The genus Stenotarsus gen. nov. closely related to Aphonopelma Pocock, 1901 is established for South American species formerly desgnated as Eurypelma group A according to SIMON 1892 where metatarsus I containing many spines is as long as or not as long as tibia I. It differs from Aphonopelma by a procurved fovea (fig. 13), urticating hairs of type 1 and 3, a distally widened embolus (fig. 3) and spermathecae widely fused (fig. 19 - 21) with two little heads of different shape. S scissistylus is a medium-sized species. It's embolus appears deeply rutted (fig. 4) The relations to other species living in the Guyanas, North Brazil and Venezuela are discussed.