DNA barcoding on cardinalfishes (Apogonidae) of Thoothukudi coast

Cardinalfishes belongs to the family, Apogonidae is cryptic in nature that often shows taxonomic ambiguity through conventional taxonomy. It is globally accepted that mitochondrial DNA marker i.e., Cytochrome C Oxidase (COI) can be used to resolve these taxonomic uncertainties. In the present study, the DNA barcode was developed using COI marker for the two species of cardinalfishes (Archamia bleekeri and Ostorhinchus fleurieu) collected from Thoothukudi coast. Results showed that the distance values between the two species are higher than that of within the species. The Cytochrome C Oxidase subunit I (COI) gene showed more number of transitional pairs (Si) than transversional pairs (Sv) with a ratio of 2.4. The average distance values between A. bleekeri and O. fleurieu were 3.825, 4.704, 5.145, 7.390, 8.148, 7.187 and distance values among the A. bleekeri and O. fleurieu were 4.777 and 3.660, 3.583 and 6.509 respectively using K2P parameter. The average nucleotide frequency calculated were A= 26.9%, T(U)= 24.3%, C= 21.95% and G= 26.8%. The estimated GC content of A. bleekeri and O. fleurieu was (49.9%) and (47.6%) respectively and the average GC content was found to be 48.75%. Phylogenic trees were constructed individually for the two species using MEGA 6.0 software and the Neighbour-Joining tree showed distinct clusters shared by the species of same genera. In conclusion, the present study developed DNA barcode database for the two species of cardinal fishes that can be used for taxonomic purposes for these species.