll. Dr. B.N. Chopra, ZSI F10877/1.
Glyptothorax botius: 16.iii.2006, 75.2mm SL, Dibru River, Dibrugarh, Assam, India, coll. Santosh, MUMF 9520.
Bleeker, P. (1862-63). Atlas ichthyologique des Indes Orientales Néêrlandaises, publié sous les auspices du Gouvernement colonial néêrlandaises. Tome II. Siluroides, Chacoïdes et Hétérobranchoïdes. Amsterdam, 112pp.
Blyth, E. (1860). Reports on some fishes received chiefly from the Sitang River and its tributary streams, Tenasserim Provinces. Journal of the Asiatic Soceity of Bengal 29: 138-174.
Chen, X. & J.G. Lundberg (1995). Xiurenbagrus, a new genus of Amblycipitid catfishes (Teleostei: Siluriformes), and phylogenetic relationships among the genera of Amblycipitidae. Copeia 1995(4): 780-800.
de Pinna, M.C.C. (1996). A phylogenetic analysis of the Asian catfish families Sisoridae, Akysidae, and Amblycipitidae, with a hypothesis on the relationships of the Neotropical Aspredinidae (Teleostei: Ostariophysi). Fieldiana Zoology (New series) 84: 1-83.
Diogo, R., M. Chardon & P. Vandewalle (2002). Osteology and mycology of the cephalic region and pectoral girdle of Glyptothorax fukiensis (Rendahl, 1925), comparison with other sisorids, and comments on the synapomorphies of the Sisoridae (Teleostei: Siluriformes). Belgium Journal of Zoology 132(2): 95-103.
Ferraris, C.J., Jr. (2007). Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of Siluriform primary types. Zootaxa 1418: 1-628.
Gauba, R.K. (1962). The endoskeleton of Bagarius bagarius (Hamilton), part I- The skull. Agra University Journal of Research11(1): 75-90.
Gauba, R.K. (1966). Studies on the osteology of Indian sisorid catfishes II. The skull of Glyptothorax cavia. Copeia4: 802-810.
Gauba, R.K. (1969). The head skeleton of Glyptosternum reticulatumMcClelland & Grifith. Monitore Zoologico Italiano 3: 1-17.
Gopi, K.C. (2007) Pisces, pp.115-131. In: The Director, Zoological Survey of India, Kolkata (ed.), Conservation Area Series, 32, Fauna of Kudremukh National Park (Karnataka). Zoological Survey of India, Kolkata.
Hollister, G. (1934). Clearing and dying fishes for bone study. Zoologica 12: 89-101.
Menon, A.G.K. (1999). Checklist- Freshwater fishes of India. Records of the Zoological Survey of India, Miscellaneous Publications, Occasional Paper 175, xxviii+366pp.
Misra, K.S. (1976). The Fauna of India and The Adjacent Countries, Pisces 3. Teleostomi: Cypriniformes: Siluri, (2nd Ed.), Zoological Survey of India, Calcutta, xxi+367pp.
Ng, H.H. & J. Freyhof (2008). Two new species of Glyptothorax(Teleostei: Sisoridae) from central Vietnam. Zootaxa 1873: 11–25.
Ng, H.H. & M. Kottelat (2008). Glyptothorax rugimentum, a new species of catfish from Myanmar and western Thailand (Teleostei: Sisoridae). The Raffles Bulletin of Zoology 56(1): 129-134.
Ng, H.H. & W.J. Rainboth (2008). Glyptothorax coracinus, a new species of hillstream catfish from Cambodia (Teleostei: Sisoridae). Zootaxa 1839: 60–68.
Thomson, A.W. & L.M. Page (2006). Genera of the Asian catfish families Sisoridae and Erethistidae (Teleostei: Siluriformes). Zootaxa 1345: 1-96.
Tilak, R. (1963). The osteocranium and the Weberian apparatus of the fishes of the family Sisoridae (Siluroidea): a study in adaptation and taxonomy. Zeitschrift für Wissenschaftliche Zoologie169: 281-320.
Vishwananth, W. & I. Linthoingambi (2007). Fishes of the genus Glyptothorax Blyth (Teleostei: Sisoridae) from Manipur, India, with description of three new species. Zoos’ Print Journal 22(3): 2617-2626.
Zhou, W. & Y.W. Zhou (2005). Phylogeny of the genus Pseudecheneis (Sisoridae) with explanation of its distribution pattern. Zoological Studies 44: 417–433.