Louse flies (Hippoboscidae) are permanent ectoparasites of birds and mammals. They have a cosmopolitan distribution with more than 200 described species. The aim of this study was to reveal host–vector–parasite associations between louse flies, birds, and trypanosomes. A total of 567 louse fly specimens belonging to 7 species were collected from birds at several localities in Czechia, including the rare species Ornithophila metallica and Ornithoica turdi. There was a significant difference in the occurrence of Ornithomya avicularia and Ornithomya fringillina on bird hosts according to their migratory status, O. fringillina being found more frequently on long-distance migrants. Trypanosomes were found in four species, namely, Ornithomya avicularia, O. fringillina, O. biloba, and Ornithoica turdi; the later three species are identified in this paper as natural trypanosome vectors for the first time. The prevalence of trypanosomes ranged between 5 and 19%, the highest being in O. biloba and the lowest being in O. fringillina. Phylogenetic analysis of the SSU rRNA gene revealed that a vast majority of trypanosomes from hippoboscids belong to the avian T. corvi/culicavium group B. Four new lineages were revealed in group B, with louse flies being probable vectors for some of these trypanosome lineages. We also confirmed the transcontinental distribution of several trypanosome lineages. Our results show that hippoboscids of several genera are probable vectors of avian trypanosomes.

Avian trypanosomes are cosmopolitan and common protozoan parasites of birds; nevertheless, knowledge of their life cycles and vectors remains incomplete. Mosquitoes have been confirmed as vectors of Trypanosoma culicavium and suggested as vectors of T. thomasbancrofti; however, transmission has been experimentally confirmed only for the former species. This study aims to confirm the experimental transmission of T. thomasbancrofti to birds and its localization in vectors. Culex pipiens were fed on blood using four strains of T. thomasbancrofti, isolated from vectors and avian hosts; all strains established infections, and three of them were able to develop high infection rates in mosquitoes. The infection rate of the culicine isolates was 5–28% for CUL15 and 48–81% for CUL98, 67–92% for isolate OF19 from hippoboscid fly, while the avian isolate PAS343 ranged between 48% and 92%, and heavy infections were detected in 90% of positive females. Contrary to T. culicavium, trypanosomes were localized in the hindgut, where they formed rosettes with the occurrence of free epimastigotes in the hindgut and midgut during late infections. Parasites occurred in urine droplets produced during mosquito prediuresis. Transmission to birds was achieved by the ingestion of mosquito guts containing trypanosomes and via the conjunctiva. Bird infection was proven by blood cultivation and xenodiagnosis; mature infections were present in the dissected guts of 24–26% of mosquitoes fed on infected birds. The prevalence of T. thomasbancrofti in vectors in nature and in avian populations is discussed in this paper. This study confirms the vectorial capacity of culicine mosquitoes for T. thomasbancrofti, a trypanosome related to T. avium, and suggests that prediuresis might be an effective mode of trypanosome transmission.

Background: Myxozoans are ancient cnidarian parasites with highly derived genomes characterized by an extremely accelerated rate of nucleotide substitution, abundant orphan and lineage-specific genes without further characterization. Genome data are limited to two out of the four main evolutionary lineages, assemblies are highly fragmented and often show significant levels of host contamination. Results: We present a near chromosome-scale myxozoan genome, based on Oxford Nanopore-reads of Sphaerospora molnari, a member of the previously uncharacterized group of blood-feeding myxozoans, thereby addressing a key gap in the subphylum’s phylogeny. The haploid genome assembly spans 40.17 Mb in 40 contigs, harbors 14,957 genes and shows the smallest mitogenome of myxozoans (14,015 bp). Gene gain/gene loss analyses showed that myxozoans have small ancestral gene repertoires and show highly lineage-specific genome compositions. Using comparative analyses focusing on identifying unique but diversified gene compartments in S. molnari, we discovered taxonomically restricted protist genes related to red blood cell attachment ( Plasmodium ETRAMPs) and surface protein variation ( Plasmodium variant surface antigen families RIFIN and STEVOR, as well as Metamonada variant-specific surface proteins, VSPs), raising questions about their origins and evolution. A genomic trait shared between several myxozoans is the significant expansion of DNA transposable elements belonging to the mutator-like elements (MULEs), and while the simple copy-paste mechanism of these transposases may suggest frequent uncontrolled mutation, we demonstrate domestication of MULEs into transcription factors. Analyses of the gene fragments of chimeric MULEs (pack-MULES) of S. molnari show that these coincide with highly diversified gene groups in this lineage, including alien genes, suggesting MULEs as a driving force for gene evolution in myxozoans. Conclusions: Parasitic lifestyle shifts drive exceptionally rapid genome evolution in myxozoans, primarily through nonadaptive mutation and gene transfer via MULEs, with adaptive refinement through MULE domestication and selection. In S. molnari , these processes underpin unique erythrocyte exploitation and immune evasion strategies essential for survival in the hosts’ bloodstream.

Background: Rhizaria is a eukaryotic supergroup including many amoeboid protists. Despite harboring a large diversity and many ecologically important species, the genomes belonging to this supergroup remain poorly explored. With only a handful available genome sequences, most of low contiguity, little is known about overall architecture, characteristics, and evolution of rhizarian genomes. Results: We provide a highly contiguous genome assembly of an undescribed marine rhizarian amoeba formerly known as M6MM. The assembly revealed a small (27 Mb; 8704 genes) and compact genome (84% genes, 10% repeats, 6% intergenic regions), and was almost fully captured in six contigs confirmed cytologically to represent chromosomes. The genome contains a very large amount of simple-sequence repeats (SSRs), particularly of the AC:GT dinucleotide class (206 loci/Mb), in total covering almost 2% of the assembly. We also obtained the complete mitochondrial genome, which is reduced and devoid of ribosomal protein genes similarly to some other rhizarians. Some of these “missing” mitochondrial-encoded genes are found in the nuclear genome and are predicted to be targeted to the mitochondrion. In our 18S rDNA phylogenetic analysis, M6MM loosely groups with environmental sequences and the amoeboflagellate Viscidocauda repens . However, this amoeba is phylogenetically distant from any described species and expresses a unique pseudopodial morphology, prompting us to erect the novel genus and species Lemnamoeba sinaloensis gen. nov. et. sp. nov. Environmental data show that L. sinaloensis has a wide marine distribution and can mostly be found between the surface and 100 m depths. Conclusion: This study adds another genus to the hitherto taxonomically poor Apofilosa, provides one of the highest-quality rhizarian genome assemblies to date, and reveals an abundance of SSRs in the genome, highlighting the complexity of eukaryotic genomes in underexplored parts of the tree of life.