Two new species of theridiid spiders are described from northern Iran: Episinus mikhailovi sp. n. (♂♀, Gilan and Mazandaran provinces) and Theridion arsia sp. n. (♀, Qazvin Province); the latter has a unique type of thread-like mating plug previously undocumented in the family. Furthermore, Enoplognatha submargarita Yaginuma & Zhu, 1992, stat. reval. is rediagnosed and removed from the synonymy of Enoplognatha margarita Yaginuma, 1964, and a unique line of fine perforations connecting the copulatory openings are newly documented for this species. Finally, the first records of E. margarita from Mongolia and E. submargarita from Kyrgyzstan are also presented.