A discussion of morphological differences within Claassenia qingzanga Xiang, Huo & Du, 2022 (Plecoptera: Perlidae) based on molecular data and a redescription of C. magna Wu, 1948

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.