Discrimination of six flathead fishes (Family: Platycephalidae) based on otolith morphology and morphometric features

A taxonomic study on Kumococius rodericensis (Cuvier, 1829), Grammoplites suppositus (Troschel, 1840), G. scaber (Linnaeus, 1758), Sorsogona tuberculata (Cuvier, 1829), Platycephalus indicus (Linnaeus, 1758) and Cociella crocodilus (Cuvier, 1829) (family Platycephalidae) commonly occurring along the coast of India, was conducted to identify the traits which can easily differentiate the species. The study was based on samples (n=203) collected from landing centers of maritime states situated along the East and West coast of India from August 2015 to April 2016. In shape analysis no significant difference was observed at 95% level of confidence (p<0.05) between Left and right otolith and between male and female, so only the left otolith of all specimens considered for analysis for all species. The otolith of S. tuberculata was most rounded by 1.79 score among other species while otolith of C. crocodilus was more flat by 2.55 score. K. rodericensis and G. scaber had roundness score of more than 2.20 while G. suppositus and P. indicus had roundness scores less than 2.20. All species showed values of number of end points (points at the end of one pixel thick open branches) were zero except C. crocodilus that had a number of end points equal to 5, which showed that the periphery of otolith had five grooves larger than 1 pixel. The study disclosed a specific morphological and morphometric based characters of otolith that can be used to adjudicate the ambiguity in the flathead species.