We investigated the mating biology of the previously unstudied central European spider Leviellus thorelli (Ausserer 1871) by staging laboratory mating trials using males and females of varying mating histories. Our aim was to seek common themes in sexual behaviors of the sexually size-monomorphic “zygiellid” spiders with their putatively close relatives, araneids and nephilids, which are relatively well studied with respect to sexual biology. We found L. thorelli mating biology to more closely resemble that of sexually size-monomorphic araneids than that of dimorphic nephilids. Unlike in nephilids with sexually conflicted adaptations, we found no evidence for genital damage or plugging in Leviellus Wunderlich 2004, although we found rare cases of half-eunuchs. We suggest that the mating system of L. thorelli spiders is determined by short female sexual attractiveness, reduced receptivity after mating and/or intensive mate guarding.