Rhapsody in emerald: phylogenetic framework for Lestidae with reference to the systematic position of Chalcolestes Kennedy

We reconstruct a phylogenetic framework for the zygopteran family Lestidae based on a molecular dataset comprised of sequence data from the genes COI, 16S, 18S, 28S, and ITS1+2 from 41 ingroup taxa and 8 outgroup taxa with emphasis on the systematic position of the genus Chalcolestes Kennedy. We recover Lestidae as monophyletic with good statistical support. The family falls into two subequal clades. One, comprising the genus Sympecma Burmeister and Lestes Leach sensu lato (including the genus Archi­lestes Selys) is poorly to moderately supported. While the other, comprising the genera Austrolestes Tillyard, Indolestes Fraser, Orolestes McLachlan, and Chalcolestes is strongly supported. Chalcolestes is recovered as sister to the Oriental genus Orolestes with strong support. Our results thus support that Chalcolestes is a valid genus not closely related to Lestes. Monophyly of Lestes requires inclusion of the New World genus Archilestes, and our results support the need for a thorough revision of Lestes.

Habitat conditions in streams influence Odonata larval assemblages in the eastern Amazon

The growth of agricultural and mining activities in the Amazon has impacted land-use and caused significant changes in the local environmental conditions of streams. In the face of these changes, our study aimed at assessing how environmental changes affect Odonata larval assemblages in streams in the eastern Amazon. We hypothesized that habitat conditions in streams are strong predictors of Odonata larval assemblages. We sampled 30 headwater streams (1st through 3rd order) in the eastern Amazon. We corroborated our hypothesis that regional- and local-scale environmental changes are important predictors of the Odonata larval assemblage structure. These results indicate that environmental conditions within the stream channel are important to maintain Odonata larval assemblages, as they provide important resources for larval development. For new studies, we recommend the assessment of temporal dynamics to evaluate whether these patterns are stable across time. Finally, evaluating various environmental scales of the original impact is extremely relevant for preventing the deterioration of or recuperating aquatic assemblages in Amazonian streams, considering the ongoing rapid environmental changes and deforestation in the region. Here we demonstrate that in-stream environmental conditions are important to assemblage structure and this must be considered in environmental restoration plans.

To harass or to respect: the economy of male persistence despite female refusal in a damselfly with scramble mate competition

In sexual conflict, males are often thought to gain fitness benefits from harassing females over mating. Yet when harassment itself incurs costs to males and if alternative, receptive females are available in a local population, theory predicts that when confronted with a female refusal, a male’s choice of persisting or retreating is determined in part by the likelihood of achieving a mating. We tested that prediction in the damselfly Enallagma hageni, whose males compete by intense scramble competition, resulting in widespread mating harassment toward females, which have a high level of control over mating. Using captive individuals of E. hageni in outdoor insectaries, we quantified male persistence in mating after refusals by pre- and post-oviposition focal females whose egg content we quantified after observations. We documented a novel, context-dependent head-turning refusal signal of sexual non-receptivity, most often displayed in tandem pairs by post-oviposition females that typically carried few mature eggs for males to fertilize. Male persistence was less likely to result in mating with post-oviposition females compared with pre-oviposition females carrying a clutch of mature eggs. Accordingly, males were less likely to persist following refusal signals given by post-oviposition females, supporting the theoretical prediction. Compared with a refusal signal known as wing spread, head-turning was significantly more effective in deterring harassing males. Our results suggest that despite on-going sexual conflict over mating, cooperation benefits both sexes when females use the honest signal of non-receptivity because they carry few mature eggs that males could fertilize.

Description of the larva of Vestalis gracilis (Rambur, 1842) (Zygoptera: Calopterygidae) from Thailand

Vestalis gracilis (Rambur, 1842) is a forest stream damselfly belonging to the family Calopterygidae. Its last-stadium larvae and exuviae are described and illustrated based on laboratory-raised specimens from Thailand, and observations of agonistic behavior are provided. The taxonomical characters of V. gracilis larvae are similar to those of V. amoena. They exhibit synapomorphic characters such as posterlaterally directed protuberances on the postocular lobes, posterior margin of median lamella obliquely truncate, and two setae on labial palps. Vestalis gracilis and V. luctuosa bear eight antennal segments whereas seven antennal segments are found in V. amoena. The most significant difference between V. gracilis and V. luctuosa is that V. luctuosa has posterolaterally directed protuberances on the postocular lobes and an obliquely truncate posterior margin of the median lamella.

A scientometric analysis on pre- and post-copulatory traits in Odonata

In the last decades, studies on sexual selection in odonates have shown a relationship between mating success and costly sexual ornaments, mainly male characters. Here, we conducted a scientometric analysis to assess the state of art of studies on sexual selection in odonates, especially on the role of male ornamentation (pre-copulatory traits) and sperm competition (post-copulatory traits). We found 51 papers focused on sexual ornamentation and 34 on sperm competition. Only one study simultaneously addressed both pre- and post-copulatory traits, nevertheless without an integrative approach. Results show that calopterygids are extensively studied regarding pre-copulatory traits (i.e., male wing pigmentation), while libellulids are mostly studied in post- copulatory traits (e.g., sperm competition) focused research. These preferences seem to be related to characteristics like presence of ornamentation and territoriality, large body size, variation and complexity of sperm removal structures, respectively. For the post-copulatory traits, sperm removal is frequently addressed, but few other strategies, like the investment in sperm quality and quantity, are investigated. Finally, we demonstrate that it is necessary to conduct studies focused on addressing the relationship between pre- and post- mating sexual traits.

Forest edges and their effects on the arrival of dragonflies at north-temperate experimental ponds

The matrix, an environment in the landscape that individuals move through but do not reside in, can affect species dispersal and the arrival of individuals at habitat patches. Elements around this matrix that provide refuge or resources may shape the arrival of animals at habitat patches, even when those patches are equivalent in quality. Adult dragonflies (Odonata: Anisoptera) frequently use open terrestrial environments during movement and dispersal in north-temperate regions; however, they can also roost along forest edges. Because of the potential value of forest edges to adult dragonflies, we tested whether pond proximity (i.e., connectivity) to multiple forest edges was positively related to the abundance or diversity of arriving dragonflies. We observed dragonflies arriving at 9 experimental pond sites located within an open field landscape in Ontario, Canada. Experimental ponds differed in their distance to source ponds and to forest edges, a potential refuge for dragonflies. We found no effect of connectivity to forest edges or distance to source ponds on the abundance or diversity of dragonflies arriving at a site. Dragonfly dispersal was therefore not limited at the spatial scale of our study (<305 m to source ponds). In addition, dragonflies did not seem to discriminate among sites based on the amount of nearby forest edge, although all sites within the generally open landscape had at least some forest edge in close proximity (10–79 m). Our results provide greater insight regarding the decisions that dragonflies make in response to landscape elements while dispersing to reproductive habitats.

Odonata (Insecta) communities along an elevational gradient in the Atlantic forest of southeastern Brazil, with the description of the female of Heteragrion mantiqueirae Machado, 2006

Despite the important role of the order Odonata in ecosystems, there is a lack of information about dragonfly communities in several regions, high elevation sites, and environmentally protected areas in Minas Gerais State, Brazil. Our objective was to assess the abundance and richness of dragonfly and damselfly communities along an elevational gradient in the Atlantic Forest,southeastern Brazil. This study was conducted in the Fernão Dias Environmental Protection Area,Mantiqueira Mountain region, Gonçalves, Minas Gerais State, in sites covered by Seasonal Semideciduous and mixed forests. This is the first study of Odonata communities in the region. Samplings were carried out on 17 days from October 2019 to March 2020 at three elevation ranges (low,mid, and high). A total of 293 specimens, distributed in 39 species and 9 families, were sampled. Elevation did not influence the richness or abundance of dragonflies but altered community composition. Some species were found to be exclusive to high-elevation sites, such as Heteragrion mantiqueirae Machado, 2006, which was recorded for the first time in Minas Gerais and we provide a description and diagnosis of the single female collected in tandem. A novel species of the genus Brechmorhoga was found to occur at mid and high elevations. The composition of dragonfly communities depends on the degree of preservation and extension of forest areas. Therefore, conservation of forests in Gonçalves is crucial for preserving Odonata diversity in Minas Gerais State.

Environmental impacts from human activities affect the diversity of the Odonata (Insecta) in the Eastern Amazon

Land use influences the biodiversity of stream systems by changing the chemical composition of the water and the physical structure of the habitat. The present study evaluated the influence of these processes on the diversity metrics of Odonata at regional and local scales, testing the hypothesis that the two odonate suborders Anisoptera and Zygoptera will respond differently to habitat and landscape variables. The study focused on 13 sites in the municipality of Barcarena, Pará, Brazil. We found no significant impact from regional factors, although anisopterans were more affected by water temperature and Habitat Integrity Index (HII). The HII indicated that the local forest was stable, but anisopteran richness was negatively correlated with HII. It was indicating that these species favoured open areas with less riparian cover. Even though zygopterans did not exhibit a similar systematic pattern, the reduced abundance of Chalcopteryx rutilans, a species associated with better-preserved habitats, may indicate that some sites lack the habitat integrity necessary to establish populations of this species. These findings highlight the importance of preserving the riparian forest to maintain the health of the stream systems. We recommend more studies that focus on the broader geographic and temporal scales to account for factors such as the anthropogenic gradient and historical land use patterns.

Description of Coeliccia diehlae sp. n. from the Central Highlands of Vietnam with keys to the males and females of the pyriformis-group (Odonata: Zygoptera: Platycnemididae)

Description of Coeliccia diehlae sp. n. from the Central Highlands of Vietnam with keys to the males and females of the pyriformis-group (Odonata: Zygoptera: Platycnemididae) Coeliccia diehlae sp. n. (holotype male from Ko Roong Commune, Ka Bang District, Gia Lai Province, Central Highlands of Vietnam, deposited in the Zoological Collection of Duy Tan University) is described based on both sexes. This species belongs to the pyriformis-group and comes closest to Coeliccia phamiha Phan & Tran, 2018. Keys to the males and females of the pyriformis-group are provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:09621225-FFE8-477F-ACD8-605BC100A647

Description of the final instar larva of Cephalaeschna risi Asahina, 1981 with notes on its semi-terrestrial lifestyle (Odonata: Aeshnidae)

The final instar larva of Cephalaeschna risi Asahina, 1981 is described for the first time based on material from Taiwan. In Taiwan, the larva of C. risi can be separated from other aeshnid larvae by its relatively short antennae and presence of small protuberances on the legs. Diagnostic characters to distinguish it from other known larvae of Cephalaeschna are also discussed. A comprehensive description, detailed illustrations, bionomics and observations of the semi-terrestrial lifestyle of C. risi are presented. Finally, a key to the genera of Aeshnidae in Taiwan is proposed.