Molecular confirmation of the occurrence of <i>Elysia</i> cf. <i>tomentosa</i> (Mollusca: Heterobranchia) in the Persian Gulf

<p>The molluscan fauna of the Persian Gulf has recently been relatively well documented, yet there are few records of heterobranch sea slugs (opisthobranchs) from the Arabian parts and no report from the Iranian waters. Here we report for the first time the occurrence of one of these molluscs in the northern Persian Gulf (Bandar Abbas, Iran). Sacoglossan specimens were collected in association with the seaweed, <i>Caulerpa sertularioides</i>. Since morphological attributes were not adequately reliable for species identification, molecular approaches were carried out. Maximum-likelihood and Bayesian Inference analysis of partial DNA sequences of the mitochondrial cytochrome <i>c</i> oxidase subunit I (COI) locus were used for DNA barcoding of large-bodied specimens of <i>Elysia</i>. All Persian Gulf specimens were genetically confirmed as <i>Elysia</i> cf<i>. tomentosa</i> sp. 5, one of at least five morphologically similar but genetically distinct species in the taxonomically challenging and unresolved <i>E. tomentosa</i> complex. This species has previously been recorded only from Australia and Thailand and our finding adds another distant point to the geographic distribution of this species.</p>