The goblin spider genus Pescennina Simon has been known only from females of its type species from Venezuela, whereas the more recently described genus Marsupopaea Cooke has been known only from males taken in Colombia. Discovery of the missing sexes, in both cases, indicates that these spiders belong to the Scaphiella complex; males have dorsal abdominal scuta that are absent in females. The presence, in the males of both type species, of a terminal, coiled embolus that can be held in an excavated “pouch” at the anterior edge of the sternum and is matched by coiled anterior ducts in the female genitalia, suggests that these taxa are congeneric. Marsupopaea is therefore newly synonymized with Pescennina, and its type species, M. sturmi Cooke, is placed as a junior synonym of P. cupida (Keyserling). Species of Pescennina occur widely in North, Central, and South America; many are apparently ant mimics, with color patterns (and sometimes a constricted abdomen) that enhance their antlike appearance. Although most of the species seem to be ground dwelling, with the extremely narrow geographic ranges typical of goblin spiders, at least four species inhabit the forest canopy, and at least one of those species is much more widespread. Males of the type species, P. epularis Simon, and females of P. cupida (Keyserling) are described for the first time; 16 new species are described: P. iviei, P. gertschi, P. sumidero, and P. ibarrai from Mexico; P. murphyorum from Nicaragua and Costa Rica; P. viquezi from Costa Rica; P. laselva from Costa Rica and Panama; P. fusca from Panama; P. arborea from Panama, Colombia, and Ecuador; P. magdalena and P. sasaima from Colombia; P. orellana from Ecuador; P. piura and P. loreto from Peru; P. grismadoi from Bolivia; and P. otti from southern Brazil.