COCCIDIAN INTESTINAL PARASITES IN THE PRIAPULIDAE (PRIAPULIDA)

Four relatively uncommon members of the family Priapulidae (Priapulida ) from very different parts of the world were examined to determine th e presence of a parasitic coccidian in their midgut. The parasite was found in three of those priapulid species, Priapulopsis bicaudatus, P. australis, and Halicryptus higginsi, but not in the fourth one, Priap ulus tuberculatospinosus. Using electron-microscopy techniques, we com pared parasites of the different species with one another and with a p arasite of Priapulus caudatus investigated by McLean in 1984. All of t hese parasites apparently belong to the same species and are likely to be Alveocystis intestinalis, a coccidian first described by Beltenev from P. caudatus and H. spinulosus. The present work greatly expands t he geographical range of Alveocystis intestinalis and documents an unc ommon case of low host specificity in eimeriid coccidians.