Leafhoppers (Cicadellidae)

======== INTRODUCTION ======================================================== Leafhoppers are one of the largest families of plant-feeding insects, currently comprising approximately 20,000 described species. Recent sampling in the tropics suggests that fewer than 10% of tropical species have been described. Leafhoppers feed by sucking the sap of vascular plants, and are found almost anywhere such plants occur, from tropical rainforests, to arctic tundra. Several leafhopper species are important agricultural pests. ======== RELATIONSHIPS ======================================================= Together with the three currently recognized families of treehoppers (Melizoderidae, Aetalionidae, Membracidae) and Myerslopiidae, Cicadellidae form a well supported monophyletic group (Membracoidea). Relationships among the major lineages of Membracoidea are not well understood, but based on available evidence, Myerslopiidae is sister to a clade comprising the other four families. The monophyly of Melizoderidae + Aetalionidae + Membracidae is well supported by morphological evidence, but the monophyly of Cicadellidae is doubtful. Recent analyses of combined morphological and 28S rDNA sequence data suggest that Cicadellidae is paraphyletic with respect to the three treehopper families and that the sister group of treehoppers is a clade comprising the leafhopper subfamilies Megophthalminae (s.l.) and Ulopinae. ======== DIAGNOSIS =========================================================== Cicadellidae are distinguished from other families of superfamily Membracoidea by the following combination of features: (1) pronotum not extended over scutellum, usually not extended to scutellar suture (exceptions Signoretiinae and some Ulopinae), leaving part of mesonotum exposed; (2) forewing with veins R and M forming common stem distad of their separation from vein Cu; (3) front femur usually with differentiated groups of setae; (4) hind tibia nearly always with four well differentiated rows of enlarged longitudinal setae; (5) brochosomes (minute granules produced by Malpighian tubules) present on integument.>