Here we provide a checklist of the odonates from Amazonas state, Brazil. We registered 324 species and 101 genera, making Amazonas the Brazilian state with the most Odonata species recorded. The families with the highest number of species were Coenagrionidae with 32 genera and 101 species, followed by Libellulidae with 28 genera and 100 species and Gomphidae with 12 genera and 45 species. Some regions of Amazonas state remain poorly explored, such as the southern area, and large municipalities, such as São Gabriel da Cachoeira. This work underlines the importance of the biological diversity from Amazonas state and the Amazonian Biome for Odonata species richness in Brazil and shows that many areas in the world’s largest tropical forest have not yet been sampled.

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The larva, the adult male and the adult female of Aeschnosoma hamadae sp. nov. are described and illustrated. This species belongs to the A. elegans group of species. A comparison with other species of this group is given.

The larva of Dicterias Selys, 1853, a monotypic genus, is described and illustrated for the first time. It is morphologicallyvery close to the larva of Heliocharis Selys, 1853. The larvae of these two genera are compared, and a larval diagnosis forthe family is provided. The family Heliocharitidae (= Dicteriadidae) shares derived characters with some Calopterygoideaand is probably related to Calopterygidae. The larvae of Heliocharitidae are also amazingly similar to those of some Mega-podagrionidae, and long-legged Megapodragrionidae related to Megapodagrion could be related to the family Heliocharitidae and could represent a basal stem within the Calopterygoidea.

Alocasia macrorrhizos (L.) G.Don grows and proliferates in shaded areas in several forest fragments in urban zones. The adult plant has axils that accumulate rain water (phytotelmata) and serve as breeding sites for several families of aquatic insects. The objective of this study was to determine the composition of the entomofauna associated with water accumulations in axils of A. macrorrhizos in urban areas of Manaus, Brazil. Individuals of A. macrorrhizos were sampled in five forest fragments, between April/2005 and March/2007 in urban areas of Manaus, totaling 184 sampling units. A manual suction hose was used for the removal of entomofauna. A total of 1,941 immatures of Diptera were collected representing the following families: Culicidae (96.5%), Chironomidae (2%), Psychodidae (0.7%), Ephydridae (0.7%) and Corethrellidae (0.1%). Five Culicidae species were identified: Wyeomyia melanocephala Dyar & Knab, 1906 (91.7%), Wy. ypsipola Dyar, 1922 (4.3%), Aedes albopictus (Skuse, 1894) (2.3%), Ae. aegypti (Linnaeus, 1762) (1.5%) and Johnbelkinia longipes (Fabricius, 1805) (0.1%). The members of Culicidae were the most abundant, confirming the importance of this group in communities associated with phytotelmata, with a positive relation to the volume of water (p < 0.05). The occurrence of Ae. aegypti and Ae. albopictus in axils of A. macrorrhizos demonstrates the potential of this Araceae as a breeding site of these medically important species. However, the real contribution of this Araceae in the maintenance and dispersion of populations of these two species of mosquitoes throughout the year should be further studied.

The larva of Perilestes attenuatus Selys, 1886 is described and illustrated based on exuviae of reared larvae and lastinstar larvae collected in Manaus, Amazonas state, Brazil. The larva of P. attenuatus can be distinguished from that of P. fragilis, the only other species of which the larva has been described, by the presence of a pair of tubercles on the ligula and by the arrangement of the spines and hooks on the abdominal segments.