New species and records of the Neotropical genus Cyrnellus (Trichoptera: Polycentropodidae) and the re-establishment of C. minimus and C. marginalis.

Cyrnellus is a small genus of Polycentropodidae distributed in the Nearctic and Neotropical regions, absent from the Chilean subregion. Two new species are here described: C. boliviensis sp. nov. and C. guyanensis sp. nov. Cyrnellus minimus Banks 1913 considered as a junior synonym of Cyrnellus fraternus (Banks 1905) by Flint (1971) and C. marginalis (Banks 1930) considered as a junior synonym of Cyrnellus fraternus by Flint (1964) are revalidated at the specific level. We provide a key and illustrations for adult males and nine new country records for Bolivia.

Ollieopteryx, a new genus of caddisflies from Madagascar (Trichoptera: Dipseudopsidae).

New taxa of Dipseudopsidae from Madagascar are described, including a new genus, Ollieopteryx, and three new species, Ollieopteryx fianarana, O. inopinata, and O. dakshan. The hypothetical phylogenetic tree of the Dipseudopsidae (Weaver Malicky 1994) is revised to include Ollieopteryx, an isolated relic. Scenarios on the historical biogeography of the family are hypothesized.

The genera Smicridea McLachlan and Chimarra Stephens in French Guiana (Trichoptera: Hydropsychidae, Philopotamidae).

A brief collecting exploration to small streams in the coastal zone of French Guiana resulted in the capture of eight species belonging to the genus Smicridea McLachlan 1871 and two belonging to the genus Chimarra Stephens 1829. Given the scarcity of knowledge about the trichopteran fauna of this territory, the results of the study of this material are provided. A new species of the genus Smicridea is described: Smicridea (Rhyacophylax) sanctorum sp. n. Six species of Smicridea are new for French Guiana: Smicridea (R.) abrupta Flint 1974, Smicridea (R.) caligata Flint 1974, Smicridea (R.) columbiana Ulmer 1905, Smicridea (R.) pseudolobata Flint 1978, Smicridea (S.) obliqua Flint 1974, and Smicridea (S.) truncata Flint 1974. These results bring the number of French Guianan Smicridea species to 16. The two Chimarra species represent the first species records of the genus in French Guiana.

Transfer of mercury and methylmercury along macroinvertebrate food chains in a floodplain lake of the Beni River, Bolivian Amazonia.

We have evaluated the mercury and methylmercury transfers to and within the macroinvertebrate communities of a floodplain lake of the Beni River basin, Bolivia, during three hydrological seasons and in two habitats (open water and vegetation belt). Using the stable isotopes delta(13)C and delta(15)N, six trophic chains were identified during a previous study. Four are based on only one source: seston, organic matter from the bottom sediment, periphyton and macrophytes. Two are based on mixed sources (seston and periphyton in one case, periphyton and macrophytes in the other). During sampling, we found only one taxon that had surface sediment organic matter as food source and very few taxa whose trophic source was constituted by macrophytes. The periphyton was the most important source during all seasons; it produced the longest chain, with three trophic positions. Whatever the season and trophic source, all collected macroinvertebrates contained methyl mercury and the latter was biomagnified in all trophic chains that we identified. The biomagnification of methylmercury through invertebrate trophic chains accurately reflected the existence and length of these chains. Biomagnification was virtually non-existent in the sediment-based chain, low and restricted to the dry season in the macrophyte-based chain. It was significant in the seston-based chain, but limited by the existence of only two trophic levels and restricted to the wet season. Finally, it was very effective in the periphyton-based chain, which offers the highest rate of contamination of the source but, above all, the largest number of trophic levels.