A new species of the genus Plagiorhynchus Lühe, 1911 from the intestine of the long-billed curlew (Numenius americanus) from northern Mexico is described. Plagiorhynchus (Plagiorhynchus) aznari n. sp. is morphologically distinguished from other congeneric species from the Americas by having a trunk expanded anteriorly and a cylindrical proboscis, armed with 19 longitudinal rows of hooks, with 14–15 hooks each row. Nearly complete sequences of the small subunit and large subunit of the nuclear ribosomal DNA of the new species were determined and compared with available sequences from GenBank. Phylogenetic analyses inferred from the two molecular markers consistently showed that P. (Plagiorhynchus) aznari n. sp. is closely related to P. (Plagiorhynchus) allisonae, and this clade is sister to a clade formed by P. (Prosthorhynchus) transversus and P. (Prosthorhynchus) cylindraceus from Plagiorhynchidae. The new species represents the second record of the genus in Mexico and the fourth species in the Americas. The phylogenetic relationships among the members of the order Polymorphida in this study provide significant insights into the evolution of ecological associations between parasites and their definitive hosts. Our analyses suggest that the colonization of marine mammals, fish-eating birds and waterfowl in Polymorphidae might have occurred independently, from a common ancestor of Centrorhynchidae and Plagiorhynchidae that colonized terrestrial birds and mammals.

The Myxozoa demonstrate extensive morphological simplification and miniaturization relative to their free-living cnidarian ancestors. This is particularly pronounced in the highly derived myxosporeans, which develop as plasmodia and pseudoplasmodia. To date, motility in these stages has been linked with membrane deformation (e.g. as pseudopodia and mobile folds). Here we illustrate a motile, elongate plasmodium that undergoes coordinated undulatory locomotion, revealing remarkable convergence to a functional worm at the cellular level. Ultrastructural and confocal analyses of these plasmodia identify a highly differentiated external layer containing an actin-rich network, long tubular mitochondria, abundant microtubules, a secreted glycocalyx layer, and an internal region where sporogony occurs and which contains homogeneously distributed granular/fibrillar material. We consider how some of these features may support motility. We also describe the species based on spore morphology and SSU rDNA sequence data, undertake molecular phylogenetic analysis to place it within an early-diverging clade of the ceratomyxids, and evaluate the resultant implications for classification (validity of the genus Meglitschia) and for inferring early host environments (freshwater) of ceratomyxids.

Our survey of marine fish from South Africa and Indonesia revealed the presence of two new myxosporean species of the genus Sphaeromyxa for which we provide morphological and sequence data. Sphaeromyxa clini n. sp. detected in three Clinus spp. and Muraenoclinus dorsalis from South Africa is morphologically similar to Sphaeromyxa noblei previously described from Heteroclinus whiteleggii from Australia and to several other sphaeromyxids with arcuate spores and rounded ends. This similarity is reflected by phylogenetic positioning of S. clini n. sp. which clusters within the ‘incurvata’ group of the Sphaeromyxa clade. It differs from morphologically similar species by spore and polar capsule dimensions, host specificity and geographic distribution. Sphaeromyxa limocapitis n. sp., described from Gephyroberyx darwinii from Java, is morphologically similar to sphaeromyxids with straight spores and to marine Myxidium species with spindle-shaped spores but differs from them by spore and polar capsule dimensions, host specificity and geographic distribution. S. limocapitis n. sp. represents a separate lineage of the Sphaeromyxa clade and appears to be a missing link in the evolution of sphaeromyxids.

Phylogenetic analyses of SSU rDNA sequences have previously revealed the existence of 2 Ichthyobodo species able to infect Atlantic salmon (Salmo salar L.). Ichthyobodo necator sensu stricto (s.s.) is assumed to be a freshwater parasite, while a genetically distinct but undescribed species, Ichthyobodo sp. II sensu Todal et al. (2004) have been detected on Atlantic salmon in both fresh- and seawater. In the present study a morphological description of Ichthyobodo sp. II from the gills of salmon reared in fresh-, brackish- and seawater is presented, using both light- and electron microscopy. Comparative morphometry show that Ichthyobodo sp. II from both freshwater and seawater displays a different cell shape, and is significantly smaller than I. necator s.s. Also, ultrastructural characteristics distinguish these two species, notably differences in the attachment region and the presence of spine-like surface projections in Ichthyobodo sp. II. Based on both unique SSU rDNA sequences and morphological characteristics, we conclude that Ichthyobodo sp. II. represents a novel species for which we propose the name Ichthyobodo salmonis sp. n.

This work reports a new type of actinospore, Unicapsulactinomyxon, which exhibits a unique morphological characteristic in that it has a single and large polar capsule (9·3×4·1 μm) (which possesses a longitudinally-folded polar filament) instead of the 3 polar capsules previously described for actinosporeans. The spore has a binucleated sporoplasm and 3 valves, each of which forms a long process. The spore has a total length of 241·3 μm. This parasite develops in groups of 8 inside pansporocysts in the coelomic cavity of the polychaete host. Molecular investigations on the SSU rDNA show that the new actinospore type is most closely related to Enteromyxum species (81–84% similarity). A survey of actinospore infections of the marine polychaete Diopatra neapolitana in 2007 and 2009, in the Aveiro Estuary (Portugal), showed an annual prevalence of 1·0% and 0·3%, respectively.

An amendment of the family Sinuolineidae (Myxosporea) is proposed in order to include a newly described genus Latyspora n. gen. The type species Latyspora scomberomori n. gen. n. sp. is a coelozoic parasite in the kidney tubules of Scomberomorus guttatus. In addition to the morphological and molecular characterization of L. scomberomori n. gen. n. sp., we also present novel SSU rDNA data on Sphaerospora testicularis, a serious parasite of Dicentrarchus labrax. Performed phylogenetic analyses revealed that both species cluster within the marine urinary clade encompassing the representatives with a shared insertion within their V4 SSU rRNA region and grouping according to the shape of their spores’ sutural line and their similar tissue tropism in the host. Sphaerospora testicularis is the closest relative to Parvicapsula minibicornis within the Parvicapsula subclade and L. scomberomori n. gen. n. sp. is the basal species of the Zschokkella subclade. The phylogenetic position of S. testicularis, outwith the basal Sphaerospora sensu stricto clade, and its morphology suggest it being a non-typical Sphaerospora. The sequence data provided on S. testicularis can help in future revisions of the strongly polyphyletic genus Sphaerospora. We recommend re-sequencing of several sphaerosporids as an essential step before such taxonomic changes are accomplished.

Dikerogammarus villosus is an invasive amphipod that recently colonized the main rivers of Central and Western Europe. Two frequent microsporidian parasites were previously detected in this species, but their taxonomic status was unclear. Here we present ultrastructural and molecular data indicating that these two parasites are in fact a single microsporidian species. This parasite shares numerous characteristics of Nosema spp. It forms elongate spores (cucumiform), developing in direct contact with host cell cytoplasm; all developmental stages are diplokaryotic and the life cycle is monomorphic with disporoblastic sporogony. Initially this parasite was described as Nosema dikerogammariOvcharenko and Kurandina 1987. However, phylogenetic analysis based on the complete sequence of SSU rDNA places the parasite outside the genus Nosema and it is therefore ascribed to a new genus Cucumispora. The key features characteristic to this genus are: presence of a very well-developed, umbrella-shape anchoring disk covering the anterior part of polaroplast; arrangement of isofilar polar filament into 6–8 coils convoluted with different angles, voluminous diplokaryon, thin spore wall and relatively small posterior vacuole containing posterosome. The parasite infects most host tissues but mainly muscles. It showed high rates of horizontal trophic transmission and lower rates of vertical transmission.

Unusual tumour-like pathologies caused by mysterious cells termed ‘X-cells’ have been reported from numerous fish groups worldwide. After nearly 100 years of research, the tumour-like growths have recently been shown to be caused by a protozoan parasite. In the present study, histopathology and small subunit ribosomal DNA (SSU rDNA) sequences are used to assess whether the X-cell parasite infecting Atlantic dab Limanda limanda L. is distinct from the X-cell parasite infecting Japanese flounder and goby, and to determine their systematic position within the protists. SSU rDNA from Scottish dab was 89·3% and 86·7% similar to Japanese X-cell sequences from flounder and goby respectively, indicating that the parasite infecting dab in the Atlantic is distinct from the Pacific species. Histological studies revealed significant gill pathology and demonstrated the precise location of the parasites within the gill tissues using specific in situ hybridization probes. Phylogenetic analyses showed that the X-cell parasites from Scotland and Japan form a monophyletic group within the Myzozoa, and are basal alveolates. However, ultrastructure of X-cells from dab fails to confirm this systematic placement.

We characterized 15 Trypanosoma cruzi isolates from bats captured in the Amazon, Central and Southeast Brazilian regions. Phylogenetic relationships among T. cruzi lineages using SSU rDNA, cytochrome b, and Histone H2B genes positioned all Amazonian isolates into T. cruzi I (TCI). However, bat isolates from the other regions, which had been genotyped as T. cruzi II (TC II) by the traditional genotyping method based on mini-exon gene employed in this study, were not nested within any of the previously defined TCII sublineages, constituting a new genotype designated as TCbat. Phylogenetic analyses demonstrated that TCbat indeed belongs to T. cruzi and not to other closely related bat trypanosomes of the subgenus Schizotrypanum, and that although separated by large genetic distances TCbat is closest to lineage TCI. A genotyping method targeting ITS1 rDNA distinguished TCbat from established T. cruzi lineages, and from other Schizotrypanum species. In experimentally infected mice, TCbat lacked virulence and yielded low parasitaemias. Isolates of TCbat presented distinctive morphological features and behaviour in triatomines. To date, TCbat genotype was found only in bats from anthropic environments of Central and Southeast Brazil. Our findings indicate that the complexity of T. cruzi is larger than currently known, and confirmed bats as important reservoirs and potential source of T. cruzi infections to humans.

Using a combination of morphological, life-history and molecular data, we redescribe Sphaerospora ranae (Morelle, 1929) n. comb. (previously Leptotheca ranae) and emend its taxonomic status. Renal infection was recorded in 2 spp. of frogs (out of 5 amphibian spp. examined), Rana dalmatina (proposed type host) and Rana temporaria, suggesting restricted host specifity of S. ranae. We provide a description of sporogonic stages of S. ranae for the first time and suggest possible modes of its developmental cycle. Phylogenetic analysis inferred from the small-subunit ribosomal DNA revealed a close relationship of S. ranae with piscine Sphaerospora elegans (type species of the genus) and Sphaerospora truttae, forming together with distantly related Leptotheca fugu a ‘Sphaerosporid clade’, the basal branch to all myxosporean species. The close relationship of the 3 Sphaerospora spp. is further supported by the presence of 2 areas with extensive nucleotide insertions in the V4 region of the SSU rDNA (absent in L. fugu), morphology and life-history features. We conclude, that the spore morphology of Sphaerospora s.l., is very simple and probably represents a ‘primitive’, basal morphotype retained in most myxosporean lineages. Based on presented data, we propose emendation of the genus Sphaerospora using morpological, life-history and molecular features.

A review of the Giardia duodenalis sequences currently available on the GenBank database was completed to compare the different genotyping loci (small subunit ribosomal DNA, glutamate dehydrogenase, triose-phosphate isomerase and beta giardin) for their ability to discern assemblage and subassemblage groups and infer phylogenetic relationships. In total, 405 Giardia duodenalis sequences were sorted and aligned to examine the substitutions within and between the assemblages – A and B (zoonotic), C and D (dogs), E (livestock), F (cats) and G (rodents). It was found that all of the genes could reproducibly group isolates into their assemblages and that the AI/AII subassemblage groups were robust and identifiable at all loci. However, the assemblage B subgroups were not reproducible at half of the loci (small subunit ribosomal DNA and beta giardin), not due to their conserved nature, but because there was insufficient sequence data of reference isolates available for comparison. It is anticipated that further investigation of these loci may reveal the core subgroups of this medically important and zoonotic assemblage and also those of others. The closer, more recent, phylogenetic relationships amongst the assemblages appear to be resolved; however, more sequence data from the current loci, and possibly new loci, will be required to establish the remaining relationships.

During a study on population genetics of three species of Cladonia using the nuclear ribosomal 18S DNA, two species contained group I intron-like sequences located in positions 788 and 940 with reference to the E. coli 16S rDNA gene. The intron in position 940 was not typical of group I introns and had previously been described only from the Parmeliaceae and Lecanoraceae, but here we report the occurrence of this intron in the Cladoniaceae. The intron in position 788 had characteristics of group I introns and had previously been reported from the Physciaceae. In this paper we provide for the first time a putative RNA fold for the nS788 intron, compare the secondary RNA structure of the Cladonia group I introns (nS788 and nS940) to that of other taxa, and infer a phylogenetic history among 15 members of the Lecanorales based on the evolutionary history of the nS788 group I intron. The RNA fold for nS788 contained two optional hairpins, P2.1 and a potentially newly described hairpin referred to as P5.1. The phylogenetic hypothesis supports the monophyly of the genus Cladonia. It also supports the separation of two large groups in the Physciaceae; the Buellia-group and the Physcia-group.

Trypanosoma (Herpetosoma) grosi, which naturally parasitizes Apodemus spp., can experimentally infect Mongolian jirds (Meriones unguiculatus). Three isolates from A. agrarius, A. peninsulae, and A. speciosus (named SESUJI, HANTO, and AKHA isolates, respectively) of different geographical origin (AKHA from Japan, and the others from Vladivostok), exhibited different durations of parasitaemia in laboratory jirds (2 weeks for HANTO, and 3 weeks for the others). To assess the genetic background of these T. grosi isolates, their small (SSU) and large subunit (LSU) ribosomal RNA genes (rDNA) were sequenced along with those of 2 other Herpetosoma species from squirrels. The SSU rDNA sequences of these 3 species along with available sequences of 3 other Herpetosoma trypanosomes (T. lewisi, T. musculi and T. microti) seemed to reflect well the phylogenetic relationship of their hosts. Three isolates of T. grosi exhibited base changes at 2–6 positions of 2019-base 18S rDNA, at 5–29 positions of 1817/1818-base 28Sα rDNA, or 1–5 positions of 1557–1559-base 28Sβ rDNA, and none was separated from the other 2 isolates by rDNA nucleotide sequences. Since base changes of Herpetosoma trypanosomes at the level of inter- and intra-species might occur frequently in specified rDNA regions, the molecular analysis on these regions of rodent trypanosomes could help species/strain differentiation and systematic revision of Herpetosoma trypanosome species, which must be more abundant than presently known.

Genetic diversity of green algal and cyanobacterial photobionts in Nephroma was examined by using nucleotide sequences of the ribosomal gene cluster. The lichens studied included both bipartite and tripartite species. There was very little variation in green algal-ITS sequences of N. arcticum and N. expallidum. Almost identical sequences were obtained from all thalli analysed and also from two tripartite Peltigera species. On the basis of SSU rDNA data the green algal photobionts of N. arcticum are closely related to the primary photobiont of P. britannica, and also to an endophytic alga of Ginkgo biloba. The SSU rDNA region of lichen-forming cyanobacteria was rather variable. A phylogenetic analysis indicated that the Nostoc specimens formed a monophyletic group and the strains were divided into two main groups. One clade included only cyanobionts of lichens, including those of all bipartite Nephroma species. The second group was genetically more heterogeneous and included mainly cyanobionts of terricolous cyanolichens, including those of both tripartite Nephroma species studied. The distinction between bi- and tripartite Nephroma species is significant as the mycobionts of tripartite species are not monophyletic. It implies that within Nephroma, evolutionary transitions between symbiosis types cannot have been achieved simply via an acquisition or loss of the green algal photobiont. As the Nostoc symbionts of bi- and tripartite species belong to different phylogenetic groups, an evolutionary change in green algal association has required a concurrent change in cyanobiont composition.