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Cercozoa are a highly diverse protist phylum in soils and in the phyllosphere of plants. Many families are still poorly described and the vast majority of species are still unknown. Although testate amoebae are among the better-studied protists, only little quantitative information exists on the morphology, phylogeny and ecology of cercozoan Rhogostomidae. We cultured four different strains of Rhogostoma spp. isolated from Arabidopsis leaves, agricultural soil and rhizosphere soil of Ocimum basilicum and Nicotiana sp. We describe Rhogostoma epiphylla sp. nov. and R. cylindrica sp. nov. and present their morphology, studied their food spectra in food range experiments and obtained two SSU rDNA gene sequences resulting in an updated thecofilosean phylogeny. Short generation times, desiccation resistance and the ability to prey on a wide range of algae and yeasts from the phyllosphere were seen as crucial traits for the phyllosphere colonization by Rhogostoma. In contrast, the soil-dwelling R. cylindrica did not feed on eukaryotes in our experiment., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

The morphology of tests ("shells") representing populations of the small testate amoeba Cyphoderia laevisPenard, 1902 (Cercozoa, Euglyphida) from Canada and Hungary was quantified. Despite often considerable variation the cross-sectional shape of tests, multivariate statistical analysis confirmed the general uniformity of test morphology within populations and between populations at both local (regional, inter- and intra-watershed) scales and over inter-continental scales (Canada and Hungary). Corrections are suggested to recently published misidentifications of C. laevis as Corythionella georgiana Nicholls. The differences between these two taxa are subtle, but significant, and are emphasized here to help preclude similar errors in the future. Schaudinnula nanaBadewitz, 2003 is shown to be a superfluous synonym for Cyphoderia laevis. Cyphoderia truncataSchulze, 1875 has some similarities to C. laevis, but its status remains unresolved. Some preliminary reservations are expressed about the classification of Cyphoderia laevis within the genus Cyphoderia owing mainly to its Corythionella-like scale structure and other characteristics of its test that appear to be outside the "usual" range found in other Cyphoderia species., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Two heterotrophic flagellate strains were isolated from marine sediment samples off eastern Canada and Korea. These new isolates are indistinguishable by light microscopy from the unclassified protist Cyranomonas australis. The organisms are ovoid-shaped cells, 3.5-6μm long, laterally compressed, and somewhat flexible. They have two unequal flagella, about 1.1-2.5 times body length. Typically, the cells show a gliding motility and do not exhibit any amoeboid form or pseudopodia. 18S rDNA phylogenies clearly indicate that the isolates can be assigned to the taxon Filosa, within Cercozoa. The isolates are closest to an environmental sequence (CYSGM-16; 99% identity). Cyranomonas, CYSGM-16, and uncultured eukaryote RM1-SGM46 form a clade with strong statistical supports, here called novel clade CU (Cyranomonas plus Uncultured eukaryotes). This clade may be sister to the order Marimonadida. The novel clade CU and the Marimonadida have been detected only in marine habitats. Our findings suggest that C. australis may not belong to any previously described family within Filosa and Cercozoa., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

We describe 11 new species of Thaumatomonadida using light and electron microscopy and rDNA gene sequences (18S, ITS1, 5.8S, ITS2). We found clear distinctions between major clades in molecular and morphological traits that support now splitting Thaumatomastix into three genera: new marine genera Ovaloplaca (oval plate-scales) and Thaumatospina (triangular plate-scales), both with distinctive radially-symmetric bobbin-based spine-scales, restricting Thaumatomastix to freshwater species with putatively non-homologous eccentric-spine scales and thicker triangular plate-scales. New genus Scutellomonas lacks spine-scales, having oval plate-scales with deeply-dished upper tier as in Ovaloplaca, with which it forms a clade having short/absent anterior cilium. Cowlomonas gen. n. is possibly naked. We describe two new Allas species, two new Thaumatomonas, and one new Reckertia species, and transfer R. hindoni to Thaumatomonas. Triangular-scaled Reckertia has varied plate-scales and ciliary scales. Thaumatomonas rDNA trees reveal two clades: zhukovi/seravini (predominantly triangular scales); coloniensis/oxoniensis/lauterborni/constricta/solis (scales mostly oval). We hypothesise that the ancestor of Thaumatomonadidae had radially-symmetric bobbin-based spine-scales and triangular plate-scales, bobbin-based spine-scales being lost in one lineage and eccentric-spine scales evolving in Thaumatomastix. Bobbin-based spine-scales arguably evolved from triangular plate-scales and single-tier ciliary scales (Ovaloplaca and Reckertia only) from plate-scale rudiments. We present a unified scheme for scale evolution and development in Imbricatea., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

This study aimed to investigate the relationship between the size structure of testate amoebae in distinct habitats, i.e. plankton, aquatic macrophytes and aquatic sediment. The samples were taken from a floodplain lake of the upper Paraná River. The assumptions we strived to scrutinize were that (i) larger mean sizes of testate amoebae would be recorded in the sediment of the lake; and (ii) temporally, smaller individuals would be registered during the high water period in all habitats. The sampling was done monthly, from April 2007 to March 2008, in triplicates for each habitat. Testate amoebae were represented by individuals sized between 20 and 400 μm. The smaller individuals predominated in plankton samples, while in the aquatic sediment the larger ones were chiefly represented. These differences were probably associated with metabolic activities, i.e. the energy needs of these unicellular organisms, in each habitat. Two-way ANOVA yielded significant differences between hydrological periods. During the high water period, the increase in rainfall and consequently in water flow, decreased the stability of the system and increased turbulence and water column circulation. Therefore, environmental stability seems to be one of the main factors driving the temporal variation in the size structure of these specific organisms., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

This study aimed to investigate the testate amoebae (Arcellinida and Eugliphida) species diversity in plankton, macrophytes and aquatic sediment samples from a shallow lake of the Upper Paraná River floodplain. Samples were carried out from April 2007 to March 2008. We recorded 89 taxa, belonging to 10 families. Eighty-two taxa were found in the aquatic sediment, 71 in the macrophytes and 53 in the plankton. Highest values of alpha diversity were observed in the aquatic sediment. Although the plankton had the highest number of accidental species, accessory and constant species were also observed in this habitat. Most of the species classified as constant for the plankton belonged to the genus Arcella. Most of the constant species in the macrophytes and aquatic sediment belonged to the genus Difflugia. This study supports the idea that the presence of these protists in the plankton should not be attributed only to stochastic processes because (i) the species diversity recorded in this habitat was remarkably high in relation to the total biodiversity of the lake, and (ii) we also recorded frequent and constant species in the plankton., (Copyright © 2010 Elsevier GmbH. All rights reserved.)