The genus Butheolus Simon, 1882 is revised based on new material from Dhofar Province in Oman. B. gallagheri Vachon, 1980 is redescribed, and a related new species, B. harrisoni sp. n., is also described. The species B. anthracinus (Pocock, 1895) is redescribed and moved to a new genus Xenobuthus gen. n., that is differentiated from Butheolus by size, pedipalp finger dentition, setation, granulation and hemispermatophore structure, and a related new species, X. xanthus sp. n., is also described. Revised diagnoses are provided for the genus Butheolus, and for the species B. thalassinus Simon, 1882, and B. villosus Hendrixson, 2006, a key is given for the species examined in this study, and the status of other related species discussed.