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Marine and freshwater ecosystems are fundamentally different regarding many biotic and abiotic parameters. The physiological adaptations required for an organism to pass the salinity barrier are considerable. Many eukaryotic lineages are restricted to either freshwater or marine environments. Molecular phylogenetic analyses generally demonstrate that freshwater species and marine species segregate into different subclades, indicating that transitions between these two environments occur only rarely in the course of evolution. It is, however, unclear if the transitions between freshwater and environments characterized by highly variable salinities, such as the marine supralittoral zone, are also infrequent. Here, we use testate amoebae within the Euglyphida to assess the phylogenetic interrelationships between marine supralittoral and freshwater taxa. Euglyphid testate amoebae are mainly present in freshwater habitats but also occur in marine supralittoral environments. Accordingly, we generated and analyzed partial SSU rRNA gene sequences from 49 new marine/supralittoral and freshwater Cyphoderiidae sequences, 20 sequences of the Paulinellidae, Trinematidae, Assulinidae, and Euglyphidae families as well as 21 GenBank sequences of unidentified taxa derived from environmental PCR surveys. Both the molecular and morphological data suggest that the diversity of Cyphoderiidae is strongly underestimated. The results of our phylogenetic analyses demonstrated that marine supralittoral and freshwater euglyphid testate amoeba species are segregated into distinct sub- clades, suggesting that transitions between these two habitats occurred only infrequently.

ParaFishControl is coordinated by Spanish National Research Council (CSIC)., Scuticociliatosis is a severe disease in farmed flatfish. However, the causative agent is not always accurately identified. In this study, we identified two isolates of scuticociliates from an outbreak in cultured fine flounder Paralichthys adspersus. Scuticociliate identification was based on morphological data, examination of life stages and the use of molecular approaches. The isolates were compared with a strain of Philasterides dicentrachi from turbot Scophthalmus maximus and with a strain deposited in the American Type Culture Collection as Miamiensis avidus ATCC® 50180™. The use of morphological, biological and molecular methods enabled us to identify the isolates from the fine flouder as P. dicentrarchi. Comparison of P. dicentrachi isolates and M. avidus revealed some differences in the buccal apparatus. Unlike P. dicentrarchi, M. avidus has a life cycle with three forms: macrostomes (capable of feeding on P. dicentrarchi), microstomes and tomites. Additionally, we found differences in the 18S rRNA and α- and β-tubulin gene sequences, indicating that P. dicentrarchi and M. avidus are different species. We therefore reject the synonymy/conspecificity of the two taxa previously suggested. Finally, we suggest that a combination of morphological, biological, molecular (by multigene analysis) and serological techniques could improve the identification of scuticociliates parasites in fish., This study was financially supported by grant AGL2014-57125-R from the Ministerio de Economía y Competitividad (Spain), by grant GPC2014/069 from the Xunta de Galicia (Spain) and by PARAFISHCONTROL project. This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 634429.

Sequence analyses of six isolates from Southeast Asia supports dividing species into types, Complete DNA sequences of the small subunit ribosomal RNA (SSUrRNA) gene and partial sequences of three other loci were obtained from three variant-type and three classic-type Plasmodium ovale isolates from Southeast Asia and compared with GenBank-available data. Three different SSUrRNA sequences (Pov 1–3) were found in each variant-type isolate, and two different SSUrRNA sequences (Poc 1–2) in each classic-type isolate. Pov 1–3 were closer to sequences previously found in the Cameroon and MAL/MAI isolates, whereas Poc 1–2 were closer to sequences previously found in two clones of the Nigerian I/CDC strain. The 3´ half of Pov 1–3 was identical to the partial sequence of the SSUrRNA gene from the London School (LS) strain. Results support grouping P. ovale into two groups, the classic type (including the Nigerian I/CDC strain) and the variant type (Cameroon, MAL/MAI, and LS isolates).

To date only five partial and two complete SSU rRNA gene sequences are available for the lobose testate amoebae (Arcellinida). Consequently, the phylogenetic relationships among taxa and the definition of species are still largely dependant on morphological characters of uncertain value, which causes confusion in the phylogeny, taxonomy and the debate on cosmopolitanism of free-living protists. Here we present a SSU rRNA-based phylogeny of the Hyalospheniidae including the most common species. Similar to the filose testate amoebae of the order Euglyphida the most basal clades have a terminal aperture; the ventral position of the pseudostome appears to be a derived character. Family Hyalospheniidae appears paraphyletic and is separated into three clades: (1) Heleopera sphagni, (2) Heleopera rosea and Argynnia dentistoma and (3) the rest of the species from genera Apodera, Hyalosphenia, Porosia and Nebela. Our data support the validity of morphological characters used to define species among the Hyalospheniidae and even suggest that taxa described as varieties may deserve the rank of species (e.g. N. penardiana var. minor). Finally our results suggest that the genera Hyalosphenia and Nebela are paraphyletic, and that Porosia bigibbosa branches inside the main Nebela clade.