Epistrophe melanostoma and Epistrophe nitidicollis are very similar species. A good diagnostic character are the hairs on top of the scutellum (not the hairs at the base surrounding the scutellum!). These hairs are yellow in Epistrophe melanostoma, but black in Epistrophe nitidicollis. Another character that is constant in female Epistrophe melanostoma (at least in the Central European specimens that I have seen so far) is the little notch in the middle of the dark bands across the third and fourth tergite.