A study of Enterogyrus sp. (Monogenea) parasitizing the foregut of captive Pomacanthus paru (Pomacanthidae) in Georgia

Abstract

A species of Enterogyrus Paperna, 1963 (Monogenea: Ancyrocephalidae) parasitizing the foregut of a captive Pomacanthus paru (Pomacanthidae) in Georgia was studied in situ both histologically and with scanning electron microscopy. The worms are found at the junction of the esophagus and stomach and arrange themselves with their main body axis directed perpendicular to longitudinal folds in the foregut wall. They cling to host tissue principally by blades of the pair of large dorsal hamuli and apparently rely little on the action of the pair of small ventral hamuli and the 14 marginal hooks. It is argued that this adhesive attitude allows unrestricted movement when peristaltic waves move along the gut and the worm thereby maintains a stable footing. The body tegument is unusually thick (2 to 5 μm) for the worm's size. Dorsally it is smooth and devoid of microvilli. Ventrally it is thrown into transverse folds having small microvilli and unique round to oval papillae that measure up to 7 μm in diameter. Evidently the modified tegument is an adaptation to life in the foregut, possibly serving to protect worms from digestive enzymes. The study represents the first report of Enterogyrus from a marine host.