Two new marine species of Rhinebothrium (Cestoda: Rhinebothriidea) from stingrays from the Persian Gulf and Gulf of Oman.

The genus Rhinebothrium (Cestoda: Rhinebothriidea) comprises tapeworm species parasitizing elasmobranch hosts, particularly batoids. Despite numerous recent findings regarding the ecological importance of marine fish parasites throughout the world, the biodiversity of cestodes inhabiting fishes of the Persian Gulf and the Gulf of Oman remains understudied. Here, two new species of Rhinebothrium from stingrays from the Persian Gulf and Gulf of Oman are described: Rhinebothrium gossi sp. nov. and Rhinebothrium palmeri sp. nov. from Maculabatis arabica and Maculabatis randalli, respectively. However, each new cestode species is found with a lower frequency in the other host species, too. These new species were already subjected to a molecular analysis and the revealed genetic distinctiveness requires detailed morphological examinations at the species level. A combination of morphomeristic characteristics including body size, scolex features, proglottid morphology, and reproductive structures distinguish the new species from the other congeners. Although these new species are morphologically similar, however, they differ from each other in the number of testes (6-8 and 8-14), and bothridial loculi (50 and 42 in R. gossi sp. nov. and R. palmeri sp. nov., respectively). These findings contribute to our understanding of marine cestode diversity and underscore the importance of further research in this ecologically significant region.