Two new species of the lecanicephalidean cestode genus Hexacanalis Perrenoud, 1931 from butterfly rays in the Persian Gulf and Gulf of Oman, Iran

The cestode order Lecanicephalidea predominately parasitizes batoid fishes. The genus <i>Hexacanalis</i> (family Lecanicephalidae) is defined by the presence of six osmoregulatory canals and an antero-posteriorly U-shaped ovary. This genus currently includes three recognized species distributed across the Indian Ocean and the western Pacific Ocean. Until now, no records have documented its occurrence in the Persian Gulf or the Gulf of Oman. In this study, specimens of <i>Hexacanalis</i> were collected and examined for the first time from the genus <i>Gymnura</i> in both the Gulf of Oman and the Persian Gulf. Based on morphological characteristics, two new species of this genus are described. <i>Hexacanalis mariae</i> n. sp., collected from the Gulf of Oman, is distinguished from <i>H</i>. <i>abruptus</i> by several features, including the distribution pattern of vitelline follicles, an armed cirrus covered with microtriches, and a ventral position of the vagina relative to the cirrus sac. It also differs from <i>H</i>. <i>folifer</i> by the reduced extent of the velum in its craspedote proglottids and from <i>H</i>. <i>pteroplateae</i> by lacking gravid proglottids and by the position of the vagina. <i>Hexacanalis arshai</i> n. sp., identified from the Persian Gulf, closely resembles <i>H</i>. <i>folifer</i> in strobilar appearance but differs in having proglottids with a uterus containing eggs and in overall body length. Given the high host specificity of lecanicephalideans, the occurrence of two distinct <i>Hexacanalis</i> species-one in the Persian Gulf, from hosts for which molecular identification was not possible and considered here as <i>G</i>. cf. <i>poecilura</i>, and another in the Gulf of Oman parasitizing butterfly rays identified molecularly as <i>Gymnura</i> cf. <i>poecilura</i> 2-may indicate the presence of sibling species within the <i>G</i>. <i>poecilura</i> species complex in the northwestern Indian Ocean. This possibility is discussed in detail herein.