en fish disease fish disease پژوهشي Orginal research papers <span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">Narrow-barred Spanish mackerel (<i>Scomberomorus commerson</i>) is one of the most important commercial fish species in the Persian Gulf and Oman Sea. Parasites of the genus <i>Hysterothylacium</i> (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 <i>Hysterothylacium</i> on <i>S. commerson </i>from April 2012 to December 2013. The morphological identification of <i>Hysterothylacium</i> 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 <i>Hysterothylacium persicum</i></span></span></span><span dir="RTL" lang="AR-SA" style="font-size:11.0pt"><span arial="" style="font-family:"><span style="color:black">.</span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black"> Based on the morphological analysis and sequencing, the Hysterothylacium specimen was described as <i>H. persicum</i>. It is the first morphological and molecular identification of <i>H. persicum</i> in <i>S. commerson</i> from Iran. A combination of morphological description with a molecular technique seems to be the best practice for identifying anisakid larvae.</span></span></span> Scomberomorus commerson, Hysterothylacium persicum, Morphology, Molecular identification, Persian Gulf 695 704 http://jifro.ir/browse.php?a_code=A-10-335-14&slc_lang=en&sid=1 M. Adel miladadel85@yahoo.com 100319475328460056792 100319475328460056792 Yes Department of Aquatic Animal Health and Diseases, Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran H.R. Azizi hr_azizi@yahoo.ca 100319475328460056793 100319475328460056793 No Department of Pathobiology, Faculty of Veterinary Medicine, University Shahrekord A. Nematolahi anematolahi@yahoo.com 100319475328460056794 100319475328460056794 No Department of Health and Food Quality Control, Faculty of Veterinary Medicine, University Shahrekord, Iran E. Ebrahimzade elahemir@yahoo.com 100319475328460056795 100319475328460056795 No Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad M. Dadar dadar.m77@gmail.com 100319475328460056796 100319475328460056796 No 5 Razi Vaccine and Serum Research Institute (RVSRI)