Molecular identification and phylogenetic relationships of Coleoidea (Mollusca: Cephalopoda) from the Persian Gulf and Oman Sea reveals a case of cryptic diversity

The Persian Gulf and Oman Sea constitute one of the most important marine ecosystems and have many economically important aquatic species, including several coleoid cephalopods. Some coleoids are difficult to identify using traditional morphological characteristics. In this study, two mitochondrial fragments, cytochrome oxidase I (COI) and the large ribosomal subunit (16S rRNA), were used for identification of coleoid species in four regions in the northern Persian Gulf and Oman Sea. The study led to the identification of potential cryptic species of Sepia, Amphioctopus and Uroteuthis. Furthermore, Euprymna hyllebergi was reported for the first time from the Persian Gulf. A high diversity of Coeloidea was found in the study area. Mean intraspecific and interspecific nucleotide distances for COI were 0%–2% and 2%–7%, respectively, while these values for 16S rRNA sequences were 0%–1% and 1%–4%. Given the uncertainty about species identity and the high levels of intraspecific genetic diversity reported for some species in GenBank, a comprehensive global study will be needed to resolve the taxonomic status of several coleoid species.