A MORPHOMETRIC STUDY OFf CHANNA PUNCTATA ( BLOCH ) ( PISCES : CHANNIDAE )

The present paper deals with the clinal variation in the species Channapunctata (Bloch). While studying the morphology of this species, authors came across a few interesting specimens. The meristic counts of these specimens are almost similar to that of C. punctata (Bloch) but diff~rs interestingly in colour pattern being having lateral yellow stripes on either side Day. .( 1875-78) also observed brilliant orange bands in immature specimens of C. marulius. Willey (1908) and Deraniyagala (1929) noticed such stripes in the juveniles of Channa punctata (Bloch). Howeverr, Hora (1921), Jones (1946) and Mi~ra (1962) overlooked these colour variations among Channa species. An endeavour has been made here to ascertain the systematic identity of such morphovariant which are distinctly unique particularly in respect of colollr pattern, based on the morphometric evaluation of different characters.


INTRODUCTION
The genus Channa Scopoli (1777), forms a commercially important group of fishes, comprising of eight species from Indian waters (Jayaram, 1981).Day (1878) described only one species under this genus and e~ght species under th~ genus Ophiocephatus.Misra (1962) reported four species from India and Pakistan.HO 'Yever, Menon (1974) noticed on1y six species under this genus from the Gangetic Plain.
The present paper deals with the clinal variation in the species Channapunctata (Bloch).While studying the morphology of this species, authors came across a few interesting specimens.The meristic counts of these specimens are almost similar to that of C. punctata (Bloch) but diff~rs interestingly in colour pattern being having lateral yellow stripes on either side Day..(1875-78) also observed brilliant orange bands in immature specimens of C. marulius.Willey (1908) and Deraniyagala (1929) noticed such stripes in the juveniles of Channa punctata (Bloch).Howeverr, Hora (1921), Jones (1946) and Mi~ra (1962) overlooked these colour variations among Channa species.An endeavour has been made here to ascertain the systematic identity of such morphovariant which are distinctly unique particularly in respect of colollr pattern, based on the morphometric evaluation of different characters.

M.A:TERIAL & METHODS :
The present study is based on 103 specimens of Channa punctata (24 mm to 200 mm SL) present in the National Zoological collections of E.R.S./Z.S.I., Shillong collected from different localities of ~orth Eastern Region of India.The specimens with lateral yellow stripes were compared with the specimens of different size grolJps at the intervals of 20 mm SL.A total of 23 characters were mensurated and subjected to statistical analysis by calculating the mean, standard 'deviation and standard error.The data were pooled together for students '1' test as a result, probability at 95CYo confidence intervals were determined (after Simpson et. al., 1960).Further. the nunlerical interpretations for each character were compared by enlploying geometrical expression proposed by Dice and Leraas (1936) and adopted by Hubbs and Hubbs (1952).In this method for each ~haracter the range, mean, one standard deviation and one standard error on either side of the nlean were delineated on the graphs.
I t is seen that except predorsal distance, prepelvic distance, base of anal fin, length of caudal fin in standard length andowidth of head in length of head in respect of all other characters the two populations have a probability of less than S'}'u.From the Dice Diagram it would appear that there is a gradual variation in respect of the length of head.preanaL pre-pelvic, pectoral-pelvic, pelvic-anal distance, base of dorsal fin, height of body.length of pectoral fin.length of caudal peduncle in  From the data analysed for thi~ populatiqn. it can be seen that except the pelvicanal distance.base oof dorsal fin.base of anal fin.length of pelvic fin in stanOdard length; height of head in length of head and the height 01' dorsal fin in its base in respect of other 17 characters, the two populations have probability of less than ?%. .1.Popula/ioll 0/2() to JO In/1l SL ".';.7/ to t)() 111111 SL.
The two populations are similar in respect of 17 characters inasmuch ar the prohability is less than 5~4,.But differs in respect oof base of dorsal fin.base of anal fin.length of caudal fin~ length of caudal• peduncle.in standard length; height" of dorsal fin in its base and length of caudal peduncle in height of caudal peduncle.
Fruill the graphs I-VIII, X-XVII alJd Dice diagranl A & D in each.it is seen that the 16 characters vary gradually according to size group.It is also observed that the length of snout and the interorbital width are having maximum variation among these populations.

Populatioll
The two JXlpulations °are sinlilar statistically in• respect 0.' 19 characters in the fact Ihal their probability is less th'an S'X •• The other four characters which in the twu popUlations differ are prc(lnal distance in standard length.width of head in its length.height of dorsal nn in its base and leng-t.h ,of (:audal peduncle in its height.FrOlll the graphs fI-111.\/ -VIII.X-X III. and X\/-XVIII) and  i4;YO From the data analysed, it is seen that these two populations differ in 11 characters having the probability of IO<Yo-99CYu.In rcspe<:t of other 12 characters they are similar.From the Dice diagram it would appear that there is agraduaJ variations in respect of 15 characters according to size group (Graph I-VI.VIII.IX-XII.XIV, XVI .. XVIII and Dice diagram A & F in each).The eye diameter.length of snout and the interorbital width exhibit the maximum variation .

H•H LH •
• 6.It is found that except pr~anal distance, pectoral-pelvic distance and height of body in standard length: width of head.height of head in length of head and length of caudal peduncle in its height, in respect of other 17 characters these two populations are having probability of less than 50/0.
The graphs (I-III, V, VII-IX, XI-XIV, XVI-XVIII) and Dice diagram (A & Gin each), indicate a gradual variation in respect of 14 characters and the maximum variations are notic~d in respect of prepelvic distance, prepectoral distance"length of pectoral fin, eye diameter and the interorbit~l width.

DISCUSSION
The comparative statistical analysis of morphometric characters nlensurated from seven different size groups of a species under the genus Channa.clearly indicates that despite certain morptiological variations al) the specimens studied belong to the same species.Generally, the specific status of various species under this genus is determined, based on the meristic characters such as the number of dorsal fin rays.pectoral fin rays, anal fin rays.lateral line scales and the predorsal scales.So much so, the present species under study belong to Channa pUllctata (Bloch) since all the specimens examined have constantly 28-30 dorsal fin rays, 16-17 pectoral fin rays, 19-23 anal fin rays.37-40 lateral line scales and 12: 13 pt:edorsal scales irrespective of their size groups.
However, the statistical evaluation of 23 morphometric characters reveals that the first group (20-30 mm SL) varies significantly in respect of various characters from the other size groups.Further, the first group can be considered as a separate species if compared with only the size range of 111-130 mm SL as out of 23 morphometric characters 11 characters indicate the probability of IOo/u-99'Xl.But it is a well known fact that the biological conclusion can not simply be determined in terms of numerical interpretation.Thus the numerical data delineated (1) the graphs would perhaps indicate that the significance of variations in respect of different morphometric character analysed are not species specific but a sort of intraspecific variations.These variations are clinal as revealed from the Di~e diagram.However. the magnitude of variation itself varies in diff~rent characters since the divergence is more in respect of eye diameter.interorbital width and the length of snout as compared to other characters (Graphs XVI, XVIII, XVIII).
Morphologically. the specimens belonging to the size group (20-30 mnl SL) are• distinct in as much as they have lateral golden stripes extending from the snout, through eyes to middle of the caudal peduncle.Whereas the specimen above 30 mm SL do not have any such stripe.However.Day {1875-7R) obse•rved brilhant standard length: height of head in length of head at:1d the length of caudal peduncle in height of caudal peduncle (Graphs I.III.IV.VI-V•III.X. XI.XIII.XV-XIX.Dice diagram A & B in each).
Graphs I-VI.VIII, X-XIV.XVI-XIX and Dice diagranl A and C in each.indicate that out of 19 characters 16 characters represent gradual variations .

DBSL
ABBREVIATION USED IN THE GRAPH: