Aim Propagule size and ecological requirements are believed to be major factors influencing the passive dispersal of free-living terrestrial protists. We compared the colonization potential of three closely related testate amoeba species (Assulina muscorum, A. seminulum, A. scandinavica, ranging from 40 to 100 lm in length).Location Europe.Methods We collected individual Assulina species cells from Sphagnum peatlands across Europe. We sequenced a 550-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) to estimate the within-species variability, as a proxy for gene flow. We reviewed existing ecological and palaeoecological data to assess the ecological tolerance of Assulina species and how rapidly they colonized developing peatlands.Results We obtained COI sequences for 30 individuals of A. seminulum from eleven sites, for 39 of A. muscorum from six sites, and for six of A. scandinavica from two sites. We observed three haplotypes for A. seminulum and two for A. muscorum, often co-existing in the same sites. The sequences of A. scandinavica from the two sites were identical. Assulina muscorum and A. seminulum haplotypes varied by only 1-2 nucleotides, resulting in >99.5% similarity. Genetic diversity within A. seminulum was higher than that within A. muscorum. Ecological and palaeoecological records showed that A. muscorum was much more frequent and abundant than A. seminulum, and had a somewhat broader ecological tolerance for pH, moisture and water-table depth. Assulina muscorum always appeared early during the developmental history of peatlands, either before or simultaneously with A. seminulum.Main conclusions The lack of genetic structure observed with a variable marker such as COI suggests high gene flow between the sites and thus rapid transport (at an evolutionary scale) over large distances, in agreement with the palaeoecological records. Thus, geographical distance alone does not seem to prevent the dispersal of testate amoebae, at least within Europe. Nevertheless, genetic diversity was significantly lower within A. muscorum than within A. seminulum, suggesting that its smaller size and abundance and/or broader ecological tolerance influence its effective dispersal capacity. These results are in agreement with the often earlier colonization of peatlands by A. muscorum and its broader ecological tolerance.

In small metazoan invertebrates classical taxonomic analyses can be ambiguous due to the limited number of morphological characters available. This difficulty can yield incorrect estimates of species richness or taxa distribution. The Boeckella genus has been described as the dominant taxon of zooplankton assemblages in the Andean biogeographical region. In this genus, taxonomic classification and delimitation of boundaries between species has long been problematic and controversial. Among South American centropagids Boeckella gracilipes has been regarded as one of the most broadly distributed species, its presence having been reported from Ecuador to Tierra del Fuego. However, in the high Andean plateau some centropagid populations identified as Boeckella gracilipes have also been considered as B. gracilipes titicacae or even identified as a different species, namely Boeckella titicacae. In an attempt to resolve the taxonomic status of the Centropagidae family from the high Andean plateau, we combined traditional and multivariate morphological analyses (integral approach) with the molecular phylogenetic approach. The results obtained allow us to conclude that centropagids collected from the high Andean plateau actually represent a different species, B. titicacae, not B. gracilipes. The phylogenetic reconstruction of the South American Centropagidae family indicated that B. gracilipes represents a sister taxon to B. titicacae. The present study stresses the usefulness of integrating alfa-taxonomy with morphometric and molecular approaches in order to resolve species boundaries, to determine geographical distributions and to investigate evolutionary processes.

Some specimens of Cletocamptus were found in Salar de Surire (Chilean Andean plateau) during two sampling trips in October 2004 and October 2005. Although the Chilean material was preliminarily identified as C. axi, after careful inspection, it was clearly a new Chilean Cletocamptus species, C. cecsurirensis. The new species was found to be similar to C. levis, C. sinaloensis, C. fourchensis, C. deborahdexterae, and C. axi in the combination of the armature formula of the mandibular palp, shape of the lateral spinulose element of the maxillulary arthrite, and armature formula of P1-P4. Cletocamptus cecsurirensis and C. levis can be distinguished from C. sinaloensis, C. fourchensis, and C. deborahdexterae by the P1 EXP:ENP length ratio. Cletocamptus cecsurirensis and C. levis can be separated by the P5 baseoendopod:EXP length ratio. Cletocamptus cecsurirensis shows the sexual dimorphism typical for the genus. The new species also shows sexual dimorphism in the rostrum, similar to that found for C. retrogressus, C. albuquerquensis, and C. levis.A complete description of the new Chilean species and some amendments to the original description of C. axi are given.