First record of the genus Trilacuna Tong & Li, 2007 (Araneae, Oonopidae) from Xizang, China, with descriptions of three new species and one newly recorded species

Four species of the genus Trilacuna Tong & Li, 2007 from Xizang, China are recognized, including three new species and one newly recorded species: T.bangla Grismado & Ramírez, 2014, T.mainling Tong & Li, sp. nov. (♂♀), T.metok Tong & Li, sp. nov. (♂♀) and T.zayu Tong & Li, sp. nov. (♂♀). Descriptions, diagnoses and photomicroscopy images are provided.