Taxonomic study on the genus Stenochironomus Kieffer from the Baishanzu Nature Reserve, China (Diptera, Chironomidae)

During the summer of July to September 2020, a biodiversity survey on Chironomidae of Baishanzu Nature Reserve, China was made. In total, five Stenochironomus taxa/species were discovered, of which two belong to undescribed species and one (S. okialbus Sasa, 1990) is reported for the first time from China. The male adults of two new species are described and illustrated. Stenochironomus annulus Song & Qi sp. nov. is distinguished in having a wing with two dark spots restricted to the fork area of FCu and RM, the mid- and hind-femur each with a brown annulus, and the inferior volsella with two setae and one strong terminal spine. Stenochironomus baishanzuensis Song & Qi sp. nov. is distinguished by a combination of characters: a single dark spot on the middle part of the wing, fore legs brown to dark brown except for the basal 3/4 of femur, and the inferior volsella with four long setae and one stout terminal spine. The neighbour-joining tree based on public COI barcodes formed distinct clades with clear support for the new species. An updated key to known male adults of Stenochironomus from China is also provided.