||Environmental Research Lab., Gulf Breeze, FL. ;Battelle Pacific Northwest Labs., Sequim, WA. Marine Research Lab. ;California Univ., Santa Cruz. Long Marine Lab.;Great Barrier Reef Marine Park Authority, Townsville (Australia).
The report describes coccidian merozoites (asexual stages) in the exocrine pancreas and oocysts in the gut epithelium of hardy heads, Atherinomorus capricornensis (Woodland) (family Atherinidae) collected at Heron Island, Queensland, Australia, during the pre-ICOPA (International Congress of Parasitology) workshop held 16-24 August 1986. Examination of the pancreatic merozoites by electron microscopy revealed conoids, micronemes and rhoptries which are unique to the phylum Apicomplexa. As many as four individuals were observed within a single host cell. Although it was usually not possible to determine the type of cell infected, some were intact enough to be identified as pancreatic acinar cells. No parasites undergoing multiple synchronous fission (schizogony) were observed, but dividing pairs attached at the posterior end were frequently seen. Because of inadequate fixation, detection of sporocyst sutures or Stieda bodies in the oocysts by electron microscopy were not possible.