[Plasmodia of lemurs in Madagascar]." Lemur macaco macaco from Ambanja region was found polyparasitized by four different species of Plasmodium: --Plasmodium coulangesi recently described by lepers et al. (1989). --P. bucki n. sp.: its main differential characterisitics are the large numvber (32) of merozoites produced in mature schizonts and the stippling, resembling Maurer''s dots, in an hypertrophied pinkish erythrocyte. --P. percygarnhami n. sp. (= P. girardi sensu Uilenberg, 1970 pro parte and sensu Garnham et Uilenberg, 1975 pro parte) producing 20 merozoites in mature schizonts and developing inside a deformed corpuscle (holly leaf-shaped or sometimes sea-urchin-shaped) which may also become decolourized when parasitized by older stages. --(?) Plasmodium lemuris: gametocytes are very large (11 microns x 7 micron); the parasitized erythrocyte is much hypertrophied (+/- 10 microns), distored and of a pinkish colour; one schizont only, possibly exo-erythrocytic, was found. The authors hypothesized this parasite to be a Haemoproteid. The analysis of published data led the authors to make the following modifications to the nomenclature previously established: --Plasmodium girardi Buck et al., 1952, sensu Garnham, 1966, sensu Uilenberg, 1970 parte and sensu Garnham and Uilenberg, 1975 pro parte, is refered to as Plasmodium sp., for stages developing in the blood of Lemur fulvus fulvus. The taxon P. percygarnhami is to be employed for stages developing in L. m. macaco and P. girardi Buck et al., 1952 for those developing in Lemur fulvus rufus. --Plasmodium foleyi Buck et al., 1952, sensu Garnham and Uilenberg, 1975 in L. f. fulvus is named Plasmodium uilenbergi n. sp., P. folleyi being a parasite of L.f. rufus. Excluding P. lemuris which probably does not belong to the genus Plasmodium, the morphological analysis led to individualize 7 species, in the three species of Lemurs studied. A phenomenon of ""vicariance"" thus appears, similar to what is known for the african Rodent Plasmodia, but with a more pronounced speciation. The vicariant species form a pair constituted of: --on the one hand a small species developing in a red blood cell of normal size, P. girardi in L.f. rufus, P. sp. in L.f. fulvus, P. percygarnhami, with also, P. coulangesi, in L. m. macaco; --on the other hand a large species determining an hypertrophy of the erythrocyte, P. foleyi in L.f. rufus, P. uilenbergi in L.f. fulvus and P. bucki in L.m. macaco."