S. chaconi sp.n. is described and illustrated on the basis of I S and I $ (holotype 6: Venezuela, Bolivar, Auyan-Tepui, 1730 m. 1/7-II-1994; deposited at MIZA, Maracay). The new sp. resembles S. roraimae De Marmels, 1988, but differs from it in shape of superior caudal appendages and vulvar lamina. — A Pantepuyan form of Tramea binotata (Ramb., 1842) with exceptionally large hindwing basal spot is also brought on record. The known Venezuelan distribution of both spp. is mapped.