Abstract
Spider mite fauna of the genus Oligonychus Berlese (Acari: Prostigmata: Tetranychidae) was comprehensively explored from natural and cultivated vegetation in Saudi Arabia (SA), during the years 2018 to 2020. One new species, Oligonychus washingtoniae sp. nov., and three new records, O. coniferarum (McGregor, 1950), O. dactyloniSmiley & Baker, 1995, and O. tylusBaker & Pritchard, 1960, are reported for the first time from SA. The new species, O. washingtoniae sp. nov. is described and illustrated from Washingtonia filifera (Lindl.) H.Wendl. (Arecaceae). The species O. dactyloni, and O. tylus are re-described, which were briefly described previously.