Molecular Identification of Uroteuthis chinensis (Gray, 1849) (Myopsida: Loliginidae) from Selat Nasik, Belitung Island Using DNA Barcoding of the COX1 Gene

Uroteuthis chinensis is a commercially important squid species in Indonesia, particularly in the Bangka-Belitung waters, where it holds high economic and ecological significance. Due to its high export quality, it is a key commodity for the region's fisheries and marine sectors. Belonging to the Loliginidae family, which comprises approximately 50 species, Uroteuthis chinensis exhibits overlapping populations with closely related species in the Western Pacific, complicating morphological identification. DNA-based approaches, particularly mitochondrial Cytochrome C Oxidase Subunit I (COX1) gene analysis, offer a more accurate and efficient alternative for species identification. DNA was extracted from Bangka squid specimens using the gSYNCTM DNA Extraction Kit, and the COX1 gene was amplified using PCR with MyTaq HS Red Mix. Electrophoresis and BLASTn analysis confirmed the species identity with 99-100% similarity to Uroteuthis chinensis. Phylogenetic analysis, using the neighbor-joining method with 1000 bootstrap replicates, revealed that the Belitung Island population clusters within the same clade as Uroteuthis chinensis, with minimal genetic divergence (0.004). A total of 446 nucleotide base pairs were analyzed using the primers LCO1490 and HCO2198. These results confirm the evolutionary relationship of Uroteuthis chinensis and demonstrate the effectiveness of DNA barcoding for cephalopod species identification. This study contributes to biodiversity monitoring and provides a molecular reference for Uroteuthis chinensis in Indonesia. The sequence data has been deposited in the NCBI GenBank to support further research on marine biodiversity.