Taxonomic revision and phylogenetic analysis of the sharpshooter genus Balacha Melichar (Hemiptera : Cicadellidae : Cicadellini)

• Author(s): Mejdalani, G.; Takiya, Daniela;
• Abstract: Balacha currently includes six valid described species and B. caparao sp. nov., here described from Minas Gerais State, Brazil. The new taxon differs from other Balacha species in the ventrally inflated preapical aedeagal area and oblique bases of the ovipositor first valvulae. New records are as follows: B. decorata from Paraguay and Minas Gerais State (Brazil); B. distincta from Brazil; B. melanocephala from Montevideo Department (Uruguay) and Buenos Aires and Distrito Federal provinces (Argentina); and B. similis from Rio de Janeiro and Minas Gerais states (Brazil). Colombia is considered a dubious record for the genus. Phylogenetic relationships among Balacha species are examined based on a matrix of eighteen terminal taxa and sixty-seven morphological characters. Balacha may be defined by the following synapomorphies: crownfrons transition approximately acute, crown anteriorly produced and with anterior margin subangulate, flattened pronotum continuing contour of head and mesonotum in lateral view, and teeth of second valvulae of ovipositor with anterior dorsal projection. The genus comprises two major lineages: the red Balacha clade (B. lepida (B. distincta+B. rubripennis)), and the black Balacha clade (B. caparao (B. decorata (B. melanocephala+B. similis))). Despite the scarcity of data on host plant usage of outgroup taxa (probably generalists on Lamiaceae, Lauraceae, and Asteraceae), we believe that the shift to feeding on Eryngium (Apiaceae) occurred in the ancestor of all recent Balacha species. Their small size and depressed body appear to be adaptations to living inside the rosette disposed leaves, and they seem to be restriced to this microhabitat. Balacha and their Eryngium hosts occur in grasslands in temperate South America, but at lower latitudes in Brazil they are isolated in alpine meadows on peaks of the southeast highlands. Dispersal between such areas through the lowland humid Atlantic forest in recent times would be difficult, thus the ancestor of Balacha was probably distributed in southeast South America before the uplift of the mountain ranges, during the late Eocene or Oligocene. This event may have triggered speciation of some lineages of the genus by vicariance.
• Publication Date: Jan 2004
• Journal: Systematic Entomology