Plasmodium octamerium n. sp., an Avian Malaria Parasite from the Pintail Whydah Bird Vidua macroura*

SYNOPSIS. A new species of avian malaria parasite is described from the pintail whydah Vidua macroura, a very small African finch of the weaver bird family (Ploceidae). Its structure has been studied chiefly in the canary, to which it is easily transmissible by blood inoculation. Since the segmenters most often produce 8 merozoites, the name Plasmodium octamerium n. sp. is proposed. Other characteristics include sexual stages which are usually elongate, often slender, and do not displace the host cell nucleus, and gametocytes indistinguishable from those of many species of Haemoproteus. Erythrocytes are the only blood cells parasitized. The new species resembles Plasmodium fallax in many respects, but gives rise to fewer merozoites and the asexual forms are smaller. Blood-induced infections are also of strikingly different type in some host species. Among susceptible host species are several kinds of finches, pigeons, quail, young chicks, chukars, tree and song sparrows. In most of these hosts infections are mild, but some tree sparrows die as the result of blood infection, and chukars usually die because of massive invasion of the capillary endothelium of the brain by exoerythrocytic forms. These are of the gallinaceum type and may be quite large, producing hundreds of merozoites. Exoerythrocytic stages were sought but not found in other host species.