evolutionary and biological basis. It is known from many written historical sources that P. vivax malaria was endemic in the wetlands of England from the 1500s until the 20th century. It is suspected that this disease was introduced by the Romans sometime before 400 AD. It seems likely that it remained endemic in these areas at least up to 1000 AD. A study in Senegal of 25 strains isolated there suggests that P. falciparum underwent a major (60-fold) population expansion of ~20,000-40,000 years ago. A population study based on isolates from several countries suggests that distinct clustering of continental populations - Africa, Southeast Asia and Oceania - has occurred. Within these grouping there has been some further clustering - West Africa versus East Africa, Thailand versus Cambodia. No distinction was identified between isolates from Mali and Burkina Faso. Host range Because of the number of species parasited by Plasmodium further discussion has been broken down into following pages: Plasmodium species infecting humans and other primates Plasmodium species infecting mammals other than primates Plasmodium species infecting birds Plasmodium species infecting reptiles Criteria used for speciation The vertebrate host is the first criterion used for speciation and may be sufficient alone to determine the subgenus as in Ophidiella and Vinckeia. The morphological features of the parasite itself most commonly used to describe a species include the number of pigment granules, the degree of encirclement of the host nucleus, the size of the parasite, the degree of host nucleus displacement and the degree of host cell enlargement. List of species Plasmodium accipiteris Plasmodium achiotense Plasmodium achromaticum Plasmodium acuminatum Plasmodium adleri Plasmodium aegyptensis Plasmodium aeuminatum Plasmodium agamae Plasmodium alaudae Plasmodium alloelongatum Plasmodium anasum Plasmodium anomaluri Plasmodium arachniformis Plasmodium ashfordi Plasmodium atheruri Plasmodium audaciosum Plasmodium auffenbergi Plasmodium aurulentum Plasmodium australis Plasmodium attenuatum Plasmodium azurophilum Plasmodium billbrayi Plasmodium billcollinsi Plasmodium balli Plasmodium bambusicolai Plasmodium basilisci Plasmodium beaucournui Plasmodium beebei Plasmodium beltrani Plasmodium berghei Plasmodium bertii Plasmodium bigueti Plasmodium bioccai Plasmodium biziurae Plasmodium blacklocki Plasmodium booliati Plasmodium bouillize Plasmodium brodeni Plasmodium brasilianum Plasmodium brumpti Plasmodium brygooi Plasmodium bubalis Plasmodium bucki Plasmodium buteonis Plasmodium caloti Plasmodium capistrani Plasmodium caprae Plasmodium carmelinoi Plasmodium cathemerium Plasmodium caucasica Plasmodium cephalophi Plasmodium cercopitheci Plasmodium chabaudi Plasmodium chiricahuae Plasmodium circularis Plasmodium circumflexum Plasmodium clelandi Plasmodium cnemaspi Plasmodium cnemidophori Plasmodium coatneyi Plasmodium coggeshalli Plasmodium coluzzii Plasmodium colombiense Plasmodium columbae Plasmodium cordyli Plasmodium coturnixi Plasmodium coulangesi Plasmodium cuculus Plasmodium cyclopsi Plasmodium cynomolgi bastianelli Plasmodium cynomolgi