Haemocystidium spp., a species complex infecting ancient aquatic turtles of the family Podocnemididae: First report of these parasites in Podocnemis vogli from the Orinoquia

Abstract

The genus <i>Haemocystidium</i> was described in 1904 by Castellani and Willey. However, several studies considered it a synonym of the genera <i>Plasmodium</i> or <i>Haemoproteus</i>. Recently, molecular evidence has shown the existence of a monophyletic group that corresponds to the genus <i>Haemocystidium</i>. Here, we further explore the clade <i>Haemocystidium</i> spp. by studying parasites from Testudines. A total of 193 individuals belonging to six families of Testudines were analyzed. The samples were collected in five localities in Colombia: Casanare, Vichada, Arauca, Antioquia, and Córdoba. From each individual, a blood sample was taken for molecular analysis, and peripheral blood smears were made, which were fixed and subsequently stained with Giemsa. The prevalence of <i>Haemocystidium</i> spp. was 1.55% (n = 3/193); all infected individuals belonged to <i>Podocnemis vogli</i> (Savanna Side-necked turtle) from the department of Vichada. This is the first report of <i>Haemocystidium</i> spp. in Colombia and in this turtle species. The phylogenetic analysis of a mitochondrial c<i>ytb</i> fragment revealed <i>Haemocystidium</i> spp. as a monophyletic group and as a sister taxon of <i>Haemoproteus catharti</i> and the genus <i>Plasmodium</i>. <i>Haemocystidium</i> spp. are difficult to identify by morphology only. As a result, it is possible that some of the taxa, such as <i>Haemocystidium</i> (<i>Simondia</i>) <i>pacayae</i>, represent a species complex. The parasite found in our study is morphologically indistinguishable from <i>Haemocystidium</i> (<i>Simondia</i>) <i>pacayae</i> reported in Peru. However, the new lineage found in <i>P. vogli</i> shows a genetic distance of 0.02 with <i>Hae. pacayae</i> and 0.04 with <i>Hae. peltocephali</i>. It is proposed that this divergent lineage might be a new species. Nevertheless, additional molecular markers and ecological features could support this hypothesis in the future.