Abstract
Abstract Monogeneans Pricea multae naturally infested 42 of the 120 (35%) mackerel fish (Scomberomorus commerson) examined. For the first time, an infestation was discovered off the coast of Jubil in the Arabian Gulf of Saudi Arabia. Based on the structure clarified through light and electron microscopy of mounted specimens and molecular analysis of rDNA and measurements of this monogenean parasite was identified as P. multae. The tegumental surface of the parasite was characterized by tegumental ridges running transversally, generating folds in both the dorsal and ventral surfaces of the body at regular intervals. The study clarified the importance and function of the micro-structures, such as tegumental folds, perforations, sensory ganglia present on the parasite's surface, and the larger hamulus supported by a relatively unmodified internal spine. This monogenean parasite has adapted to its host infestation site uniquely.