Environmental characteristics drive variation in Amazonian understorey bird assemblages.

Tropical bird assemblages display patterns of high alpha and beta diversity and, as tropical birds exhibit strong habitat specificity, their spatial distributions are generally assumed to be driven primarily by environmental heterogeneity and interspecific interactions. However, spatial distributions of some Amazonian forest birds are also often restricted by large rivers and other large-scale topographic features, suggesting that dispersal limitation may also play a role in driving species' turnover. In this study, we evaluated the effects of environmental characteristics, topographic and spatial variables on variation in local assemblage structure and diversity of birds in an old-growth forest in central Amazonia. Birds were mist-netted in 72 plots distributed systematically across a 10,000 ha reserve in each of three years. Alpha diversity remained stable through time, but species composition changed. Spatial variation in bird-assemblage structure was significantly related to environmental and topographic variables but not strongly related to spatial variables. At a broad scale, we found bird assemblages to be significantly distinct between two watersheds that are divided by a central ridgeline. We did not detect an effect of the ridgeline per se in driving these patterns, indicating that most birds are able to fly across it, and that differences in assemblage structure between watersheds may be due to unmeasured environmental variables or unique combinations of measured variables. Our study indicates that complex geography and landscape features can act together with environmental variables to drive changes in the diversity and composition of tropical bird assemblages at local scales, but highlights that we still know very little about what makes different parts of tropical forest suitable for different species.

Ontogeny and Molecular Phylogeny of Apoamphisiella vernalis Reveal Unclear Separation between Genera Apoamphisiella and Paraurostyla (Protozoa, Ciliophora, Hypotricha).

Morphology and divisional morphogenesis of the hypotrich ciliate Apoamphisiella vernalis are investigated based on two populations from Brazil. Typical specimens of A. vernalis replicates its ventral ciliature from six fronto-ventral-transverse (FVT) anlagen independently formed for proter and opisthe, plus one or more short anlagen located between IV and V, which form surplus transverse cirri. Dorsal morphogenesis occurs as in typical oxytrichid dorsomarginalians, viz., with formation of three anlagen and fragmentation of the rightmost one. Dorsomarginal kineties are formed near anterior end of right marginal cirral row anlagen. Various anomalous specimens exhibiting more than two long ventral rows were found, which are explained by increasing the number of FVT anlagen and/or the number of cirri produced by anlagen. Comparative ontogeny and phylogenetic analyses based on the 18S rDNA reveal that Apoamphisiella vernalis is closely affine to North American and European strains of the Paraurostyla weissei complex. Their reduced genetic distances and conspicuous morphological variability show that both genera can overlap, which implies the necessity of re-evaluating the contextual relevance of some morphological characters commonly used for genus-level separation within hypotrich taxa.

Description and phylogenetic position of Corlissina maricaensis gen. nov., sp. nov. (Karyorelictea, Geleiidae), a novel interstitial ciliate from Brazil, with redefinition of the family Geleiidae.

Corlissina maricaensis gen. nov., sp. nov. was obtained from samples of sediment collected in a brackish lagoon of Maricá city, Rio de Janeiro state, Brazil. The morphological description was based on live observations, after protargol staining, and scanning electron microscopy. The novel species has a cylindrical body shape that is slightly contractile, 230-550 × 35-65 µm, a cytoplasm with many globular inclusions, one row of irregular cortical granules between each somatic kinety, approximately 40-62 somatic kineties, two globular macronuclei measuring 9-24 µm and one micronucleus of approximately 4-9 µm. A subapical oral cavity was approximately 20-80 × 9-25 µm, with an adoral zone on the left side of the buccal field, which was composed of 32-60 polykineties and a paroral at the right side that was composed of 40-57 short polykineties. The new genus is distinguished from other geleiids by a loop-shaped posterior end of the paroral ciliature, made up of two rows of short polykineties, and the oralization of the central superior kinety (K0i), forming a row of dikinetids that borders the adoral zone internally, followed by several rows of monokinetids. In the phylogenetic analyses, the novel species was recovered as the sister group of Parduczia orbis with full support values based on 18S rRNA gene sequences. This work also indicates some problems in the definitions of the Geleiidae and proposes a new diagnosis for this karyorelictid family.