Rhainer Guillermo-Ferreira

The unusual tracheal system within the wing membrane of a dragonfly

Some consider that the first winged insects had living tissue inside the wing membrane, resembling larval gills or developing wing pads. However, throughout the developmental process of the wing membrane of modern insects, cells and tracheoles in the lumen between dorsal and ventral cuticle disappear and both cuticles become fused. This process results in the rather thin rigid stable structure of the membrane. The herewith described remarkable case of the dragonfly Zenithoptera lanei shows that in some highly specialized wings, the membrane can still be supplemented by tracheae. Such a characteristic of the wing membrane presumably represents a strong specialization for the synthesis of melanin-filled nanolayers of the cuticle, nanospheres inside the wing membrane and complex arrangement of wax crystals on the membrane surface, all responsible for unique structural coloration.

Erythrodiplax ana sp nov (Odonata: Libellulidae) from Brazilian palm swamps

Erythrodiplax ana sp. nov. (male holotype, six male and three female paratypes), collected in Vereda wetlands (a unique Neotropical savanna environment) in Uberlândia (Minas Gerais) and Chapada dos Guimarães (Mato Grosso), Brazil, is described and illustrated. The new species fits in Borrors Basalis Group, and can be distinguished from other species by the combination of the following traits: blue pruinosity dorsally on thorax and third to eighth abdominal segments; sides of the thorax olive-green; face ivory or olive-green; wings hyaline with a small apical brown spot on all four wings, well defined in females; male genitalia with sclerotized erectile posterior lobe and inflatable sac-like median process. Last instar larvae were reared in the laboratory, resulting in the description of the larva. We also followed this population for 13 months and present resulting biological notes and comments on ontogenetic color change in males, as well as longevity.

Description of the female of Dicterias atrosanguinea Selys 1853, with notes on male genital ligula and male behavior (Odonata: Dicteriadidae)

The female of Dicterias atrosanguinea Selys, 1853 is described and illustrated based on two specimens collected in Pará and Amazonas States, Brazil. We compare the female with the most closely related species, Heliocharis amazona Selys, 1853, and present SEM images of the genital ligula for both D. atrosanguinea and H. amazona males. Additionally we provide behavioral observations on D. atrosanguinea males.

Females of two species of Argia from Chapada dos Guimarães National Park, Brazil (Odonata: Coenagrionidae)

The female of Argia tupi Calvert, 1909 (BRAZIL, Mato Grosso, Chapada dos Guimarães National Park, Cachoeira do Marimbondo (15.4330° S, 55.7198° W, 370 m), 01 xi 2015) is described, illustrated and diagnosed based on comparison with sympatric species of Argia Rambur, 1842. We also augmented the description of Argia bicellulata (Calvert, 1909) female (BRAZIL, Mato Grosso, Chapada dos Guimarães National Park, Rio Paciencia (15.3438° S, 55.8322° W, 280 m), 25 x 2015).

Egg-laying traits reflect shifts in dragonfly assemblages in response to different amount of tropical forest cover

Oviposition site selection by aquatic insects is usually influenced by both aquatic and terrestrial cues. Landscape changes (e.g. native vegetation loss) can affect the level of the reproductive success in aquatic insects, changing local species composition and richness. We investigate whether forest cover loss around streams influences the number of species with exophytic (species which lay eggs directly on the water surface), endophytic (species which lay their eggs directly into plant tissue), or epiphytic (species which lay eggs on the exposed surface of rocks, leaves, trunks or other substrates protruding from the stream surface) oviposition behaviour in dragonfly assemblages. We sampled adult dragonflies in 116 streams in a Neotropical savanna region in Brazil. The relationship between species richness for each behavioural category, and the proportion of forest cover around the streams, was tested using regression analysis. We collected 2413 dragonfly (Anisoptera and Zygoptera) individuals, belonging to 8 families, 30 genera, and 63 species. Of these, 25 species were classified as exophytic, 28 as epiphytic, and 10 as endophytic. Our results show that the number of species with exophytic or epiphytic behaviour was strongly related to riparian forest loss. Forest loss changes the habitat, and here, specifically changes site suitability for oviposition. We highlight the importance of using behavioural traits as a bioindicator tool for the assessment of anthropogenic impacts on tropical forest.

Come to the dark side: habitat selection of larval odonates depends on background visual patterns: Background preference in dragonflies

1. Determining which environmental traits enable animals to inhabit and choose preferred habitats is key to understanding ecological processes. Habitat complexity and background colour patterns can act as selective pressures on animal behaviour, and ultimately affect habitat choice.

The Influence of Body Size and Agility in Displacement Capacity of Male Damselflies (Odonata, Protoneurinae)

Alternative mating tactics (AMT) occur in several animal taxa as a way to respond to physiological or environmental factors that affect reproductive success. In other words, males can exhibit different mate acquisition tactics associated with phenotypic variations. Here we present the case of Epipleoneura williamsoni, a non-territorial Neotropical damselfly in which larger males actively search for females along the margins of streams and smaller males remain perched on the vegetation and adopt a sit-and-wait strategy. Males were captured, marked and behavioral observations were conducted to take notes on the spatial displacement of individuals. We then measured male body size and agility to test whether these traits could be used to predict flight ability and thus AMT’s. Agility was measured by the ȓ2(S) coefficient, which is a surrogate of flight ability and maneuverability. The results show that body size was positively correlated with male flight ability and agility. However, male agility did not predict the adopted AMT. These results suggest that the strategies adopted by E. williamsoni males may be a reflection of body condition. This study adds evidence on how selection may act on different phenotypes within a population and how body size variations may result in different displacement capacities and flight agility.

Female color polymorphism of Ischnura capreolus Hagen, 1861 (Odonata: Coenagrionidae) with notes on behavior and ontogenetic color changes

Polymorphism in coenagrionids is widely known, mainly for Ischnura. Here, we present the case of I. capreolus, a Neotropical species of which, until now, little information concerning color polymorphism and ontogenetic color changes was known. We used a marking and recapture method to evidence ontogenetic coloration changes in females. We show that, in addition to the gynochrome morph, I. capreolus females also exhibit at least one additional morph: an androchrome color pattern. Gynochrome females (97.1% of marked females) are green-yellow when young and change to a brownish pattern with age, within a week. Androchrome females (2.9% of marked females) exhibit blue coloration, similarly to males. Our study provides the first evidence of ontogenetic color change in I. capreolus. Furthermore, field observations show that I. capreolus is similar to other Ischnura species regarding sexual harassment behavior.

Review of Rhinotora (Diptera, Heleomyzidae) with description of a new species and key to all known heleomyzid species from Brazil.

Rhinotora Schiner, 1868, are a rare group of flies, previously including seven species distributed in the Americas, six of them occurring in Brazil. This work aims to provide a taxonomic review for Rhinotora Schiner, with addition of two species in the genus: Rhinotora fonsecai, which is transferred back to its original genus, and R. paschoali sp. nov. New distributional records are presented for R. lopesi and R. travassosi. A key to the all known heleomyzid species recorded from Brazil is provided.