Tropical forests are among the most biodiverse biomes on the planet. Nevertheless, quantifying the abundance and species richness within megadiverse groups is a significant challenge. We designed a study to address this challenge by documenting the variability of the insect fauna across a vertical canopy gradient in a Central Amazonian tropical forest. Insects were sampled over two weeks using 6-m Gressitt-style Malaise traps set at five heights (0 m–32 m–8 m intervals) on a metal tower in a tropical forest north of Manaus, Brazil. The traps contained 37,778 specimens of 18 orders of insects. Using simulation approaches and nonparametric analyses, we interpreted the abundance and richness of insects along this gradient. Diptera, Hymenoptera, and Coleoptera had their greatest abundance at the ground level, whereas Lepidoptera and Hemiptera were more abundant in the upper levels of the canopy. We identified species of 38 of the 56 families of Diptera, finding that 527 out of 856 species (61.6%) were not sampled at the ground level. Mycetophilidae, Tipulidae, and Phoridae were significantly more diverse and/or abundant at the ground level, while Tachinidae, Dolichopodidae, and Lauxaniidae were more diverse or abundant at upper levels. Our study suggests the need for a careful discussion of strategies of tropical forest conservation based on a much more complete understanding of the three-dimensional distribution of its insect diversity.

Five new species are described herein for the Neotropical genus Psilochlorops, up to now known only from the type–spe-cies, P. clavitibia Duda—P. brunneus sp. n., P. elongatum sp. n., P. flavisoma sp. n., P. nigrifemur sp. n. and P. paganelliaesp. n. All new species are described in detail and illustrated. A key to the species of the genus is provided. The diagnosisof Psilochlorops, after the addition of these species, is emended. A cladistic analysis of the genus indicates that Psilochlorops is monophyletic and show the affinities between the species.

The genus Paracalamoncosis gen. nov. is described based on the species P. brasiliensis gen. nov. et sp. nov., including a brief discussion of the morphological similarities and differences with other genera in the tribe Liparaini.

Chaetochlorops Malloch is a small genus endemic to the New World with a peculiar morphology of the male terminalia. The genus is recorded from Brazil–Amazon and Atlantic forests– and Nicaragua for the first time. Detailed images of the external and internal morphology of all species are provided here. Also, an additional host plant for C. inquilinus is given.

Measuring species richness of tropical forests is a major challenge. Such measurement is a key information in many senses, from an evolutionary perspective to conservation of threatened, fragile habitats. Data has gradually shown that the canopy of tropical forest is a hugely complex component of the forest, but a precise assessment of the diversity of megadiverse groups in the canopy is still wanting. We collected large samples of insects were along a period of two weeks using 6-meter Gressitt-style Malaise traps set at five heights on a metal tower in a tropical forest north of Manaus—one trap at the ground level, one trap above the canopy (32 m) and three traps at intermediate levels (8, 16 and 24 m). The samples contained 37,778 specimens belonging to 18 order of insects. Fifty-seven families of flies (Diptera) were found, 39 of which were identified to 368 genera and 856 species. The species of these 39 families of flies fit into eight patterns of vertical distribution of abundance and species richness of the fauna, with patterns of one or two peaks of species at different levels. A total of 527 (61.6%) of the 856 fly species recognized in the samples were not collected at the ground level. The canopy-associated species of Diptera showed a high species richness and a relatively low abundance indicating that they represent vulnerable components of tropical diversity. The biology of the flies families and genera we collected in the canopy suggest that the evolution of flies went through a unique process: independent clades of Diptera explored in different ways the resources originated along the very evolution of the angiosperm forest canopy along the early Cenozoic. Unlike other primarily phytophagous groups of insects, flies radiated into a large array of biologies associated with the canopies: parasitoids, hematophagous, phytosaprophagous, kleptoparasites, sap feeders, gall-makers etc. The results only stress the need of additional strategies to protect this diversity.

Pseudogaurax Malloch is a worldwide genus of Chloropidae with 33 species in the Neotropical region and 12 occurring in Brazil. The genus is well-known for the feeding habits of its larvae which attack egg masses and larvae of several arthropods, usually breeding in the egg sacs of spiders. In this study, we expanded the distribution of P. cingulatus to northern Brazil and recorded for the first time the species preying on Tetragnatha egg sacs. In addition, diagnosis, digital images and a distribution map are provided.

Psilacrum Becker was recorded from the Neotropical Region by Wheeler (2010) based on Oscinoides annulicrus (Duda, 1933) described from Costa Rica with a further five to six species from the Region (Wheeler, 2010). Here we describe a new species from Brazil.

A first known extant Neotropical species of the atelestid genus Alavesia-Alavesia leukoprosopa, sp. nov.-is described from southeastern Brazil. The holotype (and only specimen so far) was collected with a Malaise trap in an area with strongly impacted semideciduous seasonal forest (dry forest) and open, entirely secondary vegetation. It was collected in mid spring, but has not been collected again so far. Alavesia leukoprosopa shares some derived features with the only two other extant species of the genus, known from the Brandberg Massif in Namibia, suggesting that all three extant species may compose together a small clade separate from the bulk of the Cretaceous diversity of Alavesia.