A simple yet useful criterion based on external markings and/or number of dorsal spines is currently used to differentiate two congeneric archer fish species Toxotes chatareus and Toxotes jaculatrix.Here we investigat...A simple yet useful criterion based on external markings and/or number of dorsal spines is currently used to differentiate two congeneric archer fish species Toxotes chatareus and Toxotes jaculatrix.Here we investigate other morphometric and meristic characters that can also be used to differentiate these two species.Principal component and/or discriminant functions revealed that meristic characters were highly correlated with pectoral fin ray count,number of lateral line scales,as well as number of anal fin rays.The results indicate that T.chatareus can be distinguished from T.jaculatrix by having a greater number of lateral line scales,a lower number of pectoral fin rays,and a higher number of anal fin rays.In contrast,morphometric discriminant analyses gave relatively low distinction:76.1% of fish were ascribed to the correct species cluster.The observed morphometric differences came from the dorsal and anal spines lengths,with T.chatareus having shorter dorsal and longer anal spines than T.jaculatrix.Overall,meristic traits were more useful than morphometrics in differentiating the two species;nevertheless,meristics and morphometrics together provide information about the morphological differentiation between these two closely related archer fishes.展开更多
基金Project supported by the Malaysian Government through Universiti Kebangsaan Malaysia Science Fund(No.04-01-02-SF0124)the fellowship Schemes of Universiti Kebangsaan Malaysia(Nos.UKM-OUP-FST-2009 and UKM-MI-OUP-2010)
文摘A simple yet useful criterion based on external markings and/or number of dorsal spines is currently used to differentiate two congeneric archer fish species Toxotes chatareus and Toxotes jaculatrix.Here we investigate other morphometric and meristic characters that can also be used to differentiate these two species.Principal component and/or discriminant functions revealed that meristic characters were highly correlated with pectoral fin ray count,number of lateral line scales,as well as number of anal fin rays.The results indicate that T.chatareus can be distinguished from T.jaculatrix by having a greater number of lateral line scales,a lower number of pectoral fin rays,and a higher number of anal fin rays.In contrast,morphometric discriminant analyses gave relatively low distinction:76.1% of fish were ascribed to the correct species cluster.The observed morphometric differences came from the dorsal and anal spines lengths,with T.chatareus having shorter dorsal and longer anal spines than T.jaculatrix.Overall,meristic traits were more useful than morphometrics in differentiating the two species;nevertheless,meristics and morphometrics together provide information about the morphological differentiation between these two closely related archer fishes.
