Two new species of Nigrobaetis Kazlauskas (in Novikova & Kluge), 1987 are described from Southwest China: Nigrobaetis bilongus sp. nov. based on larval and imaginal materials which are reared from larvae; Nigrobaetis trialbus sp. nov. based on larval stage.

Siphlonurus dongxi Li & Tong, sp. nov. from Shangri-La City, Yunnan Province, China, is described based on egg, nymph, and winged stages. The new species is closely related to S. davidi (Navás, 1932), and can be distinguished by the colour of the imago, the forking point of MP, the penis, posterolateral spines of tergum IX of imagoes, and first abdominal terga nymph, as well as the structure of the egg. The new species and S. davidi have the same morphological and structural characteristics, such as the long cubital area with many intercalaries, cross veins between C, Sc, RA, and RSa1 surrounded with distinct pigments, the strong curvature of vein CuP in the forewing, the broad expansion of the hindwing, the membranous penis lobes fused without teeth, supporting the proposition of a new species complex, the Siphlonurus davidi group. The structures of the penis and the egg of the new species could help understand the origin and evolution of the genus Siphlonurus.

Notacanthella jinwu Li & Jacobus, sp. nov. is described based on egg, nymph, and winged stages from Dali Bai Autonomous Prefecture, Yunnan Province, China. The nymph of the new species is closely related to N. commodema (Allen, 1971), whose nymphs share a similar tuberculation of head, pronotum, and mesonotum. However, the nymph of our new species can be distinguished based on the structures of male sternum IX and abdominal tergal tubercles. In addition, the new species is distributed in subtropical high-altitude areas. The description of the male imago of the new species is the first certain one for the genus Notacanthella. Data associated with our new species allow for expanded discussion and diagnosis of Notacanthella and closely related genera. An identification key for nymphs of these groups is provided.

This study explores the impact of anthropogenic land use changes on the macroinvertebrate community structure in the streams of the Cangshan Mountains. Through field collections of macroinvertebrates, measurement of water environments, and delineation of riparian zone land use in eight streams, we analyzed the relationship between land use types, stream water environments, and macroinvertebrate diversities. The results demonstrate urban land use type and water temperature are the key environmental factors driving the differences in macroinvertebrate communities up-, mid-, and downstream. The disturbed streams had lower aquatic biodiversity than those in their natural state, showing a decrease in disturbance-sensitive aquatic insect taxa and a more similar community structure. In the natural woodland area, species distributions may be constrained by watershed segmentation and present more complex community characteristics.

Mountain freshwater ecosystems are threatened all over the world by a range of human-induced stresses, ensuing in a rapid loss of habitats and species diversity. Many macroinvertebrates are reactive to habitat disturbance, and mayflies (Ephemeroptera) are amongst the most sensitive groups. Despite they are susceptible to environmental deviation, knowledge concerning their species richness and diversity is still unknown in remote areas. The objectives of this study were to (1) investigate the mayfly species assemblage and community composition along different mountain streams and assess potential differences, and (2) identify the environmental variation and its influence on the structure of mayfly communities within such freshwater systems. We collected biological and environmental data from 35 sites situated along elevation gradients in the Baima Snow Mountain, northwest Yunnan, China. Multivariate analyses were performed on the environmental variables and the mayfly species composition, as well as on richness and diversity indices. We found that the community composition of mayflies was different across all three watercourses. Among the 18 Ephemeroptera taxa identified, Baetis sp. and Baetiella marginata were highly dominant, accounting for over 50% of the dissimilarity of each stream. In terms of species assemblages, almost all sites in the Yeri stream hosted good-quality habitats for several mayfly species, as reflected by the highest species richness. The Benzilan stream followed, whereas the Sharong stream showed relatively low mayfly assemblage. This variation was explained by the high environmental heterogeneity between the three watercourses. In particular, the RDA model revealed that among the different environmental factors analyzed, altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Moreover, the altitude alone explained 17.74% of the variation, and in-depth analysis confirmed its significant effect on diversity indices. Further research should focus on evaluating the scale of threats to this important group of insects in the mountain freshwater ecosystem, particularly the impact of human-induced disturbances such as land use/landcover alterations.

We investigated the life history of Drunella submontana Brodsky, 1930 Brodsky, K . (1930), ‘Zur Kenntnis der mittelasiatischen Ephemeropteren, I. (Imagines)’, Zoologische Jahrbücher Abteilung für Systematik, 59, 681–720. [Google Scholar] using the size-frequency method at four sites at different altitudes (from 590 m to 2180 m) in Shennongjia National Park, Central China. Monthly samples of larvae were taken over a two-year period (May 2015–April 2017). Drunella submontana was considered exhibit three overlapping life cycle types: univoltinism with a short egg stage, univoltinism with a long egg stage and semivoltinism. Under diverse climatic habitats in the river ecosystem in Shennongjia National Park, some physicochemical parameters (such as temperature, conductivity, salinity, total dissolved solids and pH) of water showed significantly differences, and the developmental time of D. submontana prolongated from low to high altitudes. High larva density and the short egg stage appeared in middle altitude.