DNA BARCODING TO RESOLVE MORPHOLOGICAL AMBIGUITY OF YELLOWFIN SNAPPER, Lutjanus xanthopinnis FROM TERENGGANU

Abstract

Lutjanus species belong to the family Lutjanidae, where some of the species, such as L. lutjanus, L. vitta, and L. johnii, are common species in Malaysia. The fish, also known as snapper, can be discovered in abundance in most fish landings, including at Terengganu. Lutjanus xanthopinnis, commonly known as yellowfin snapper, is another fish commonly found in Malaysian water, especially Terengganu. However, their morphological characteristics were doubted, as it is hard to distinguish by morphometric and meristic identification alone. This study was conducted by collecting 100 Lutjanid samples with mixed freshness grades from 11 locations consisting of four districts: Besut, Kuala Nerus, Kuala Terengganu, and Marang, Terengganu. These 11 locations consisted of fish landing ports, fish stalls, and fish markets in the identification using the Cytochrome Oxidase 1 (CO1) gene marker for the five morphological ambiguous samples. The initial external examination of the samples based on the colour of the stripes led to the identification of the 30 Lutjanid samples as L. xanthopinnis. Further identification of 30 Lutjanid samples via 40 morphometrics and nine meristic characters led to only 25 individuals from the 30 samples fully confirming their identity as L. xanthopinnis. However, five of the samples have several gill rakers, soft dorsal, and anal fin rays that are not similar yet overlap with the previous reports. Hence, these five samples were taken to undergo molecular identification via DNA barcoding using the CO1 gene. The Neighbour Joining Method phylogenetic tree with the Kimura-2 Parameter (K2P) model revealed that the five samples were differentiated into three clades, which were L. xanthopinnis, L. vitta, and L. lutjanus. Molecular identification for the five samples also revealed that three samples were identified as L. xanthopinnis. In contrast, the remaining two were identified as L. vitta and L. lutjanus, respectively, with 99% to 100% similarity. The study has demonstrated that molecular identification via DNA barcoding is a valuable complementary tool to morphological identification, enabling more accurate species identification. It is recommended that fresh samples and more samples are collected from other states. Furthermore, the use of DNA barcoding should be continued in species validation to achieve the highest possible level of accuracy.