First Record of Redfin Emperor Monotaxis heterodon (Lethrinidae) from Indian Waters with Molecular Confirmation

Lethrinidae is one of the commercially important fish in India. The present study provides detailed morphometric, meristic characters and colour patterns of Monotaxis heterodon (Bleeker, 1854). The unique key characters of M. heterodon are having 24 vertebrae, the teeth patterns of both the jaws having molar teeth present in both jaws 4+3 but 6 canines in upper jaw and 4 canine teeth in lower jaw. Specifically, this species has dark brownish lips, no black spots at base of soft dorsal fin and 13 scale rows below lateral line to anal-fin origin. The COI gene sequence and phylogenetic analysis confirmed that Monotaxis heterodon and Monotaxis grandoculis were genetically distinct species and conform the distribution of M. heterodon in Indian Exclusive Economic Zone. In addition, molecular analysis using partial mitochondrial COI gene suggests that genetic distance within M. heterodon group was 0.32% of group mean distance between M. heterodon and M. grandoculis was 8.37%. Further, the present study revealed the range of extension of its known geographical distribution in addition to the ichthyofaunal biodiversity of southeast coast of India.