Abstract
BACKGROUND: Ischnothyreus Simon, 1893 is one of the most speciose genera of Oonopidae, with 124 extant species mainly distributed in the Old World. Currently, 27 species are known in China. NEW INFORMATION: A new species, Ischnothyreusruyuanensis Tong, sp. n., is described from Guangdong Province, China. Morphological description and illustrations are provided.