Five new species of the genus Grouvellinus Champion, 1923 from Guizhou Province, China (Coleoptera, Elmidae)

The genus <i>Grouvellinus</i> Champion, 1923 comprises 60 described species distributed across the Oriental and Palearctic regions. Species diversity is very high in mainland China, with 28 recorded species. Here, the results of the aquatic beetle survey in Guizhou Province are presented; they began in 2021, when we collected more than 5000 specimens of riffle beetle. All specimens come from small ravine streams where inhabited submerged stones. Using morphological characters of adults such as body form and size, coloration, elytral, pronotal and ventral surface structures, and forms of male and female genitalia, five new species were discovered and are described: <i>Grouvellinusloong</i> <b>sp. nov.</b>, <i>G.buyi</i> <b>sp. nov.</b>, <i>G.wangmoensis</i> <b>sp. nov.</b>, <i>G.lihaitaoi</i> <b>sp. nov.</b>, <i>G.muyinlini</i> <b>sp. nov.</b> The species descriptions contain illustrations of diagnostic characters and measurements of metric characters such as body length, pronotal length, pronotal width, elytral length and width, and head length and width. The females are, on average, larger and have only slight differences in external morphology compared to the males. The comparative diagnoses discuss characters of the new and already known species. The results show that the existing species diversity requires more detailed research focusing on larger areas of South China in the future.