Species of the family Stigmaeidae (Acari: Trombidiformes), living in soil and on plants in various parts of the world, are usually predators of other mites and a few prey on tree-associated arthropods or parasitize flies (Swift 1987; Fan and Zhang 2005). It is the largest family within the superfamily Raphignathoidea, and was established by Oudemans (1931). This family includes about 600 species in 33 valid genera (Fan et al. 2016; Doğan et al. 2017; Akyol 2019; Doğan, 2019; Khaustov 2019). The genus Stigmaeus is one of the largest and most diverse genera in the family, containing 143 valid species up to now and so far 43 species of this genus were recorded or described from Iran (Khanjani et al. 2015; Fan et al. 2016; Khaustov et al. 2017; Da-Costa et al. 2018; Akyol 2019; Majidi et al. 2019). During 2018, the fauna of Raphignathoidea mites in Arasbaran Forests was studied. Mites were extracted from samples using a Berlese-Tullgren funnel and they were cleared in lactophenol fluid for 2–3 days and finally mounted in Hoyer's medium. Among collected species of the genus Stigmaeus, S. diversus was identified. This species originally was described from Uzbekistan by Barilo (1987), and has been reported only from that country. In this study, we are reporting it from Iran for the first time. Measurements are given in micrometers. Genus Stigmaeus Koch, 1836 Type species: Stigmaeus cruentus Koch, 1836. Stigmaeus diversus Barilo, 1987 (Fig. 1) Redescription of
