Phylogenetic analyses reveal that Schellackia parasites (Apicomplexa) detected in American lizards are closely related to the genus Lankesterella: is the range of Schellackia restricted to the Old World?

Abstract

Background: Schellackia species have been described from the blood of reptiles distributed worldwide. Recently, Schellackia species detected in European and Asian lizards have been molecularly characterized. However, parasites detected in American host lizards remain uncharacterized. Thus, phylogenetic affinities between Old and New World parasite species are unknown.Methods: In the present study, we have morphologically and molecularly characterized hemococcidian parasites (sporozoites) that infect three lizard hosts from North America and two from South America.Results: In total, we achieved 12 new 18S rDNA gene sequences of hemococcidian parasites infecting New World lizard hosts. On the one hand, by the microscopic examination of the smears we identified Schellackia golvani (ex Anolis carolinensis) and Schellackia occidentalis (ex Uta stansburiana and Sceloporus occidentalis) in some samples, but the phylogenetic analysis indicates that all 18S rDNA sequences are distant from Schellackia species found in Old World lizards. In fact, the hemococcidian parasites detected in New World lizards (including S. occidentalis and S. golvani) were closely related to genus Lankesterella. Consequently, we suggest these two species to be included within the genus Lankesterella.Conclusions: Life history traits of hemococcidian parasites such as type of host blood cell infected, host species or number of RB were not valid diagnostic characteristics to differentiate the parasites between the genera Schellackia and Lankesterella. Indeed, lankesterellid parasites with different number of refractile bodies had close phylogenetic origin. Based on the phylogenetic results we suggest a systematic revision of the American hemococcidia. Our recommendation is to include the species formerly described in genus Schellackia (i.e., S. golvani and Schellackia occidentalis) that infect American lizard into genus Lankesterella (Lankesterellidae).