This would place an upper limit of for the evolution of the genus "Leucocytozoon". Leucocytozoon caulleryi is a species of the genus "Leucocytozoon", a genus of parasitic alveolates. Leucocytozoon (or Leukocytozoon) is a genus of parasitic alveolates belonging to the phylum Apicomplexa. Some species are known to spread the protozoan blood parasite "Leucocytozoon tawaki" in penguins. Blood parasites include "Trypanosoma" species, and a "Leucocytozoon" first identified in this waxwing. He helped to establish a new genus "Leucocytozoon" (but did not give the name). "Leucocytozoon" while describing parasites he called "Leucocytozoon danilewskyi" from several common birds. A species of haemosporidian, "Leucocytozoon", has been noted in specimens from Malaysia. The genus "Leucocytozoon" is thought to have evolved in the Oligocene. "Culicoides" midges transmit "Leucocytozoon" protozoa to poultry birds. The leucocytozoon blood parasite "L. caprimulgi" is rare in the European nightjar. In birds the "Haemoproteus" and "Leucocytozoon" species rarely change transmission area. Blood parasites "Leucocytozoon" of the family Plasmodiidae have been noted in the lung tissues. They found "Leucocytozoon" hepatic megaloschizonts in up to 95% of the sampled organisms. The majority of the species lie within three genera&colon; "Haemoproteus", "Leucocytozoon", and "Plasmodium".