Morphological and molecular identification of Cainocreadium pteroisi (Digenea: Opecoelidae) isolated from Pterois miles (Perciformes: Scorpaenidae) in the Red Sea, Egypt.

Abstract

Fifteen specimens of the devil firefish, Pterois miles (Bennett) (Perciformes: Scorpaenidae), were collected from the Red Sea off Safaga, Egypt, between November 2022 and April 2024, and examined for parasitic infections. Parasitological analyses included light and scanning electron microscopy (SEM) for morphology, alongside partial sequencing of the 28 S rDNA gene for molecular characterization. A single digenean species was found in the intestine of 12 out of 15 (80%) P. miles specimens, identified as Cainocreadium pteroisi (Nagaty & Abdel Aal, 1962) Durio & Manter 1968 (Opecoelidae: Hamacreadiinae). Light microscopy revealed an elongated, fusiform body with key features such as a spherical oral sucker, larger ventral sucker, oblique testes, lobed ovary, and lateral vitellarium. SEM provided further details, showing intricate muscle structures in the ventral sucker. Phylogenetic analysis confirmed the placement of the parasite within the genus Cainocreadium. This study reports a southward range extension of C. pteroisi within the Red Sea and provides clarification and confirmation of its host as P. miles, which was likely misidentified as P. volitans in the original description. Furthermore, it provides new insights through SEM imaging and DNA sequence data for the species.