Otoliths as taxonomic tool to identify catfishes of the genus Mystus (Teleostei: Bagridae) from India

To contribute to the clarification of taxonomy of bagrid catfishes belonging to the genus Mystus, the lapillus otoliths of five species (Mystus armatus, M. malabaricus, M. cavasius, M. gulio and M. tengara), using various otolith shape indices such as circularity, ellipticity, rectangularity and form factor were compared. Among the indices studied, rectangularity and form factor bestowed maximum F-ratio of 49.223 and 30.621, respectively, contributing maximum to species discrimination. The F-ratio for circularity, ellipticity, rectangularity, form factor and roundness were found to be 4.154, 28.735, 30.621, 49.223 and 14.58, respectively. The shape indices studied varied significantly among the five species. Cross validation by discriminant analysis of otolith shape data explained 100% variability by the first four functions. The jack-knifed classification matrix identified that the original groups are correctly classified to an extent of 68.6%. The description provided in this article will serve as a baseline database for bagrid otolith of the genus Mystus.