title: Two new cestode species ofTetragonocephalumShipley & Hornell, 1905 (Lecanicephalidea, Tetragonocephalidae) fromHimantura randalliLast, Manjaji-Matsumoto & Moore (Myliobatiformes, Dasyatidae) from the Gulf of Oman.
abstract: The original description of the genusTetragonocephalumwas published more than one hundred years ago but its taxonomic status was clarified only recently. To date, approximately 30 nominal species of this genus have been described, mostly from the northern Indian Ocean, but nearly half of them are invalid and only 14 species are recognized as valid. In the present study two new species ofTetragonocephalumare described from the spiral intestine ofHimantura randallifrom off Jod, on the northern coast of the Gulf of Oman.Tetragonocephalum sabaesp. n.is distinguishable from the valid species ofTetragonocephalumbased on number of proglottids (43-53), number of testes (42-50), and size of scolex (401-453×328-455), acetabula (87-109×72-116), mature proglottids (802-1,333×226-336), cirrus sac (92-160×103-154), and eggs (16-19×11-13).Tetragonocephalum salariisp. n.can be distinguished fromTetragonocephalum sabaesp. n.and all other valid species ofTetragonocephalumbased on number of proglottids (77-86). Furthermore, it differs from its congeners based on a combination of some characteristics, including the number of mature (3-7) and gravid (18-20) proglottids, the number of testes (30-38), and the size of acetabula (84-111×80-96), mature proglottids (497-833×334-403), gravid proglottids (1,036-1,482×440-575), testes (20-34×31-50), ovary (123-215×210-278), and eggs (24-45×13-21).
authors.affiliation: School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Enghelab Ave., Tehran, Iran.
authors.forename: Atabak Roohi
authors.initials: AR
authors.lastname: Aminjan
authors.affiliation: School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Enghelab Ave., Tehran, Iran.
authors.forename: Masoumeh
authors.initials: M
authors.lastname: Malek
keywords: Gulf of Oman; Himantura randalli; Tetragonocephalum sabae sp. n.; Tetragonocephalum salarii sp. n.