FURTHER TAXONOMICAL NOTES ON CHAGUNWS CHAGUNIO (HAMILTON) FROM BOON VALLEY

摘要

The present communication deals with the taxonomical analysis of the medium carp Chagunim chagunio (Hamilton) from Doon Valley, in the light of earlier works. It has been found more adaptive to the rheophilic environment of Song and Suswa (more frequent in Suswa) in Eastern Doon. The customary meristic and morphometric characterizations reaffirm the earlier findings with some enlargement in ranges. The characters of special attention are those of sexual dimorphism, where besides confirming the earlier records some hitherto unrecorded characters are the highlights of discussion, particularly with reference to profile of dorsal fin in males and females. In males, when folly spread, the dorsal fin exhibits convexity at the summit with 2nd, 3rd and 4thdivided rays being longer (1.40-1.78 in Head Length), whereas in females the summit margin is cut concave. The ratios with reference to length of barbels in Snout Length and Head Length and also of Length of base of Dorsal fin in Total Length and Head Length are strikingly distinguishing in males and females, not elaborated in earlier works, are also the contributions out of the present work. The analysis of distributional pattern in Doon Valley goes more in favour of Suswa river stretch wherein Chagunius chagunio has found satisfactory venturing grounds.