Summary Euathlus vulpinus (Karsch, 1880) and E. latithorax (Strand, 1908) are very similar species which were distinguished only by the position of a digitiform projection on the spermathecal receptacles, situated proximally in E. latithorax and distally in E. vulpinus. The spermathecal morphology is additionally characterised by the sinusoidal anterior margin and nodular fundus. We found a female Euathlus specimen from Concepcion, Chile that shares the characteristics of both species. The left receptacle has a distal digitiform projection, while the right receptacle has a proximal digitiform projection, suggesting that the position of the digitiform projection could vary among individuals. For this reason, E. latithorax is considered a junior synonym of E. vulpinus. The digitiform projection on the spermathecal receptacles of E. vulpinus could be interpreted as an additional lobe, this condition (multilobular spermathecae) having previously been considered absent in the subfamily Theraphosinae and ancestral within Mygalomorphae.