The order Haemosporidia gathers many protozoan parasites which are known to infect many host species and groups. Until recently, the studies on haemosporidian parasites primarily focused on the genus Plasmodium among a wide range of hosts. Genera, like the genus Hepatocystis, have received far less attention. In the present study, we present results of a survey of the diversity of Hepatocystis infecting bats and monkeys living in a same area in Gabon (Central Africa). Phylogenetic analyses revealed a large diversity of Hepatocystis lineages circulating among bats and monkeys, among which certain were previously observed in other African areas. Both groups of hosts harbor parasites belonging to distinct genetic clades and no transfers of parasites were observed between bats and monkeys. Finally, within each host group, no host specificity or geographical clustering was observed for the bat or the primate Hepatocystis lineages. A large diversity of hepatocystis parasites infects central African bats and monkeys. However, no switching of these parasites between bats and monkeys was observed in confined environment, where these two host groups could live together. [ABSTRACT FROM AUTHOR]