Phylogeny of the major lineages of Membracoidea (Insecta: Hemiptera: Cicadomorpha) based on 28S rDNA sequences

Analysis of sequences from a 3.5-kb region of the nuclear ribosomal 28S DNA gene spanning divergent domains D2-D10 supports the hypothesis, based on fossil, biogeographic, and behavioral evidence, that treehoppers (Aetalionidae and Membracidae) are derived from leafhoppers (Cicadellidae). Maximum-parsimony analysis indicated that treehoppers are the sister group of a lineage comprising the currently recognized cicadellid subfamilies Agalliinae, Megophthalminae, Adelungiinae, and Ulopinae. Based on this phylogenetic estimate, the derivation of treehoppers approximately coincided with shifts in physiology and behavior, including loss of brochosome production and a reversal from active, jumping nymphs to sessile, nonjumping nymphs. Myerslopiidae, traditionally placed as a tribe of the cicadellid subfamily Ulopinae, represented a basal lineage distinct from other extant membracoids. The analysis recovered a large leafhopper lineage comprising a polyphyletic Deltocephalinae (sensu stricto) and its apparent derivatives Koebeliinae, Eupelicinae (polyphyletic), Selenocephalinae, and Penthimiinae. Clades comprising Macropsinae, Neocoelidiinae, Scarinae, Iassinae, Coelidiinae, Eurymelinae + Idiocerinae, Evacanthini + Pagaroniini, Aphrodinae + Ledrinae (in part), Stenocotini + Tartessinae, and Cicadellini + Proconiini were also recovered with moderate to high branch support. Cicadellinae (sensu lato), Ledrinae, Typhlocybinae, and Xestocephalinae were consistently polyphyletic on the most-parsimonious topologies, but constraining these groups to be monophyletic did not significantly increase the length of the cladograms. Relationships among the major lineages received low branch support, suggesting that more data are needed to provide a robust phylogenetic estimate.

Secretion of brochosomes during the ontogenesis of a leafhopper, Oncometopia orbona (F.) (Insecta, Homoptera, Cicadellidae)

Secretion of brochosomes, intricately structured symmetrical protein-lipid particles produced in the specialized Malpighian tubules of the Cicadellidae, was studied during the ontogenesis of Oncometopia orbona (F.). Unlike most other cicadellids, O. orbona displays sexual dimorphism in the production of brochosomes. The Malpighian tubule secretory cells of nymphs, males and young females produce spherical brochosomes of 0.3-1.4 microm in diameter, extruded after molts through the hindgut and spread across the integument as a coating. In females with developing eggs the same cells switch to producing rod-like brochosomes of 3.5-11.0 microm in length, which are used to powder the oviposition sites. The transition involves a dramatic change in morphogenesis of the secretory particles. Both types of brochosomes derive from homogenous condensing Golgi granules and acquire their definitive structure as a result of growth, differentiation of the contents into a wall and a core, and development of a lattice of surface invaginations. Final stages of this process take place in Golgi-derived vacuoles. In the development of rod-like brochosomes the condensing granules coalesce into masses several times larger than nascent spherical type. These giant granules flatten, then become doughnut-shaped and finally break open into a pair of linear particles. Whether the chemical composition differs between the two types of brochosomes remains unknown.