The recent publication of the Metcalf catalogue of world Cicadelloidea (128) listed 4378 species, placed in 591 genera and 54 subgenera. These were assigned to the following 17 different families: Tettigellidae, Hylici dae, Gyponidae, Ledridae, Ulopidae, Evacanthidae, Nirvanidae, Aphrodidae, Hecalidae, Euscelidae, Coelidiidae, Eurymclidae, Macropsidae, Agalliidae, Iassidae, Idioceridae, and Cicadellidae. The catalogue includes all of the lit erature on the leafhoppers to 1942. Since that time at least 1200 additional species and 100 additional genera have been described. The world literature at the present time therefore covers some 5500 to 6000 species and probably 700 or more genera.Morphological characters have been used predominantly for the classifi cation of the leafhoppers, particularly the type, form, and venation of wings, structures of the head and crown, position of the ocelli, general shape of the body, and the genital structures of both sexes. The character of the structures of the male genital chamber, the styles, aedeagus, connective, plates, pygofer, and the apodemes on the anterior portion of the abdomen have been used especially for the separation of species. In most groups these characters are excellent for specific identification. In a few groups, Oncop sis Burmeister, for instance, they have proved to be of little or no value.
ISOLATED POPULATIONS, MUTANTS AND SPECIES CONCEPTSCertain species of leafhoppers such as Macrosteles fascifrons have a wide geographical range through different life zones extending from Mex ico and Puerto Rico to Alaska, from tropical to arctic habitats. As now rec ognized by taxonomists, this species is a complex of genetic mutants rang ing in size from 2.0 to 5.1 mm and occurring on a great variety of host plants. Economic and ecologic studies have revealed isolated popUlations of this species which were biologically, ecologically, or physiologically specific but could not be separated morphologically. Beirne (6), after a detailed study of all of the material in the genus Ma cyosteles, has affirmed that physiologic species and isolated ecologic popula tions undoubtedly exist and that the progeny of certain populations are sed entary, which would favor isolation. Severin (180) failed in his attempt to mate a long-winged form from the Montara Mountains of California with a short-winged form from the eastern United States. With the exception of the wing condition these were not different morphologically. The occur-179 6007 Annu. Rev. Entomol. 1971.16:179-210. Downloaded from www.annualreviews.org Access provided by Michigan State University Library on 02/07/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS