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Odonata records of the Samoan Archipelago are updated and an updated checklist provided. It is part of an ongoing assessment of the fauna, taxonomy and distributionof the Pacific island dragonflies. The checklist follows recent reviews published/prepared about the Solomon Islands, New Caledonia, Fiji and Kingdom of Tonga.
This study draws on recent dragonfly records following general insect surveys spanning 2008-2012 funded by Critical Ecosystem Partnership Fund (CEPF) via Conserva-tion International (CI) to the authors and to Secretariat Pacific Regional Environment Program (SPREP) and also by funding from Japan International Cooperation Agency (JICA). Other unpublished data from Samoan Archipelago and Niue are included as well. All, but one, of the newly collected Odonata species are widespread within the Pacific region. Hemicordulia cupricoloris the only species from the recent collections which is endemic to Samoa, previously reported for Savai'i and Upolu Islands. It has neverbeen confirmed since its original description in 1927. The new study shows the species as an inhabitant of high altitude zones of Savai'i. It is recommended inland areas of Savai'i and other islands within the Samoan Archipelago should be targeted in further field studies.
Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.