Haplosporidian parasite in Diporeia spp. amphipods from the Great Lakes region, USA.

Light microscope observations of a haplosporidian in Diporeia spp. amphipods from Lakes Michigan and Huron, USA, found that the parasite spore is operculate and measures 8.1 microm in length and 6.1 microm in width. Round to amorphous sporocysts averaging 23.6 microm were present throughout hemal sinuses of infected amphipods. The number of developing spores within a sporocyst was highly variable and spores were observed in various stages of development. Electron microscopy revealed a lid over the operculum of developing spores and documented spores with fairly large and extensive ornamentation. This is the first haplosporidian reported in Diporeia spp. amphipods and only the second haplosporidian from freshwater species.