Taxonomic revision and phylogeny of an endemic leafhopper genus Nesocerus (Hemiptera: Cicadellidae: Idiocerinae) from Madagascar

The Malagasy endemic genus Nesocerus Freytag & Knight, 1966 is reviewed. A key is provided for the 35 recognized species, of which 29 are described as new. Diagnoses and descriptions, along with illustration of both taxonomic characters and habitus, are provided for all new species and for holotypes of five previously described species. Nesocerus trimaculatus Freytag & Cwikla is redescribed and its habitus and aedeagus are illustrated. Phylogenetic analysis of 65 adult morphological characters supports the monophyly of the genus with strong branch support. Within Nesocerus, the analysis recovered two sister clades, one comprising species mostly distributed in the eastern rainforests of Madagascar, and the other including species mainly restricted to the dry western region of Madagascar. The analysis did not resolve the relationship of Nesocerus to other Idiocerini unambiguously, but some unique derived features of the forewing and male genitalia suggest that the closest relatives of Nesocerus may include taxa from south Asia and South America.