Half a century after its discovery, new insights on Anthemosoma garnhami (Sporozoa, Piroplasmida): morphology, molecular characterisation and phylogenetic position.

Here, we report new insights on the erythrocytic murine parasite Anthemosoma garnhami, which was first described from Ethiopia in 1969. Its classification has been debated for years, as this parasite presents some intermediate characters between the Haemosporidia and the Piroplasmida. Based on electron-microscopy, immunological, biochemical and drug sensitivity studies, it was finally assigned to the piroplasms, in the family Anthemosomatidae. In 1985, Anthemosoma sp. was reported from Namibia, and since then, no investigation has involved this parasite. We re-examined the original material, illustrate the blood stages with a set of coloured microphotographs and performed a morphometric analysis. As no type material was designated at the time of the original description, we designate syntypes. This study provides also the first molecular data on A. garnhami with the amplification and sequencing of two genes: the nuclear 18S small subunit ribosomal RNA and the mitochondrial cytochrome c oxydase subunit I. The phylogenetic analyses of both genes confirm that A. garnhami belongs to the Piroplasmida and appears on its own new branch distinct from both Babesids and Theilerids. This result supports the placement of the genus Anthemosoma in its own family but also invalidates the order Anthemosomida. Being paraphyletic with Babesia, the conundrum about the systematics of the piroplasms is discussed as well as the records, the hosts and the possible vectors of Anthemosoma spp.