A multivariate approach for developing a dichotomous key for identification and differentiation of Puntius (Osteichthyes: Cyprinidae) species in Sri Lanka

Sri Lanka is a global biodiversity hot spot with a rich freshwater fish fauna. Out of a total of 82 freshwater fish species, the genus Puntius represents 16 species (19.5%). Ambiguities exist in taxonomic identification of the different Puntius species. Hence, in this study a dichotomous key was developed using morphometric and meristic characters to identify and differentiate the Puntius species. Altogether 421 specimens representing different Sri Lankan Puntius species were collected from 38 sites at four different altitude ranges from five major river basins in Sri Lanka. Fifteen meristic characters, four coded variables and twenty three morphometric characters were recorded for each specimen and characters were analysed using principal component analysis (PCA).

Six principal components were extracted for meristic characters and coded variables that explained 81.5% of the cumulative variance in the dataset. Two meristic characters (number of transverse scales and number of post dorsal scales) and four coded variables (nature of the lateral line, position of mouth, number of barbels and nature of dorsal fin spines) were the variables that contributed most to the variance of the six principal components identified. The six characters were sufficient in isolation to develop a dichotomous key for all, except for two species. Two principal components extracted only for morphometric characters were also able to differentiate Puntius species but not to the same level as meristic characters and therefore, they contributed less to the dichotomous key developed here. Based on this approach, 15 Puntius species could be differentiated unambiguously.

Keywords: Meristic, morphometric, principal component analysis, Puntius.

doi :10.4038/jnsfsr.v38i1.1722

J.Natn.Sci.Foundation Sri Lanka 2010 38 (1):15-27