Systematics of Pilielmis Hinton, 1971 (Coleoptera: Dryopoidea: Elmidae).

Pilielmis is a small genus of Neotropical Elmidae found in the Amazon basin and French Guiana, with distribution in five countries: Brazil, Colombia, French Guiana, Peru, and Venezuela. Currently, seven species of Pilielmis are known, six of which were described in the original description of the genus by Hinton (1971), and the most recent one was described by Polizei & Barclay (2019). In this paper, we review the genus Pilielmis based on the analysis of type-specimens and material collected in different regions of northern South America. A phylogenetic study was performed to hypothesize the relationship between all species of Pilielmis and to test the monophyly of this genus. For this purpose, 42 morphological characters of adults were investigated, among them some structures that were not illustrated and described in the original descriptions. As result, all seven previously known species were redescribed with standardized morphological information. Three new species were discovered in the examined material: Pilielmis baniwa sp. nov., Pilielmis muricula sp. nov., Pilielmis nheengatu sp. nov. A key for identification of the adults of Pilielmis is proposed and new records for Suriname, Peru, and some Brazilian states are presented. The phylogenetic analysis corroborated the monophyly of Pilielmis and presented phylogenetic information from characteristics not used before in the taxonomy of the genus, such as mouth parts and female ovipositor.

Do microplastics and climate change negatively affect shredder invertebrates from an amazon stream? An ecosystem functioning perspective.

Pollution and climate change are among the main threats to the biodiversity of freshwater ecosystems in the 21st century. We experimentally tested the effects of microplastic and climate change (i.e., increase in temperature and CO2) on the survival and consumption by an Amazonian-stream shredder invertebrate. We tested three hypotheses. (1) Increased microplastic concentrations and climate change reduce shredder survival. We assumed that the combined stressors would increase toxic stress. (2) Increased concentrations of microplastics have negative effects on shredder food consumption. We assumed that blockage of the digestive tract by microplastics would lead to reduced ability to digest food. In addition, increased temperature and CO2 would lead to an increase in metabolic cost and reduced consumption. (3) The interaction between microplastics and climate change have greater negative effects on survival and consumption than either alone. We combined different concentrations of microplastic and climate change scenarios to simulate in real-time increases in temperature and CO2 forecast for 2100 for Amazonia. We found that both stressors had lethal effects, increasing mortality risk, but there was no interaction effect. Shredder consumption was negatively affected only by climate change. The interaction of microplastics and climate change on shredder consumption was dose-dependent and more intense in the extreme climate scenario, leading to reduced consumption. Our results indicate that microplastic and climate change may have strong effects on the consumption and/or survival of insect shredders in Amazonian streams. In addition, microplastic and climate change effects may affect not only populations but also ecosystem functioning (e.g., nutrient cycling). Integrative approaches to better understand and mitigate the effects of both stressors are necessary because plastic pollution and climate change co-occur in environments.