eISSN: 2672-7226 © Penerbit UMT Journal of Sustainability Science and Management Volume 15 Number 4, June 2020: 34-44 CYTOCHROME OXIDASE I GENE REVEALS POTENTIAL CRYPTIC DIVERSITY OF DOUBLEWHIP THREADFIN BREAM, Nemipterus nematophorus (BLEEKER, 1854) IN PENINSULAR MALAYSIA TUN NURULAIMI MAT JAAFAR* 1 , NURLIYANA SHARIFFUDDIN 1 , SALWANI ABDULLAH 1 , AHASAN HABIB 1,2 AND TAN MIN PAU 3 1 Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia. 2 Department of Fisheries and Marine Sciences, Noakhali Science and Technology University, Noakhali–3814, Bangladesh. 3 Institue of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia. *Corresponding author: tun_aimi@umt.edu.my Submitted: 27 August 2019 Accepted: 16 April 2020 Introduction Malaysia is one of the biodiversity hotspots in Southeast Asia (Lim et al., 2016). Its inland and coastal waters are known as rich fsh breeding habitats, and about 82 % of Malaysia’s national fsh harvest comes from inshore fsheries (Lim et al., 2016). The studied species, the doublewhip threadfn bream or Nemipterus nematophorus (locally known as ikan kerisi dwiflamen), is a bottom-living coastal fsh confned to tropical and sub-tropical waters of the Indo-West Pacifc region (Hung et al., 2017).This species has been receiving increasing attention because of its commercial importance, specifcally in the manufacture of surimi and surimi-based products (Santos & Ng, 1993). Nemipterus nematophorus is available throughout the year and very popular with Malaysian consumers (Imtiaz et al., 2016). Threadfn breams are an important demersal fshery resource along the Malaysian coast. They are mainly exploited by small commercial trawlers in depths up to 50 m. The existence of rich resources of threadfn breams on the continental shelf beyond 50 m depth, especially in the 75 to100 m belt along different parts of the shelf, often form 75 % of the trawl catch (Joseph, 2000). However, threadfns bream catches are rarely reported because they are hard to identify (Pawar et al., 2011), and misidentifcation is a common problem at fsh jetties and markets (Imtiaz et al., 2016). Commercially important marine species may be particularly at risk in the loss of genetic diversity because population boundaries are often diffcult to identify, migration patterns are not well described, and harvest may preferentially target specifc population segments. Population genetic analysis is the best method to evaluate genetic divergence and plays vital role in getting information about the conservation Abstract: Genetic variations and differences among three Nemipterus nematophorus populations in Peninsular Malaysia were evaluated based on partial sequence of the mitochondrial Cytochrome Oxidase I gene (654bp). Among the 30 individuals sampled, 12 putative haplotypes were detected, and 58 % (7) of the haplotypes were unique with a high level of haplotype diversity (H= 0.802) and low nucleotide diversity (π = 0.0114). The constructed neighbour joining (NJ) phylogenetic tree based on haplotypes showed two clusters with specimens from Kelantan and Melaka grouped in the same cluster, while Terengganu samples formed an isolated cluster. These two clusters were separated with maximum 2.9 % nucleotide divergence. Analysis of Molecular Variance (AMOVA) revealed a high level of F ST value (F ST = 0.16; p=0). Pairwise F ST value showed signifcant differences between the Kelantan and Melaka populations from the one in Terengganu. The Terengganu population, although morphologically identical with specimens from Kelantan and Melaka, consisted of a genetically discrete taxon. This study revealed that there is potential cryptic diversity of N. nematophorus in Peninsular Malaysia. These fndings are important to provide a scientifc framework for sustainable management strategies and conservation of commercially important fshery resources in the region. Keywords: COI, cryptic diversity, Nemipterus nematophorus, Peninsular Malaysia. http://doi.org/10.46754/jssm.2020.06.004