A Revision of the Leafhopper Genus Xyphon (Hemiptera: Cicadellidae)



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The leafhopper genus Xyphon, included in the sharpshooters, is a widely distributed group of insects whose species are vectors for various plant diseases. Xyphon has historically contained up to 9 species. These species have been poorly delimited in the past and their identification has been difficult using published keys. The genus is revised here based on a new species level phylogenetic assessment that incorporates both morphological and molecular data. The genus Xyphon was erected to contain leafhoppers that possessed a reticulated forewing apex but lacked both a median sulcus on the crown and a carinate anterolateral crown-face margin both of which are present in the closely related genus Draeculacephala. Young (1977) revised most of the genera included in Xyphon's containing subfamily. He did not attempt a revision of Carneocephala (the genus that formerly contained most Xyphon species), but noted the need for a revision of its species. This revision of the genus Xyphon is based on the examination of approximately 8,000 specimens and includes a phylogenetic analysis of the genus that includes data from one gene (NDI) and 47 morphological characters. A generalized model of each preliminary taxonomic unit was used to test the monophyly of each species. These tests resulted in the synonomization of 4 former species: Xyphon gillettei to include X. balli; and X. reticulatum to include X. diductum, X. dyeri, and X. sagittiferum. Parsimony and Bayesian techniques were used to infer relationships among species. These analyses resulted in almost identical tree topologies. In all analyses Xyphon was monophyletic and Draeculacephala was its sister genus although clade support for the genus was generally low. The analyses found that X. flaviceps and X. fulgidum form a basal clade within Xyphon, above which X. gillettei and X. n. sp. 1 (new species 1) form a clade that is sister to a third clade containing X. triguttatum, X. nudum, and X. reticulatum.