Narrow-barred Spanish mackerel (Scomberomorus commerson) is one of the most important commercial fish species in the Persian Gulf and Oman Sea. Parasites of the genus Hysterothylacium (Ascaridoidea: Anisakidae) are common ascaridoid nematodes of fish-eating birds and sea mammals. The aim of this study is to identify morphological and molecular characteristics of the Hysterothylacium on S. commerson from April 2012 to December 2013. The morphological identification of Hysterothylacium specimens (n=10) was performed based on characteristic features, measurements and comparison with other publications. Larvae were counted, fixed in 70% ethanol and cleared in lactophenol for 48 h for identification. The molecular species description was based on a polymerase chain reaction (PCR) of sequences comprising ITS-1 and ITS-2. After the blast of nucleotide sequences, with the other recognized sequencing recorded in the GenBank, the most similarity was observed to Hysterothylacium persicum. Based on the morphological analysis and sequencing, the Hysterothylacium specimen was described as H. persicum. It is the first morphological and molecular identification of H. persicum in S. commerson from Iran. A combination of morphological description with a molecular technique seems to be the best practice for identifying anisakid larvae

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