The genus Rhyacobates Esaki, 1923 has so far been reported from India based only on larvae identified to genus level. This study reports Rhyacobates malaisei Andersen and Chen, 1995 for the first time from India, based on the adult specimens from the Palmajua and Teesta Rivers, West Bengal. A detailed morphological description, including morphometric data, and illustrations of male genitalia is provided.

The movement of organisms within river ecosystems has been understood mainly in terms of three dimensions: longitudinal, lateral, and vertical within the water column. However, little is known about the vertical extent of the aerosphere, which is utilised by adult aquatic insects. In this study, vertical adhesive traps were installed on a 59 m-high bridge spanning a mountain stream to investigate a community consisting of adult mayflies, stoneflies, and caddisflies that utilised the aerial zone directly above the river. The results showed that a single female Stenopsyche marmorata Navás, 1920 was captured at a height of 55 m, however, adult insects were concentrated within the zone up to 25 m above the water surface. These observations make a significant contribution to knowledge regarding the flight altitude of adult Ephemeroptera, Plecoptera, and Trichoptera in river ecosystems. Our findings thus indicate that the functional boundaries of river ecosystems can extend to aerosphere. Our article aims to provide new perspectives for re-evaluating conservation strategies for riverine ecosystems, including in relation to the dispersal ecology of aquatic insects and the fragmentation of ‘aerial corridors’ by artificial structures such as dams.

While use of the emergent adult stage of aquatic insects as stream bioindicators has lagged well behind that of the benthic stage, adult insects of large and diverse taxa such as Trichoptera have great potential for indicating stream conditions. To explore their associations with stream variables, nearly 500,000 adult caddisfly specimens were collected from 798 ultraviolet blacklight samples throughout the northcentral United States. From an original pool of 11 stream characteristic variables, a non-metric multidimensional scaling ordination determined four that were strongly associated with adult caddisfly assemblages: (1) mean summer stream temperature, (2) stream gradient, (3) base flow as a percentage of total flow, and (4) percentage of intact upstream terrestrial habitat. Association values for 209 common species, 60 common genera, and 17 common families from the region are herein presented based on weighted mean specimen abundance and coefficient of variation for each of the four determined variables. While validation of these presented association values using other datasets is necessary to confirm their general utility, this work represents a first step in using adult caddisflies to indicate both natural and anthropogenic stream conditions.

Preserved samples of benthic macroinvertebrates may be useful for examining spatiotemporal changes in aquatic food webs. However, archived samples preserved in ethanol may have altered isotopic values because of the effects of ethanol on tissue composition. Two mayfly species, Epeorus vitreus (Walker, 1853) (Ephemeroptera: Heptageniidae) and Acentrella turbida (McDunnough, 1924) (Ephemeroptera: Baetidae) were collected from Wills Creek and the Savage River, Maryland, USA. We measured five replicates for whole body %carbon, %nitrogen, δ 13C, and δ 15N at Day 0 (fresh, not stored in ethanol) and then two weeks, one month, three months, six months, nine months, and 12 months following storage in 95% ethanol. Within one week, ethanol preservation typically caused δ 13C values to increase by 0.5–1‰; whereas, changes in δ 15N values were < 1‰ or absent. Changes in δ 13C occurred coincident with declines in tissue C:N ratios and % C, likely due to leaching of lipids from tissues. These results indicate that long-term ethanol preservation is unlikely to bias δ 15N values of archived stream invertebrates, supporting the use of preserved specimens in future studies of changing nitrogen dynamics through time. Furthermore, results do not support the use of C:N as an index of lipid-storage in ethanol-preserved macroinvertebrates.

The genus Notonecta Linnaeus, 1758 includes 65 species worldwide. However, in India, only three species of the genus, N. viridis Delcourt, 1909, N. montandoni Kirkaldy, 1897 and N. glauca (Linnaeus, 1758), have been so far known. In this article, an additional Notonecta species, N. violacea Kirkaldy, 1897, collected in the Anjaw District of Arunachal Pradesh, is recorded for the first time from India. Description of the species morphology including its morphometric characteristics and illustrations of the male genitalia is provided.

A new nemourid species of the stonefly genus Sphaeronemura Shimizu and Sivec, 2001, S. xulongcheni Li, Yang, and Li, sp. n., is described from China and compared to its most similar congeners. The new species represents the first record of the genus from Hubei Province of China. Sphaeronemoura siveci Murányi and Li, 2013 is recorded for the first time from China.http://zoobank.org/urn:lsid:zoobank.org:pub:071B002F-86B0-4DAD-AEA9-1D0767829954

This study assessed various anatomical parameters of exuviae of three distinct populations of Aeshna juncea (Linnaeus, 1758) collected in Iran, the Netherlands and France. Fifty specimens (25 males, 25 females) from each country were analysed in detail. We measured 20 morphological traits for females and 19 traits for males. We found out that body length, left foreleg, left forewing sheath, left hindwing sheath, length of cercus, epiproct, epiproct spine, paraprocts and length of abdominal spines were larger in specimens originating from Iran compared to specimens collected in the studied areas of France and the Netherlands. In contrast, width of head and minimal width of prementum were larger in specimens from the Netherlands. According to our results, the measured morphological parameters indicated a greater similarity between the specimens found in France and the Netherlands compared to the specimens recorded in Iran. The presented data might be useful for future comparison of other populations of A. juncea throughout Eurasia.

The present study reports Ranatra cardamomensis Zettel, Phauk, Kheam, and Freitag, 2017 for the first time from India. This species was collected from the Eastern Ghats of Andhra Pradesh State and from Maharashtra. Taxonomic characteristics, specimen photographs and distribution range of the species are provided. With the present record, 14 species of Ranatra Fabricius, 1790 are now known from India.

To investigate how four species of Cybister Curtis, 1827 and one species of Hydaticus Leach, 1817 (Coleoptera: Dytiscidae) detect food, insects were provided with dried sardines using traps made by a three-dimensional printer. More than 83% of the beetles found the sardine hidden in the trap. When the two traps were set in an aquarium—one contained a dried sardine before extraction with boiled water, and another contained a dried sardine after extraction—more than 90% of beetles were caught in the trap with the sardine before extraction. In contrast, less than 3% of beetles entered the trap with the sardine after extraction. No feeding preference was found between the sardines before and after extraction. A microwave Doppler radar was used to quantitatively detect the behaviour using broth extracted from the sardines, and the broth enhanced the food-searching activity. These results suggest that these beetles use smell to find food, and their searching activities are induced by smell.