Two poorly known species of Kamimuria Klapálek, 1907, K. simplex (Chu, 1929) and K. tienmushanensis Wu, 1938, are redescribed and newly recorded for Mt. Wuyi, Fujian. Kamimuria cheni Wu, 1948 and K. crassispina Wu, 1948 are removed from the species list of Fujian. The morphological variability of K. tienmushanensis from different locations is also discussed in this paper.

Mitochondrial genomes of three stoneflies, e.g., Claassenia magna Wu, 1948, Claassenia sp. 2 and Claassenia xucheni Chen, 2019 were sequenced in this study with 15,774, 15,777 and 15,746 bp in length, respectively. Each mitogenome contained 37 genes including 22 tRNAs, two ribosomal RNAs, 13 protein-coding genes (PCGs), and a noncoding control region (CR). In general, standard ATN start and TAN termination codons were evident in the PCGs. Although the dihydrouridine arm was absent in trnSer, the remaining 21 tRNAs displayed the characteristic cloverleaf secondary structure. Stem-loop structures were identified in the CRs of all three mitogenomes, but tandem repeats were only apparent in Claassenia xucheni. The mitogenomes of three Claassenia species were analyzed and compared with mitogenomes in 21 other stoneflies from the Perlidae and three Euholognatha species (Rhopalopsole bulbifera, Capnia zijinshana and Amphinemura longispina) as outgroups. Phylogenetic analyses using maximum likelihood and Bayesian inference. Phylogenetic analysis supported that Claassenia was recovered as the sister group of other Perlinae and Claassenia+Perlinae emerged from the paraphyletic Acroneuriinae. The final results supported that Claassenia was classified into subfamily Perlinae and proposed Claassenia represent a transitional group of the subfamilies Acroneuriinae and Perlinae. This study provided new molecular evidence for exploring the debatable taxonomic position of the genus Claassenia in Perlidae.

Three new species of Sinacroneuria Yang & Yang, 1995, Sinacroneuria parallela Xiang & Du, sp. nov., Sinacroneuria complana Xiang & Du, sp. nov. and Sinacroneuria longiprojecta Du & Huo sp. nov., from Zhejiang Province of southeastern China are described and illustrated. A list and provisional key to Sinacroneuria males of Zhejiang Province are also presented.

Currently, information on the biology of Plecoptera from China is scarce, particularly on mating behavior. In this paper, the existence of mating mistakes (erroneous mating attempts) involving 13 Chinese stonefly species (belonging to nine genera and three families) is reported. These erroneous mating behaviors can be included into three different categories: mating attempts between conspecific males (including the formation of erroneous mating balls), mating attempts between different taxa (including displacement attempts during copulation), and mating-related behaviors with non-living objects. From these behaviors, some aspects of stoneflies during mating, such as the physical competition between males, the sensorial mechanisms implied in triggering a mating behavior, the conditions favoring the mating mistakes, and the possible consequences of interspecific mating in the hybrid production, are discussed.

A new species, Claassenia qingzanga Xiang, Huo & Du, sp. nov. is described from Tibet and Qinghai Province of western China, this is the first record of Claassenia in Qinghai-Tibet Plateau. Males of the new species are brachypterous, the apex of the aedeagus with tiny spines dorsally and with dense protrusion laterally. The new species is compared to all regional Claassenia.

In the genus Claassenia Wu, 1934, the sensilla basiconica patch is an important identification characteristic, yet there are few studies that have investigated this trait. Recently, we found that tergum 8 of males of Claassenia qingzanga Xiang, Huo & Du, 2021 collected from the Qinghai Province of China have a small, scattered basiconica patch, while the specimens collected from the Tibet Autonomous Region of China lack this characteristic. To verify their genetic relationship, we sequenced the mitochondrial cytochrome C oxidase subunit I gene of C. qingzanga collected from Tibet and Qinghai provinces. Phylogenetic analyses using Maximum Likelihood and Bayesian Inference methods, the two forms of C. qingzanga grouped together with strong nodal support and separate from the other Claassenia species analyzed. Genetic distance among these two forms of C. qingzanga is only about 1%. The molecular analyses confirmed that specimens with morphological differences are indeed the same species. A discussion of morphological differences within C. qingzanga and its genetic relationships are presented based on molecular data. Additionally, Claassenia magna Wu, 1948 is redescribed based on recent specimens.