Cystacanths of Bolbosoma vasculosum in the black scabbard fish Aphanopus carbo, oceanic horse mackerel Trachurus picturatus and common dolphin Delphinus delphis from Madeira, Portugal

Abstract

Cystacanths of the acanthocephalan, Bolbosoma vasculosum Rudolphi 1819, were found to be encapsulated in the connective tissues of the viscera of the black scabbard fish, Aphanopus carbo and oceanic horse mackerel, Trachurus picturatusfrom Madeira, Atlantic Ocean. Juvenile worms were obtained from the intestine of a stranded common dolphin, Delphinus delphis, also from Madeira. Cystacanths were 11–15 mm long, with a proboscis of 18–19 longitudinal rows, eight hooks per row, and two sets of trunk spines. Overall, the morphology and dimensions of the proboscis, neck and trunk corresponded to previous descriptions. Scanning electron microscopy of the proboscis structures and trunk spines is provided for the first time. The prevalence of B. vasculosum in A. carbo increased with fish length. There were no statistical differences in the prevalence and intensity of infection between seasons. The intensity of infection was similar for male and female fishes, but there were significant differences in relation to length, longer fishes having heavier infections. Aphanopus carbo from Madeira represents a new host record and a new geographic location for B. vasculosum.