Three new species of the genus Ischnothyreus Simon, 1893 and the discovery of the male of I.linzhiensis Hu, 2001 from Tibet, China (Araneae, Oonopidae)

Four species of the genus Ischnothyreus Simon, 1893 from Tibet, China are recognised, including three new species, I.caoqiisp. nov. (female), I.metoksp. nov. (female), and I.pomesp. nov. (male and female). Males of Ischnothyreuslinzhiensis Hu, 2001 are discovered for the first time since its description. Descriptions, diagnoses, and photographs of the four species are provided.