Browsing by Author "Lewis L. Deitz, Committee Chair"

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Phylogeny and Systematics of the Leafhopper Subfamily Ledrinae (Hemiptera: Cicadellidae)
(2006-12-06) Jones, Joshua Raymond; Brian Wiegmann, Committee Co-Chair; Lewis L. Deitz, Committee Chair; Sterling Southern, Committee Member
Ledrinae represent a relatively small subfamily within the very large and diverse leafhopper family Cicadellidae. Prior to this study, the subfamily contained approximately 450 species in 5 tribes and 73 genera distributed worldwide, but primarily in Australia, Africa, and the Indomalayan region. Several authors have suggested Ledrinae are not monophyletic, and recent studies based on molecular and morphological data have called the existing classification into question. The goals of this study were to collect and analyze morphological data under rigorous phylogenetic criteria in order to test the monophyly of Ledrinae, provide robust definitions for the subfamily and its tribes, and provide a phylogenetic framework for understanding relationships among these leafhoppers. New phylogenetic hypotheses are presented here regarding the monophyly of Ledrinae and its included tribes. A total of 235 morphological characters were coded for 60 species from 31 genera in the tribes Ledrini and Petalocephalini, 5 species from the tribes Stenocotini, Thymbrini, and Xerophloeini, and 10 species selected as outgroups from various other cicadellid subfamilies. Data were analyzed in PAUP* and resulted in a single completely resolved topology with many well-supported nodes. Ledrinae, as previously defined, was found to be polyphyletic with respect to Stenocotini, Thymbrini, and various ledrine genera, which were placed with the outgroup taxa. Stenocotini and Thymbrini were placed with Tartessinae, agreeing with results of other recent studies. Rubria, Hespenedra, and the Afrorubria genus group formed independent lineages within Ledrinae. Xerophloeini was placed as a basal lineage within Ledrinae closely associated with the Afrorubria group. Ledrini and Petalocephalini, as previously defined, did not form monophyletic lineages, but were randomly interspersed with respect to one another. Stenocotini and Thymbrini are here removed to the subfamily Tartessinae, and Petalocephalini is made a synonym of Ledrini. Three new tribes are described within Ledrinae. Taxa placed outside of Ledrinae in this analysis are removed to other subfamilies or considered unplaced within Cicadellidae. This newly revised classification strengthens hypotheses that the Ledrinae are a very old group within Cicadellidae. As here defined, the subfamily includes five tribes with a total of 37 genera.
Phylogeny and Systematics of the Treehopper Subfamily Centrotinae (Insecta: Hemiptera: Membracidae)
(2004-04-07) Wallace, Matthew Spaulding; Lewis L. Deitz, Committee Chair
The subfamily Centrotinae is the largest and only cosmopolitan subfamily within the treehopper family Membracidae (Insecta: Hemiptera: Membracidae). As the first comprehensive morphological study of the subfamily, this work includes: (a) phylogenetic analyses, (b) illustrated taxonomic keys and descriptions for identifying 23 tribes (6 new) and 2 unplaced genera, (c) new synonymies (1 generic, 11 tribal, 1 subfamilial), (d) a new lectotype designation, and (e) 5 new combinations. Of 216 genera here included in the subfamily, 207 are placed in tribes, 2 are unplaced but have known affinities, and 7 are too poorly known for placement. One genus formerly placed in the Centrotinae is placed as Membracidae, incertae sedis. Phylogenetic analyses were performed based on 116 morphological characters from the head, thorax, and abdomen of both sexes. These analyses (1 overall analysis of 24 tribes and 8 analyses of the larger tribes) resulted in a single most parsimonious tree showing a basal clade with one New World tribe, followed by two major clades--each with New World components basally followed by Old World components. These analyses demonstrated that the most recent classifications included numerous para- or polyphyletic tribes. Consequently, the tribal placements of 108 genera are changed so that all tribes are monophyletic. As here defined, the subfamily Centrotinae is also a monophyletic group supported by the synapomorphy of the presence of abdominal inornate pits, each with a lateral seta. Characters important in elucidating tribal relationships include features of: the male and female genitalia, the fore- and hind wings, the scutellum, leg chaetotaxy; and abdominal characteristics using scanning electron microscopy. Each tribal diagnosis and description is followed by notes on ecology and distribution, a list of included genera, specimens examined, and discussions of phylogeny and morphological characters. For most genera, the head, pronotum, wings, legs, male and female genitalia, and abdominal fine structure are illustrated. Based on the phylogeny inferred herein, centrotines originated in the New World (6 tribes) and subsequently invaded the Old World twice, possibly via the Bering Land Bridge, which would have facilitated western invasions from North America to the Palearctic and Indomalayan Regions in the early Tertiary. Subsequently, major radiations (17 tribes) occurred within the Old World. While a few centrotine tribes are widely distributed, many occur primarily in one or two major zoogeographic regions. No tribe occurs in both the Old World and New. The distinctive faunas of the Afrotropical, Indomalayan, Australian, and Caribbean Regions are especially notable. Centrotines have exploited 105 plant families. Dominant among these are the Leguminosae, Compositae, Solanaceae, and Euphorbiaceae. At least 11 of the 23 centrotine tribes include genera that are attended by ants, which feed on the honeydew secreted by treehoppers. The distribution of these ecological and behavioral traits, as well as chromosome numbers, are mapped on the tribal phylogeny. Included are 186 figures (1500 individual illustrations and photographs) and 17 tables.