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 wvnath@gmail.com, 2 achom_darshan@yahoo.com,3 angannong@gmail.com

 

 

Date of publication (online): 26 October 2010

Date of publication (print): 26 October 2010

ISSN 0974-7907 (online) | 0974-7893 (print)

 

Editor: Heok Hee Ng

 

Manuscript details:

Ms # o1874

Received 24 October 2007

Final received 22 July 2010

Finally accepted 03 September 2010

 

Citation: Vishwanath, W., A. Darshan & N. Anganthoibi (2010). Osteology of some catfishes of the genus Glyptothorax (Teleostei: Siluriformes) of northeastern India. Journal of Threatened Taxa 2(11): 1245-1250.

 

Copyright: © W. Vishwanath, A. Darshan & N. Anganthoibi 2010. Creative Commons Attribution 3.0 Unported License.JoTT allows unrestricted use of this article in any medium for non-profit purposes, reproduction and distribution by providing adequate credit to the authors and the source of publication.

 

Author Details: A. Darshan is a Post-Doctoral Fellow of Department of Biotechnology, Govt of India and is at present attached to the Directorate of Coldwater Fisheries Research, Bhimtal, Uttarakhand. He is working on the phylogeny of catfishes based on classical and molecular techniques.

N. Anganthoibiis a Research scholar, registered for PhD degree in the Department of Life Sciences, Manipur University. She is working on the inventory of the catfishes of northeastern India and their phylogenetic analysis.

W. Vishwanath is a Professor in the Department of Life Sciences, Manipur University. His field of specialization is fish and fisheries. He is presently engaged in taxonomy and systematics of freshwater fishes of northeastern India.

 

Author Contribution: The study: AD - survey, collection, morphometric and anatomic study of catfishes of northeastern India and their phylogenetics; NA - survey, collection, morphometric and anatomic study of catfishes of northeastern India and their phylogenetics; WV - supervision of taxonomy and phylogeny of freshwater fishes of northeastern India.

Current paper: AD - detailed examination of collections, comparision with specimens in ZSI and preparation of drawings; NA - detailed examination of the collections of Glyptothorax in MUMF and osteological studies; WV - supervision of the work, interpretation of the results and comparison with available literature.

 

Acknowledgements: The work is supported by National Bureau of Fish Genetic Resources (an ICAR Institute), Lucknow, Projecton inventory and phylogeny of catfish superfamily Sisoroidea of Northeast India.

 

 

Abstract: The morphology of the premaxilla, dentary, Weberian lamina, infraorbital series, vomer and frontal bones were observed in eight species of Glyptothorax of northeastern India.  In G. botius, G. granulus, G. manipurensis, G. ngapang, G. striatus and G. ventrolineatus, the premaxilla consists only of proximal and distal tooth plates, the anterior portion of the dentary is slender and its dorsal surface bears villiform teeth, the lateral extension of posterior portion of Weberian lamina terminates at the level of the lateral margin of its anterior portion, and the frontal has a shallow orbital notch.  In G. cavia and G. chindwinica, the premaxilla consists of proximal, distal and posterior elements on the roof of the oral cavity; the anterior portion of the dentary bears posterior extension of dentary tooth-plate; the lateral extension of the posterior portion of Weberian lamina extends almost to the distal tip of the fifth parapophysis; there are nine or ten infraorbital bones with a longer and broader body of the lacrimal; greatly enlarged vomerine head; and frontal bears a deep orbital notch.  The jaw structure of G. burmanicus is discussed.

 

Keywords: Glyptothorax,osteology, Sisorid fish, tooth plates

 

Abbreviation:  MUMF - Manipur University Museum of Fishes; dp - distal element; prp - proximal element; pop - posterior element; vt - villiform teeth; Pdtp - posterior extension of dentary bony tooth-plate; wl - Weberian lamina, ppwl-posterior portion of Weberian lamina; cc - complex centrum; vc5 - fifth vertebral centrum; ns4 - fourth neural spine; sop - spine of supraoccipital; lac- lacrimal (first infraorbital); ion-  infraorbital1-10; Af - anterior cranial fontanelle; afp - articular facet for palatine; bo - bassioccipital; e - mesethmoid; epo - epeotic; exo - exoccipital; f - frontal; le - lateral ethmoid; n - nasal; on - orbital notch; pf - posterior cranial fontanelle; po - prootic; pt - pterotic; pts - pterosphenoid; scl - supracleithrum; so - supraoccipital; s - sphenotic; v - vomer.

 

 

 

For figures, images  -- click here

 

Introduction

 

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.

 

 

RESULT

 

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).

 

 

Discussion

 

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.

 

Comparative Materials

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.

 

 

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