The genus Platyscelio Kieffer (Hymenoptera: Platygastridae, Scelioninae) is a widespread group in the Old World, found from West Africa to northern Queensland, Australia. The species concepts are revised and a key to world species is presented. The genus is comprised of 6 species, including 2 known species which are redescribed: Platyscelioafricanus Risbec (Benin, Cameroon, Central African Republic, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Kenya, Mozambique, Nigeria, Sierra Leone, South Africa, Tanzania, Togo, Uganda, Yemen, Zimbabwe); and Platysceliopulchricornis Kieffer (Australia, Bangladesh, China, India, Indonesia, Japan, Malaysia, Papua New Guinea, Philippines, Solomon Islands, Taiwan, Thailand, Vanuatu, Vietnam). Five species-group names are considered to be junior synonyms of Platysceliopulchricornis: Platyscelioabnormis Crawford syn. n., Platysceliodunensis Mukerjee syn. n., Platysceliomirabilis Dodd syn. n., Platysceliopunctatus Kieffer syn. n., and Platysceliowilcoxi Fullaway. The following species are hypothesized and described as new taxa: Platyscelioarcuatus Taekul & Johnson, sp. n. (Western Australia); Platysceliomysterium Taekul & Johnson, sp. n. (Zimbabwe, Botswana, South Africa); Platysceliomzantsi Taekul & Johnson, sp. n. (South Africa); and Platysceliostriga Taekul & Johnson, sp. n. (Western Australia).
BACKGROUND: The genus Encarsia Förster, 1878, which is the largest genus of the family Aphelinidae, contains 453 valid species worldwide. Most species of Encarsia with known biology are primary endoparasitoids of Aleyrodidae and Diaspididae.
NEW INFORMATION: Species of the Encarsialongifasciata-group from Malaysia and China are reviewed. This is the first record of this group from Malaysia. Two new species, E.borneensis Geng & Li sp. n. and E.pauroseta Geng & Li sp. n., are described and illustrated. Encarsialongifasciata is newly recorded from Malaysia (Borneo). An updated key to the longifasciata-group species (females) worldwide is provided.