Diagnosis and interrelationships of fishes of the genus Channa Scopoli ( Teleostei : Channidae ) of northeastern India

Diagnostic characters of nine species of the genus Channa Scopoli of northeastern India are given. Examination of morphological and osteological characters revealed that the fish under study comprised two phylectic groups: marulius and gachua. The Marulius group is characteristic by having a very prominent V-shaped sharp isthmus, cephalic sensory pores arranged in groups, absence of scales on the lower jaw, a sharp prominent spinelike hypurapophysis, more branchial toothplates than epibranchial, and an elongated urostyle. The Gachua group is characterized by a U-shaped isthmus, cephalic sensory pores evenly arranged in a single row, the presence of one or two large cycloid scales on each side of the lower jaw, absence of a sharp prominent spine-like hypurapophysis, absence or presence of one tooth plate in the epibranchial, and absence of an elongated urostyle. An elongated bone is present in between two last hemal spines of all species examined. A key to known species of Channa of northeastern India is also given


INTRODUCTION
Genus Channa Scopoli, 1777 of the family Channidae is distinguished from other genera of the family in having long, soft dorsal and anal fins, scales on the head mostly cycloid and that on the body, mostly ctenoid, caudal fin rounded, curved lateral line.The genus is also characterized by a suprapharyngeal accessory respiratory organ which facilitates an air-breathing mode of life.Northeastern India is rich in swamps and lakes, and in Channid fauna.Under the All India co-ordinated project on air breathing fishes, Dehadrai (1975) made extensive studies on the cage culture of some of the species of this region.However, taxonomy and phylogeny of the Channid fishes of the region is poorly understood.
The Channidae are represented by 26 species, of which 23 occur in Asia and the rest in Africa (Musikasinthorn 2000).Hamilton (1822) described Ophiocephalus barca (now Channa) from Brahmaputra river near Goalpara, Assam.Hora (1921) listed C. punctatus (Bloch) from Chindwin basin, Manipur.Shaw and Shebbeare (1937) listed and gave brief descriptions of six species from northern Bengal, viz, C. amphibeus (McClelland), C. gachua (Hamilton), C. marulius (Hamilton), C. stewartii (Playfair) and C. striata (Bloch).Later reports on the fishes of Manipur by Menon (1952), and Menon (1954) did not include additional species of the genus.Sen (1985) listed and gave diagnostic characters of six species of the genus.Vierke (1991) described C. bleheri from Assam.Musikasinthorn (2000) described Channa aurantimaculata from Dibrugarh, Assam.Vishwanaths (2000 & 2002) works respectively on the fishes of Manipur and northeastern India did not include any additional species.Thus nine species of Channa are known from northeastern India.
In Distribution: Chel River basin, in the Brahmaputra River drainage of northeastern India and Bhutan.
Diagnosis: A species of Channa with lateral line scales 81, predorsal scales 17, maxilla extending beyond the posterior margin of eye, circumpeduncular scales 31, cephalic sensory pores single, two large scales, two large scales on each side of lower jaw under surface dorsal fin rays 50, anal fin rays 35, pectoral fin rays 15, pelvic fin rays six, cheek scales nine, body depth greatest at insertion of anal fin, body width greatest at insertion of pectoral fin.Snout somewhat pointed in dorsal view.Orbit not reaching dorsal contour of head in lateral view, upper and lower lips flattened.
Colour: In alcohol: body uniformly light brown, ventral surface whitish.Eleven vertical brown bars on upper half of body, extending below lateral line.Edges of dorsal, anal and caudal fins whitish.
Diagnosis: A species of Channa with lateral line scales 51-54, dorsal fin rays 45-47, anal fin rays 28-30, mouth large, eyes moderate, caudal fin rounded, cheek scales 8-12, upper jaw length more than 45% HL, 3-4 bars on the pectoral fin, pectoral fin rays 14-16, two large cycloid scales on each side of the lower jaw undersurface, pelvic fin length less than half the pectoral fin length, cephalic sensory pores single, maxilla extending clearly beyond posterior margin of eye, total vertebrae count 51 (Image 3), branchial tooth plate count 6.
Colour: Upper half of body dark brown to black with 7 or 8 large irregular orange blotches; pectoral fins with a black blotch at base and 5 vertical broad vivid black bands.
Remarks: It is endemic to Brahmaputra River basin.The report extends its distribution to Arunachal Pradesh.
Colour: Dorsal and flanks covered with numerous black spot, pectorals reddish with numerous black spots.
Remarks: The species is burrowing in habit, and lives in vertical burrows (Goswami et al. 2006).
Distribution: India: Assam, Brahmaputra basin, Arunachal Pradesh Diagnosis: A species of Channa with a slightly broad head, pelvic fin absent, sides of lower jaw have one large cycloid scale, 4-11 red or orange markings on caudal fin, eyes moderate, and caudal fin rounded, mouth large, 6-7 markings on the pectoral fin, maxilla and premaxillary processes extending beyond the posterior margin of the orbit, snout blunt, cephalic sensory pores single, lateral line complete with 46-50 scales, anal fin rays 25 and pectoral fin rays 14, total vertebral count 43, branchial toothplate count five.Tooth plates are present only on the outer side of the first gill arch and absent on the inner side of the same arch.
Colour: Grey to brown on sides, pale yellow to white ventrally, pectoral fin with 7 to 8 bars of alternating black and white bars.
Remarks: The report extends its distribution to Arunachal Pradesh.
Channa gachua (Hamilton) (Image 6) Ophicephalus gachua, Hamilton, 1822:68, 367 Distribution: Afghanistan in the west to Indonesia through South and Central Asia (Eschmeyer 2007) Diagnosis: A species of Channa with dorsal fin rays 32-37; lateral line scales 39-48, pelvic fin shorter than half the pectoral fin length, pectoral fin rays 15-17, anal fin rays 21-27, and caudal fin rays 12, maxilla and premaxillary process extending to vertical level of the posterior end of the orbit, one or two large cycloid scale on each side of lower jaw undersurface, Colour: Dorsal, anal and caudal fin margins white.There is often a large ocellus with a light edge on the last five dorsal rays in the young, body black getting lighter ventrally and abdomen creamish.
Diagnosis: A species of Channa with scales on cheek 4-6, pelvic fin longer than half pectoral fin length, pectoral fin with no bars, lateral line scales 35-40, dorsal fin rays 28-32, lower jaw with 3-6 canines behind a single row of villiform teeth, anal fin rays 19-21, body with two rows of bars, maxilla and premaxillary processes extending to vertical level of beyond the middle of orbit, sides of lower jaw with one large cycloid scale, cephalic sensory pores single, total vertebral count 35, branchial toothplate count eight.
Colour: Brown to dark green on flanks, pale yellow ventrally, several dark spots on body.
Diagnosis: A species of Channa with small black spots scattered on sides of body, dorsal fin rays 37-41, and anal fin rays 24-27, lateral line scales 45-53, eyes moderate, mouth large, pelvic fin about 1/3 as long as pectoral fin, 4-5 bars on the pectoral fin, head slightly broad with blunt snout, sides of lower jaw with two large cycloid scale, cephalic sensory pores single, total vertebral count 44, branchial toothplate count seven.
Colour: Light ash to dark brown.Almost all the scales with well defined circular black spots, pectoral fins spotted in zones.
Remarks: They are normally found only in the lower altitudes in the Barak and its tributaries.Often found feeding on young shoots of bamboo plants in swampy areas from rivers.
Diagnosis: A species of Channa with a large black ocellus on upper caudal fin base; 3 white spots on body.Dorsal fin rays 50-55, anal fin rays 31-35, sides of lower jaws with no scales, lateral line scales 60-70, 4-5 ocelli, presence of a sharp distinct pointed ridge of isthmus and anterior to it many longitudinal striae are present, lower jaw with 7 to 18 canines behind a single row of villiform teeth which deepens to 5 or 6 rows on symphysis, teeth on vomer, cephalic sensory pores not single, total vertebral count 62, branchial toothplate count 16.
Colour: A well-marked ocellus, brown surrounded by a ring paler than the ground-colour, on the upper half of the base of caudal fin.Five or six dark oval blotches on flank which terminate below lateral line, below lateral line between blotches pale yellow with reddish tinge distinct white spots scattered on body.An orange band running from eye to middle of caudal fin in Juveniles.
Remarks: This species is avoided in culturable waters because of its carnivorous habit.It grows to large size as for instance it has been reported that in Maharashtra this snake head grows up to 180cm in length and attains about 30kg in weight.
Distribution: Pakistan in the west through China, Thailand, Malaysia and Indonesia; (Eschmeyer 2007).
Diagnosis: A species of Channa with dorsal fin rays 42-45, anal fin rays 25-29, lateral line scales 55-65, mouth large, and lower jaw 4-7 canines behind a single row of villiform teeth, dorsal and anal fins slightly darker in color than body maxilla and premaxillary process extending to vertical level of beyond posterior margin of orbit, presence of a sharp pointed ridge at the mid-ventral part of isthmus and anterior to it many longitudinal striae are present, cephalic single pores not single, total vertebral count 54, branchial tooth plate count 13.
Colour: Body with chevron-shaped bars pointing forward, more distinct lower part.Dorsal fin with 5 inter-radial bands on the last 4 rays and 5 th to 7 th rays has one band at base.
Remarks: The materials examined agree with the characters involvement of more than one species.As Hamilton (1822) described the species from northern Bengal, which belongs to Ganga drainage, the specimens under the present study, which is within the range of its natural distribution, should be C. gachua sensu stricto.The specimens from Manipur also agree with the description of Brahmaputra specimens.
The morphological and osteological comparison of the present 9 species of Channa examined indicates that they constitute 2 phylectic groups each consisting of species sharing these morphological features almost completely.The two groups are marulius group and gachua group.The marulius group comprises of C. marulius and C. striata and gachua group comprises of C. amphibeus, C. aurantimaculata, C. barca, C. bleheri, C. gachua, C. punctatus and C. stewartii.The morphological similarity as seen among species in each group is sufficient to suggest that members of the same group are descendents from a common direct ancestral stock.
Morphologically the members of the marulius group is differentiated from the gachua group in having a prominent Vshaped sharp isthmus, grouped sensory pores arrangement, absence of big cycloid scales on the lower jaw whereas the members of gachua group have U-shaped isthmus, single sensory pores arrangement, presence of one or two big cycloid scales on each side of the lower jaw.
Gill rakers are absent in Channid fishes studied.Instead, branchial tooth plates are present on the gill arches Greenwood (1976).The number of tooth plates ranges from 5-16 in different Channid species.Marulius group has 3-4 numbers of branchial tooth plates in the epibranchial, presence of a prominent spine shaped hypurapophysis in the parhypural and presence of an elongated urostyle whereas the members of the gachua group has one or no branchial tooth plates in the epibranchial region, no spine shaped hypurapophysis and presence of a short urostyle.Tooth plates count are highest in marulius group.
Although C. bleheri is included in the gachua group, the species does not have pelvic fin.Another very significant character of the species is that tooth plates are present only on the outer side of the first gill arch and absent on the inner side of the same arch.Examination of more specimens would come out with interesting results.
In caudal skeleton of the genus studied, the last three caudal vertebrae support the caudal fin.The last fused centrum bears one parhypural, five hypural plates, one urostyle and one epural.The epural bone is thin, backwardly curved and located anteriorly to the urostyle.An elongated bone which has no connection with any of the centrum is present between the hemal spine of preuralcentrum 2 and preuralcentrum 3 (i.eanterior to parhypural).Distal tip of this bone supports the caudal-fin ray ventrally.The bone is referred as interhemal spine.The presence of interhemal spine is a very specific character found in all the species of Channa under study.The illustration of Day (Plate IC, 1909) the present study, detailed morphology and osteology of nine species, viz., Channa amphibeus, C. aurantimaculata, C. barca, C. bleheri, C. gachua, C. marulius, C. punctatus, C. stewartii and C. striata were carried out.Diagnostic characters and interrelationships of the species are presented here.A key to identification of the known species of Channa of the region is also included.98 gill arch of the left side of the specimens was taken.Plates starting from hypobranchial to epibranchial of the outer side were counted Channa amphibeus (McClelland) (Image 1) Ophicephalus amphibeus McClelland 1845: 274-279 (type locality: vicinity of Chail River, one of the tributaries of the Teesta at the foot of the Bouton mountains).Materials examined: 1 ex., (date unknown), 184.6mmSL, northern Bengal, India, coll.G.E. Shaw & E.O.Shebbeare, ZSI F 11435/1, neotype designated by P. Musikasinthorn 2000.