Novel genotypes of Trypanosoma binneyi from wild platypuses (Ornithorhynchus anatinus) and identification of a leech as a potential vector

Applying a modified streamlined disease risk analysis framework to a platypus conservation translocation, with special consideration for the conservation of ecto- and endoparasites

Platypuses are the world's most evolutionarily distinct mammal and have several host-specific ecto- and endoparasites. With platypus populations declining, consideration should also be given to preserving these high conservation priority parasites alongside their charismatic host. A disease risk analysis (DRA) was performed for a platypus conservation translocation, using a modified streamlined methodology that incorporated a parasite conservation framework. DRA frameworks rarely consider parasite conservation. Rather, parasites are typically considered myopically in terms of the potential harm they may cause their host. To address this, a previously proposed parasite conservation framework was incorporated into an existing streamlined DRA methodology. Incorporation of the two frameworks was achieved readily, although there is opportunity for further refinement of this process. This DRA is significant as it is the first performed for any monotreme species, and implements the emerging approach of balancing the health and disease risk of the host with parasite conservation.

Novel trypanosomatid species detected in Mongolian pikas (Ochotona pallasi) and their fleas in northwestern China

BACKGROUND

In the family Trypanosomatidae, the genus Trypanosoma contains protozoan parasites that infect a diverse range of hosts, including humans, domestic animals, and wildlife. Wild rodents, as natural reservoir hosts of various pathogens, play an important role in the evolution and emergence of Trypanosomatidae. To date, no reports are available on the trypanosomatid infection of pikas (Lagomorpha: Ochotonidae).

METHODS

In this study, Mongolian pikas and their fleas were sampled at the China-Mongolia border, northwestern China. The samples were analyzed with polymerase chain reaction (PCR) and sequencing for the presence of Trypanosomatidae on the basis of both the 18S ribosomal RNA (18S rRNA) gene and the glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. The morphology of trypomastigotes was also observed in peripheral blood smears by microscopy.

RESULTS

Molecular and phylogenetic analyses revealed a new genotype of the Trypanosoma lewisi clade that was found both in pika blood and flea samples. This genotype, which probably represents a new species, was provisionally designated as "Trypanosoma sp. pika". In addition, a novel genotype belonging to the genus Blechomonas of Trypanosomatidae was detected in fleas. On the basis of its molecular and phylogenetic properties, this genotype was named Blechomonas luni-like, because it was shown to be the closest related to B. luni compared with other flea-associated trypanosomatids.

CONCLUSIONS

To the best of our knowledge, this is the first study to report any trypanosomatid species in Mongolian pikas and their fleas. Further studies are needed to investigate the epidemiology of these protozoan parasites, as well as to evaluate their pathogenicity for humans or domestic animals.

A new species of mammalian trypanosome, Trypanosoma (Megatrypanum) bubalisi sp. nov., found in the freshwater leech Hirudinaria manillensis

Leeches have long been considered potential vectors for the aquatic lineage of trypanosomes, while bloodsucking insects are generally considered as the vectors for the terrestrial lineage of trypanosomes. The freshwater leech, Hirudinaria manillensis, is a widely distributed species in southern China and could potentially act as the vector for trypanosomes. Prior to this study, no trypanosomes had been reported from this leech. However, in this study, leeches were collected from three different places in Guangdong province, China, and a large number of flagellates were isolated and successfully cultured in vitro. Based on morphology, these flagellates looked like a typical trypanosome species. Analysis was carried out on the molecular sequences of the 18S rRNA gene and the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. To our surprise, these flagellates were identified as likely to be a mammalian trypanosome belonging to the clade containing Trypanosoma (Megatrypanum) theileri but they are significantly different from the typical TthI and TthII stocks. Analyses of blood composition indicated that the source of the blood meal in these leeches was from the water buffalo (Bubalus bubalis). To further test if this flagellate from the freshwater leech was indeed a mammalian trypanosome, we transferred the trypanosomes cultured at 27-37 °C and they were able to successfully adapt to this mammalian body temperature, providing further supporting evidence. Due to the significant genetic differences from other related trypanosomes in the subgenus Megatrypanum, we propose that this flagellate, isolated from H. manillensis, is a new species and have named it Trypanosoma bubalisi. Our results indicate that freshwater leeches may be a potential vector of this new mammalian trypanosome.

The neglected diversity: Description and molecular characterisation of Trypanosoma haploblephari Yeld and Smit, 2006 from endemic catsharks (Scyliorhinidae) in South Africa, the first trypanosome sequence data from sharks globally

With over 200 species of sharks reported from South African waters, the potential of discovering new blood parasites is very high. Unfortunately, this remains a poorly explored area of research, particularly in this biogeographical region. To date, only a single trypanosome species, Trypanosoma haploblephari Yeld and Smit, 2006, has been described from elasmobranchs off the coast of South Africa infecting the catsharks Haploblepharus pictus (Müller & Henle) and Haploblepharus edwardsii (Schinz). With only a single trypanosome species described and absence of molecular information, a study was conducted to provide further morphological and molecular information on T. haploblephari, a species considered not to demonstrate any pleomorphism. Thin blood smears were prepared, and blood was collected in molecular-grade ethanol from the caudal vein of two shark species, H. pictus and Poroderma pantherinum (Müller & Henle). Trypanosomes were morphologically described and molecularly characterised based on analysis of fragments of the 18S ribosomal gene. The presence of T. haploblephari in H. pictus was confirmed using the original description based on morphology, type host and locality, which allowed for the molecular characterisation of the species. In addition, this species was found parasitising P. pantherinum, its morphology considerably different in this host species as compared to that in the species of Haploblepharus, demonstrating that T. haploblephari may show extreme pleomorphism. This paper provides both morphological and molecular data for both morphotypes of T. haploblephari, with molecular comparisons to the only two other elasmobranch species of trypanosome for which sequence data is available. To elucidate the relationship of trypanosomes from aquatic hosts in general, more efforts need to be placed on elasmobranchs, as current phylogenetic studies are predominantly focused on trypanosomes infecting freshwater fishes.

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First molecular characterization of trypanosomes in endemic sharks in South Africa.

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Illustration of extreme morphological plasticity in trypanosomes.

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Phylogenetic analysis of marine and freshwater fish trypanosomes.

A new subspecies of Trypanosoma cyclops found in the Australian terrestrial leech Chtonobdella bilineata

Previously, it was suggested that haemadipsid leeches represent an important vector of trypanosomes amongst native animals in Australia. Consequently, Chtonobdella bilineata leeches were investigated for the presence of trypanosome species by polymerase chain reaction (PCR), DNA sequencing and in vitro isolation. Phylogenetic analysis ensued to further define the populations present. PCR targeting the 28S rDNA demonstrated that over 95% of C. bilineata contained trypanosomes; diversity profiling by deep amplicon sequencing of 18S rDNA indicated the presence of four different clusters related to the Trypanosoma (Megatrypanum) theileri. Novy–MacNeal–Nicolle slopes with liquid overlay were used to isolate trypanosomes into culture that proved similar in morphology to Trypanosoma cyclops in that they contained a large numbers of acidocalcisomes. Phylogeny of 18S rDNA/GAPDH/ND5 DNA sequences from primary cultures and subclones showed the trypanosomes were monophyletic, with T. cyclops as a sister group. Blood-meal analysis of leeches showed that leeches primarily contained blood from swamp wallaby (Wallabia bicolour), human (Homo sapiens) or horse (Equus sp.). The leech C. bilineata is a host for at least five lineages of Trypanosoma sp. and these are monophyletic with T. cyclops; we propose Trypanosoma cyclops australiensis as a subspecies of T. cyclops based on genetic similarity and biogeography considerations.

Blood Parasites in Endangered Wildlife-Trypanosomes Discovered During a Survey of Haemoprotozoa from the Tasmanian Devil

The impact of emerging infectious diseases is increasingly recognised as a major threat to wildlife. Wild populations of the endangered Tasmanian devil, Sarcophilus harrisii, are experiencing devastating losses from a novel transmissible cancer, devil facial tumour disease (DFTD); however, despite the rapid decline of this species, there is currently no information on the presence of haemoprotozoan parasites. In the present study, 95 Tasmanian devil blood samples were collected from four populations in Tasmania, Australia, which underwent molecular screening to detect four major groups of haemoprotozoa: (i) trypanosomes, (ii) piroplasms, (iii) Hepatozoon, and (iv) haemosporidia. Sequence results revealed Trypanosoma infections in 32/95 individuals. Trypanosoma copemani was identified in 10 Tasmanian devils from three sites and a second Trypanosoma sp. was identified in 22 individuals that were grouped within the poorly described T. cyclops clade. A single blood sample was positive for Babesia sp., which most closely matched Babesia lohae. No other blood protozoan parasite DNA was detected. This study provides the first insight into haemoprotozoa from the Tasmanian devil and the first identification of Trypanosoma and Babesia in this carnivorous marsupial.

'Hang on a Tick' - Are Ticks Really the Vectors for Australian Trypanosomes?

Trypanosomes are global blood parasites that infect a wide range of vertebrate hosts. Several species of Trypanosoma cause disease in humans and domesticated animals, and the majority are transmitted between hosts by haematophagous invertebrate vectors. Ticks have long been speculated as vectors for Australian trypanosomes. Recent studies using advanced molecular techniques have refocused attention on these arthropods, and whilst they have renewed discussions about Trypanosoma species and their vectors, these reports have simultaneously led to premature conclusions concerning the role of ticks as vectors. Here the controversy surrounding ticks as trypanosome vectors is discussed. We highlight the unanswered questions concerning the role played by ticks in trypanosome transmission and suggest future approaches to resolving these key knowledge gaps.

Shared species of crocodilian trypanosomes carried by tabanid flies in Africa and South America, including the description of a new species from caimans, Trypanosoma kaiowa n. sp

Background

The genus Trypanosoma Gruby, 1843 is constituted by terrestrial and aquatic phylogenetic lineages both harboring understudied trypanosomes from reptiles including an increasing diversity of crocodilian trypanosomes. Trypanosoma clandestinus Teixeira & Camargo, 2016 of the aquatic lineage is transmitted by leeches to caimans. Trypanosoma grayi Novy, 1906 of the terrestrial lineage is transmitted by tsetse flies to crocodiles in Africa, but the vectors of Neotropical caiman trypanosomes nested in this lineage remain unknown.

Results

Our phylogenetic analyses uncovered crocodilian trypanosomes in tabanids from South America and Africa, and trypanosomes other than T. grayi in tsetse flies. All trypanosomes found in tabanids clustered in the crocodilian clade (terrestrial lineage) forming six clades: Grayi (African trypanosomes from crocodiles and tsetse flies); Ralphi (trypanosomes from caimans, African and Brazilian tabanids and tsetse flies); Terena (caimans); Cay03 (caimans and Brazilian tabanids); and two new clades, Tab01 (Brazilian tabanid and tsetse flies) and Kaiowa. The clade Kaiowa comprises Trypanosoma kaiowa n. sp. and trypanosomes from African and Brazilian tabanids, caimans, tsetse flies and the African dwarf crocodile. Trypanosoma kaiowa n. sp. heavily colonises tabanid guts and differs remarkably in morphology from other caiman trypanosomes. This species multiplied predominantly as promastigotes on log-phase cultures showing scarce epimastigotes and exhibited very long flagellates in old cultures. Analyses of growth behavior revealed that insect cells allow the intracellular development of Trypanosoma kaiowa n. sp.

Conclusions

Prior to this description of Trypanosoma kaiowa n. sp., no crocodilian trypanosome parasitic in tabanid flies had been cultured, morphologically examined by light, scanning and transmission microscopy, and phylogenetically compared with other crocodilian trypanosomes. Additionally, trypanosomes thought to be restricted to caimans were identified in Brazilian and African tabanids, tsetse flies and the dwarf crocodile. Similar repertoires of trypanosomes found in South American caimans, African crocodiles and tabanids from both continents support the recent diversification of these transcontinental trypanosomes. Our findings are consistent with trypanosome host-switching likely mediated by tabanid flies between caimans and transoceanic migrant crocodiles co-inhabiting South American wetlands at the Miocene.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3463-2) contains supplementary material, which is available to authorized users.

Haematozoa of wild catfishes in northern Australia

Very little is known about the diversity, prevalence, or pathogenicity of haematozoa in Australian freshwater fishes. Blood smears from 189 native catfishes, of six different species, from northern Australia were examined for haematozoa. Haematozoan infections were observed only in fishes from Queensland, at an overall prevalence of 0.191 (95% CI = 0.134-0.265). Intraerythrocytic haemogregarines were present in Neoarius graeffei from the Brisbane River at a prevalence of 0.35 (0.181-0.567). Trypanosomes were present in Tandanus species from four rivers, at prevalences ranging from 0.111 (0.020-0.330) to 1 (0.635-1), and in N. graeffei from one river in Queensland, at a prevalence of 0.063 (0.003-0.305). The haematozoans observed appeared to have little impact on their hosts. Tandanus spp. were significantly more likely to be infected with trypanosomes, suggesting a high parasite-host specificity. This is the first widespread survey of wild Australian freshwater catfishes for haematozoa, resulting in the first report of haemogregarines from Australian freshwater fish, and the first report of trypanosomes from Neoarius graeffei and Tandanus tropicanus.

Wildlife parasitology in Australia: past, present and future

Wildlife parasitology is a highly diverse area of research encompassing many fields including taxonomy, ecology, pathology and epidemiology, and with participants from extremely disparate scientific fields. In addition, the organisms studied are highly dissimilar, ranging from platyhelminths, nematodes and acanthocephalans to insects, arachnids, crustaceans and protists. This review of the parasites of wildlife in Australia highlights the advances made to date, focussing on the work, interests and major findings of researchers over the years and identifies current significant gaps that exist in our understanding. The review is divided into three sections covering protist, helminth and arthropod parasites. The challenge to document the diversity of parasites in Australia continues at a traditional level but the advent of molecular methods has heightened the significance of this issue. Modern methods are providing an avenue for major advances in documenting and restructuring the phylogeny of protistan parasites in particular, while facilitating the recognition of species complexes in helminth taxa previously defined by traditional morphological methods. The life cycles, ecology and general biology of most parasites of wildlife in Australia are extremely poorly understood. While the phylogenetic origins of the Australian vertebrate fauna are complex, so too are the likely origins of their parasites, which do not necessarily mirror those of their hosts. This aspect of parasite evolution is a continuing area for research in the case of helminths, but remains to be addressed for many other parasitic groups.

A novel Ehrlichia species in blood and Ixodes ornithorhynchi ticks from platypuses (Ornithorhynchus anatinus) in Queensland and Tasmania, Australia

Worldwide, Ehrlichia spp. are emerging infectious organisms of domestic animals and people, however, most Ehrlichia spp. naturally infect wildlife reservoirs causing mainly asymptomatic infections. Australian ecosystems have been under-explored for these potentially pathogenic organisms, and recent studies have identified a range of novel Ehrlichia, and their sister genera, Anaplasma and 'Candidatus Neoehrlichia' species, from native Australian ticks. We used bacterial 16S rRNA (16S) next-generation sequencing and genus-specific PCR to profile the bacterial communities in platypus (Ornithorhynchus anatinus) blood samples and platypus ticks (Ixodes ornithorhynchi), and identified a high prevalence of Ehrlichia sequences. We also observed Ehrlichia-like intra-neutrophilic inclusions (morulae) in PCR-positive stained platypus blood films that were consistent in morphology with other Ehrlichia spp. Bayesian phylogenetic analysis of 16S (1343 bp), gltA (1004 bp), and groEL (1074 bp) gene sequences group the platypus Ehrlichia with 'Candidatus Ehrlichia khabarensis' from far-eastern Russia, and demonstrate that the platypus Ehrlichia is clearly distinct from all other Ehrlichia spp. Enough genetic divergence exists to delineate this platypus Ehrlichia as a separate species that we propose to designate 'Candidatus Ehrlichia ornithorhynchi'. There is no evidence that 'Candidatus Ehrlichia ornithorhynchi' causes disease in wild platypuses, however, the organism does seem to be widespread in Australia, being found in both Queensland and Tasmania. 'Candidatus Ehrlichia ornithorhynchi' is the second native Australian Ehrlichia described and adds to the rapidly growing diversity of recently described native Australian tick-borne bacteria.

New Trypanosoma species, Trypanosoma gennarii sp. nov., from South American marsupial in Brazilian Cerrado

Hundreds of trypanosome species have been described in all mammalian orders, on every continent, including with mixed infections. Trypanosomes circulate in the form of sylvatic enzootic infections transmitted by blood-sucking insects that are associated with the host mammals. Small wild mammals were caught in a fragment of Cerrado terrain on an island in the hydroelectric reservoir of Três Marias, in the central region of the state of Minas Gerais, using pitfall and Sherman traps with different means of attraction. DNA samples from these mammals were subjected to the conventional polymerase chain reaction (PCR) for the full-length genes SSU rDNA and gGAPDH. A total of 232 animals of the orders Didelphimorphia, Rodentia, Chiroptera and Cingulata were caught (total of 17 species). There were also four species of marsupials: Monodelphis domestica, Didelphis albiventris, Gralicinanus agilis and Micoureus paraguaianus. Among these, there were eight positive individuals of Monodelphis domestica. However, nine cultures were established, because one of them was parasitized by two species of trypanosomes: Trypanosoma cruzi and a new trypanosome species. The new species have a large epimastigote forms, and with a well-developed undulating membrane in trypomastigote forms. The new species Trypanosoma gennarii was described in Monodelphis domestica.

Trypanosomiasis in an Australian little red flying fox (Pteropus scapulatus)

Case report

An adult female Australian little red flying fox (Pteropus scapulatus) presented with icterus and anaemia. Examination of a blood smear revealed numerous trypanosomes 20.4–30.8 µm long with tapered ends. Necropsy and histological findings were consistent with trypanosome infection of lymphoid tissue and intravascular haemolysis. Sequence and phylogenetic analysis demonstrated this trypanosome species to be genetically distinct and most similar to Trypanosoma minasense and Trypanosoma rangeli (with a genetic distance of 1% at the 18S rRNA locus for both).

Conclusion

To the authors’ knowledge this is the first report of a trypanosome infection associated with clinical disease in bats.

Haemoprotozoa: Making biological sense of molecular phylogenies

A range of protistan parasites occur in the blood of vertebrates and are transmitted by haematophagous invertebrate vectors. Some 48 genera are recognized in bood primarily on the basis of parasite morphology and host specificity; including extracellular kinetoplastids (trypanosomatids) and intracellular apicomplexa (haemogregarines, haemococcidia, haemosporidia and piroplasms). Gene sequences are available for a growing number of species and molecular phylogenies often link parasite and host or vector evolution. This review endeavours to reconcile molecular clades with biological characters. Four major trypanosomatid clades have been associated with site of development in the vector: salivarian or stercorarian for Trypanosoma, and supra- or peri-pylorian for Leishmania. Four haemogregarine clades have been associated with acarine vectors (Hepatozoon A and B, Karyolysus, Hemolivia) and another two with leeches (Dactylosoma, Haemogregarina sensu stricto). Two haemococcidian clades (Lankesterella, Schellackia) using leeches and mosquitoes (as paratenic hosts!) were paraphyletic with monoxenous enteric coccidia. Two major haemosporidian clades have been associated with mosquito vectors (Plasmodium from mammals, Plasmodium from birds and lizards), two with midges (Hepatocystis from bats, Parahaemoproteus from birds) and two with louse-flies and black-flies (Haemoproteus and Leucocytozoon from birds). Three major piroplasm clades were recognized: one associated with transovarian transmission in ticks (Babesia sensu stricto); one with pre-erythrocytic schizogony in vertebrates (Theileria/Cytauxzoon); and one with neither (Babesia sensu lato). Broad comparative studies with allied groups suggest that trypanosomatids and haemogregarines evolved first in aquatic and then terrestrial environments, as evidenced by extant lineages in invertebrates and their radiation in vertebrates. In contrast, haemosporidia and haemococcidia are thought to have evolved first in vertebrates from proto-coccidia and then incorporated invertebrate vectors. Piroplasms are thought to have evolved in ticks and diversified into mammals. More molecular studies are required on more parasite taxa to refine current thought, but ultimately transmission studies are mandated to determine the vectors for many haemoprotozoa.

INVESTIGATION INTO INDIVIDUAL HEALTH AND EXPOSURE TO INFECTIOUS AGENTS OF PLATYPUSES (ORNITHORHYNCHUS ANATINUS) IN TWO RIVER CATCHMENTS IN NORTHWEST TASMANIA

Changes in the health of individuals within wildlife populations can be a cause or effect of population declines in wildlife species. Aspects of individual platypus ( Ornithorhynchus anatinus ) health have been reported. However, holistic studies investigating potential synergistic effects of both pathogens and environmental factors are needed to expand understanding of platypus individual health. We collected baseline data on the health of platypuses in two Tasmanian river catchments (including evidence of the potentially fatal fungal disease mucormycosis) and on individual, demographic, and geographic patterns associated with health data results. We examined 130 wild platypuses from the Inglis River Catchment and 24 platypuses from the Seabrook Creek Catchment in northwest Tasmania between 29 August 2011 and 31 August 2013. More than 90% of captured platypuses were infected with ticks, Theileria spp., and trypanosomes. Evidence of exposure to other infections, including Salmonella spp., Leptospira spp., and intestinal parasites, was low (<10%). Three platypuses had single fungal granulomas in the webbing of a forefoot, but no evidence of mucormycosis was found in any of the study animals. Possible subclinical hepatopathies or cholangiohepatopathies were found in six platypuses. Exposure to infectious agents did not cluster geographically, demographically, or in individuals, and there was minimal evidence of morbidity resulting from infection. This study has provided important baseline data for monitoring the effects of threatening processes, including mucormycosis, on the health of infected populations.

Host-Parasite Relationships and Life Histories of Trypanosomes in Australia

Trypanosomes constitute a group of flagellate protozoan parasites responsible for a number of important, yet neglected, diseases in both humans and livestock. The most significantly studied include the causative agents of African sleeping sickness (Trypanosoma brucei) and Chagas disease (Trypanosoma cruzi) in humans. Much of our knowledge about trypanosome host-parasite relationships and life histories has come from these two human pathogens. Recent investigations into the diversity and life histories of wildlife trypanosomes in Australia highlight that there exists a great degree of biological and behavioural variation within and between trypanosomes. In addition, the genetic relationships between some Australian trypanosomes show that they are unexpectedly more closely related to species outside Australia than within it. These findings have led to a growing focus on the importance of understanding parasites occurring naturally in wildlife to (1) better document parasite biodiversity, (2) determine evolutionary relationships and degree of host specificity, (3) understand host-parasite interactions and the role of parasites in the natural ecosystem and (4) identify biosecurity issues of emerging disease in both wildlife and human populations. Here we review what is known about the diversity, life histories, host-parasite interactions and evolutionary relationships of trypanosomes in Australian wildlife. In this context, we focus upon the genetic proximity of key Australian species to the pathogenic T. cruzi and discuss similarities in their biology and behaviour that present a potential risk of human disease transmission by Australian vectors and wildlife.

Genetic diversity of Trypanosoma cruzi in bats, and multilocus phylogenetic and phylogeographical analyses supporting Tcbat as an independent DTU (discrete typing unit)

Trypanosoma cruzi is a complex of phenotypically and genetically diverse isolates distributed in six discrete typing units (DTUs) designated as TcI-TcVI. Five years ago, T. cruzi isolates from Brazilian bats showing unique patterns of traditional ribosomal and spliced leader PCRs not clustering into any of the six DTUs were designated as the Tcbat genotype. In the present study, phylogenies inferred using SSU rRNA (small subunit of ribosomal rRNA), gGAPDH (glycosomal glyceraldehyde 3-phosphate dehydrogenase) and Cytb (cytochrome b) genes strongly supported Tcbat as a monophyletic lineage prevalent in Brazil, Panama and Colombia. Providing strong support for Tcbat, sequences from 37 of 47 nuclear and 12 mitochondrial genes (retrieved from a draft genome of Tcbat) and reference strains of all DTUs available in databanks corroborated Tcbat as an independent DTU. Consistent with previous studies, multilocus analysis of most nuclear genes corroborated the evolution of T. cruzi from bat trypanosomes its divergence into two main phylogenetic lineages: the basal TcII; and the lineage clustering TcIV, the clade comprising TcIII and the sister groups TcI-Tcbat. Most likely, the common ancestor of Tcbat and TcI was a bat trypanosome. However, the results of the present analysis did not support Tcbat as the ancestor of all DTUs. Despite the insights provided by reports of TcIII, TcIV and TcII in bats, including Amazonian bats harbouring TcII, further studies are necessary to understand the roles played by bats in the diversification of all DTUs. We also demonstrated that in addition to value as molecular markers for DTU assignment, Cytb, ITS rDNA and the spliced leader (SL) polymorphic sequences suggest spatially structured populations of Tcbat. Phylogenetic and phylogeographical analyses, multiple molecular markers specific to Tcbat, and the degrees of sequence divergence between Tcbat and the accepted DTUs strongly support the definitive classification of Tcbat as a new DTU.

First Molecular Characterization of Theileria ornithorhynchi Mackerras, 1959: yet Another Challenge to the Systematics of the Piroplasms

Piroplasms, tick-transmitted Apicomplexa of the genera Theileria, Babesia and Cytauxzoon, are blood-borne parasites of clinical and veterinary importance. The order Piroplasmida shows a puzzling systematics characterized by multiple clades, soft polytomies and paraphyletic/polyphyletic genera. In the present study, screening of platypuses (Ornithorhynchus anatinus), was performed to infer the parasite molecular phylogeny. DNA was extracted from blood, ectoparasites and tick eggs and the 18S rRNA- hsp70-genes were used for the phylogenetic reconstructions. Microscopic analyses detected pleomorphic intra-erythrocytic organisms and tetrads consistent with previous descriptions of Theileria ornithorhynchi Mackerras, 1959, but observation of possible schizonts could not be confirmed. DNA sequences obtained from blood and ticks allowed resolving the systematics of the first piroplasm infecting a monotreme host. Molecularly, T. ornithorhynchi formed a novel monophyletic group, basal to most known piroplasms' clades. The ancestral position of this clade, isolated from an ancient lineage of mammalian host appears particularly fascinating. The present paper discusses the inadequacies of the current molecular systematics for the Piroplasmida and the consequences of incomplete sampling, morphology-based classification and ambiguous microscopic identifications. Likely when the current sampling bias is rectified and more sequence data is made available, the phylogenetic position of T. ornithorhynchi will be further contextualized without ambiguity.

Field and experimental evidence of a new caiman trypanosome species closely phylogenetically related to fish trypanosomes and transmitted by leeches

Trypanosoma terena and Trypanosoma ralphi are known species of the South American crocodilians Caiman crocodilus, Caiman yacare and Melanosuchus niger and are phylogenetically related to the tsetse-transmitted Trypanosoma grayi of the African Crocodylus niloticus. These trypanosomes form the Crocodilian clade of the terrestrial clade of the genus Trypanosoma. A PCR-survey for trypanosomes in caiman blood samples and in leeches taken from caimans revealed unknown trypanosome diversity and frequent mixed infections. Phylogenies based on SSU (small subunit) of rRNA and gGAPDH (glycosomal Glyceraldehyde Phosphate Dehydrogenase) gene sequences revealed a new trypanosome species clustering with T. terena and T. ralphi in the crocodilian clade and an additional new species nesting in the distant Aquatic clade of trypanosomes, which is herein named Trypanosoma clandestinus n. sp. This new species was found in Caiman yacare, Caiman crocodilus and M. niger from the Pantanal and Amazonian biomes in Brazil. Large numbers of dividing epimastigotes and unique thin and long trypomastigotes were found in the guts of leeches (Haementeria sp.) removed from the mouths of caimans. The trypanosomes recovered from the leeches had sequences identical to those of T. clandestinus of caiman blood samples. Experimental infestation of young caimans (Caiman yacare) with infected leeches resulted in long-lasting T. clandestinus infections that permitted us to delineate its life cycle. In contrast to T. terena, T. ralphi and T. grayi, which are detectable by hemoculturing, microscopy and standard PCR of caiman blood, T. clandestinus passes undetected by these methods due to very low parasitemia and could be detected solely by the more sensitive nested PCR method. T. clandestinus n. sp. is the first crocodilian trypanosome known to be transmitted by leeches and positioned in the aquatic clade closest to fish trypanosomes. Our data show that caimans can host trypanosomes of the aquatic or terrestrial clade, sometimes simultaneously.

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Species richness and geographical range of caiman trypanosomes.

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Trypanosoma clandestinus n. sp. is transmitted by leeches.

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T. clandestinus nests in the Aquatic clade closest to fish trypanosomes.

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Caimans were infected by the bite of leeches carrying T. clandestinus.

Phylogeny and Morphological Variability of Trypanosomes from African Pelomedusid Turtles with Redescription of Trypanosoma mocambicum Pienaar, 1962

Little is known about host specificity, genetic diversity and phylogenetic relationships of African turtle trypanosomes. Using PCR targeting the SSU rRNA gene, we detected trypanosomes in 24 of 134 (17.9%) wild caught African pelomedusid turtles: Pelusios upembae (n=14), P. bechuanicus (n=1), P. rhodesianus (n=3) and P. subniger (n=6). Mixed infection of Trypanosoma species was confirmed by PCR in three specimens of P. upembae, and in one specimen each of P. bechuanicus, P. rhodesianus, and P. subniger. Microscopic examination of stained blood smears revealed two distinct forms (broad and slender) of trypomastigotes. The broad form coincided in morphology with T. mocambicumPienaar, 1962. Accordingly, we have designated this form as the neotype of T. mocambicum. In phylogenetic analysis of the SSU rRNA gene, all the new turtle trypanosome sequences grouped in a single clade within the strongly supported "aquatic" clade of Trypanosoma species. The turtle trypanosome clade was further subdivided into two subclades, which did not correlate with host turtle species or trypanosome morphology. This study provides the first sequence data of Trypanosoma species isolated from freshwater turtles from tropical Africa and extends knowledge on diversity of trypanosomes in the Afrotropical zoogeographical realm.