Multiple cave invasions by species of the planthopper genus Oliarus in Hawaii (Homoptera : Fulgoroidea : Cixiidae)

Although geologically young, the Hawaiian Islands harbour a rich and remark ably diverse fauna of terrestrial troglobites: more than 70 cave species ar e known from Kauai, Oahu, Molokai, East Maui, and Hawaii Island. Among the more speciose groups that have invaded the subterranean biome are the plant hoppers (Homoptera Cixiidae) of the genus Oliarus. Five new obligately cave rnicolous (troglobitic) Oliarus species which differ in their degree of tro glomorphy and male genital structures, are described from lava tubes on the Hawaiian Islands: O. lorettae sp. nov, and O, makaiki sp. nov, from Hawaii Island, O. gagnei sp, nov. and O. waikau sp. nov. from Maui Island, and O. kalaupapae sp. nov. from Molokai Island. Short diagnoses of the two troglo bitic species already known, O. polyphemus Fennah, 1973 from Hawaii Island and O. priola Fennah, 1973 from Maui are provided. Notes on the ecology and distribution of all cavernicolous species are given, Morphological evidenc e suggests that each of the seven cavernicolous Oliarus species from Hawaii represents a separate, independent adaptive shift to underground environme nts. Potential relationships to the extant epigean species are discussed. ( C) 1999 The Linnean Society of London.