Molecular and morphological characterization of a haemogregarine in the alligator snapping turtle, Macrochelys temminckii (Testudines: Chelydridae)

Characterization and identification of haemogregarine hemoparasites (Apicomplexa: Adeleina: Hepatozoidae) in natural populations of Mauremys leprosa leprosa and M. leprosa saharica from Morocco

Distribution, prevalence and parasitaemia of apicomplexan parasites of the genus Haemogregarina were studied in 858 freshwater turtles (735 Mauremys leprosa leprosa and 123 Mauremys leprosa saharica) throughout 30 localities from Morocco. Blood smears were collected from the turtles and partial 18S rRNA sequence data used to infer genetic diversity and phylogenetic relationships. Of the 858 individuals analyzed by microscopy 22.7% were infected, from 16 M. leprosa leprosa localities. Individuals of M. leprosa saharica sampled south of the High Atlas Mountains were not infected, probably due to the absence or rarity of the leech vectors in these localities. Within M. leprosa leprosa, we did not identify any patterns between geography and prevalence, which varied between 10% (Oued Nfiss) to 100% (Oued Tassaout). Five distinct genetic lineages were identified, indicating the likely presence of multiple species of haemogregarines, one of which probably corresponds to Haemogregarina stepanowi. Mixed infections were also detected. Additional studies are needed to better understand the ecology and epidemiology of this parasite in turtles, as well as the host-parasite relationship with their definitive hosts, leeches.

Cytochrome c oxydase I phylogenetic analysis of Haemogregarina parasites (Apicomplexa, Coccidia, Eucoccidiorida, Haemogregarinidae) confirms the presence of three distinct species within the freshwater turtles of Tunisia

Species of Haemogregarina are apicomplexan blood parasites that use vertebrates as intermediate hosts. Due to limited interspecific morphological characters within the genus during the last decade, 18S rRNA gene sequences were widely used for species identification. As coinfection patterns were recently reported from nuclear molecular data for two sympatric freshwater turtles Mauremys leprosa and Emys orbicularis from Tunisia, our objectives were to design COI specific primers to confirm the presence of three distinct species in both host species. Blood samples were collected from 22 turtles, from which DNAs were extracted and used as templates for amplification. Following different rounds of PCR and nested PCR, we designed specific Haemogregarina COI primers that allowed the sequencing of nine distinct haplotypes. Phylogenetic Bayesian analysis revealed the occurrence of three well-differentiated sublineages that clustered together into a single clade. Based on pairwise genetic distances (p-distance), we confirmed the occurrence of three distinct but phylogenetically closely related species coinfecting M. leprosa and E. orbicularis in the same aquatic environments. Our results demonstrate that the use of fast evolving genes within Haemogregarina will help to investigate the parasite diversity within both intermediate vertebrate and definitive invertebrate hosts, and to assess the evolution, historical biogeography and specificity of haemogregarines.

Haemogregarines and Criteria for Identification

Simple Summary

Taxonomic classification of haemogregarines belonging to Apicomplexa can become difficult when the information about the life cycle stages is not available. Using a self-reporting, we record different haemogregarine species infecting various animal categories and exploring the most systematic features for each life cycle stage. The keystone in the classification of any species of haemogregarines is related to the sporogonic cycle more than other stages of schizogony and gamogony. Molecular approaches are excellent tools that enabled the identification of apicomplexan parasites by clarifying their evolutionary relationships.

Abstract

Apicomplexa is a phylum that includes all parasitic protozoa sharing unique ultrastructural features. Haemogregarines are sophisticated apicomplexan blood parasites with an obligatory heteroxenous life cycle and haplohomophasic alternation of generations. Haemogregarines are common blood parasites of fish, amphibians, lizards, snakes, turtles, tortoises, crocodilians, birds, and mammals. Haemogregarine ultrastructure has been so far examined only for stages from the vertebrate host. PCR-based assays and the sequencing of the 18S rRNA gene are helpful methods to further characterize this parasite group. The proper classification for the haemogregarine complex is available with the criteria of generic and unique diagnosis of these parasites.

The genetic diversity of blood parasites within the freshwater turtles Mauremys leprosa and Emys orbicularis in Tunisia reveals coinfection with Haemogregarina spp

Haemogregarina species are apicomplexan blood parasites infecting vertebrates such as fish, lizards, and turtles. Due to the high morphological similarity of the erythrocytic stages infecting host species, it has always been a challenge to identify the true diversity of these parasites. Therefore, taxonomic studies are presently based on the combination of morphological and molecular data. In Tunisia, two species of Haemogregarina have been reported within the freshwater turtle Mauremys leprosa (Geoemydidae) for more than 40 years. Since M. leprosa occurs in the same aquatic environments as Emys orbicularis (Emydidae) in Tunisia, our objectives were to assess parasite diversity and specificity on the basis of both morphological and molecular approaches. The turtles were surveyed and sampled across six aquatic areas of Tunisia. Among the 39 specimens of M. leprosa and seven of E. orbicularis that were trapped and investigated, the presence of haemogregarines was detected in the blood of turtles only at sites where leeches were observed. Three 18S variants were identified, which corresponded to three distinct Haemogregarina species, among which one was identified as Haemogregarina stepanowi. The two other species that were detected are likely new to science. Because we show the occurrence of more than one blood parasite species within a single host specimen, our study provides the first report of coinfection with molecularly distinct Haemogregarina spp.

Haemogregarina daviesensis sp. nov. (Apicomplexa: Haemogregarinidae) from South American lungfish Lepidosiren paradoxa (Sarcopterygii: Lepidosirenidae) in the eastern Amazon region

Based on morphology and morphometry of gametocytes in blood and molecular phylogenetic analysis, we described a new species of hemoparasite from the genus Haemogregarina isolated from Lepidosiren paradoxa in the eastern Amazon region. Haemogregarina daviesensis sp. nov. is characterized by monomorphic gametocytes of varying maturity stage and their dimensions were 16 ± 0.12 μm (range 13-18) in length and 6 ± 0.97 μm (range 5-8) in width. The morphological and morphometric data were not identical with other haemogregarine species from fish. All specimens of L. paradoxa analyzed were infected by H. daviesensis sp. nov. and the parasitemia level was moderate (1-28/2000 blood erythrocytes). Two sequences were obtained from L. paradoxa, and these constituted a monophyletic sister clade to the Haemogregarina species. In addition, H. daviesensis sp. nov. detected here grouped with Haemogregarina sp. sequences isolated from chelonian Macrochelys temminckii, with 99% bootstrap support. This study provides the first data on the molecular phylogeny of an intraerythrocytic haemogregarine of freshwater fish and highlights the importance of obtaining additional information on aspects of the general biology of these hemoparasites in fish populations, in order to achieve correct taxonomic classification.