Revision of the New World leafhopper tribe Faltalini (Hemiptera: Cicadellidae: Deltocephalinae) and the evolution of brachyptery

The taxonomy of the deltocephaline leafhopper tribe Faltalini (13 genera, 63 species) is revised. A key to all genera and keys to species for each genus are provided. All genera are described and at least one species of each genus is illustrated including images of the habitus, male and female genitalia, and scanning electron microscope (SEM) images of the head, face, and other characters. The new genera Dietrichana n.gen. [type species D. pampas n. sp.] and Paraclorindaia n.gen. [type species P. pinguis n. sp.] are described and the following 36 new species are described: Ackbaria jujuyensis n. sp. [Argentina], A. ojosverdes n. sp. [Argentina], Aequcephalus laplata n. sp. [Chile], Bonamus jussaral n. sp. [Brazil], Clorindaia obrienorum n. sp. [Uruguay], C. otamendi n. sp. [Argentina], Dietrichana pampas n. sp. [Argentina], Faltala catalanoae n. sp. [Argentina, Uruguay], F. paradellae n. sp. [Argentina], F. viscacha n. sp. [Argentina, Uruguay], Hecullus mexicanus n. sp. [Mexico], Kramerana saltensis n. sp. [Argentina], Paraclorindaia pinguis n. sp. [Argentina, Uruguay], P. vesperis n. sp. [Argentina], Tenucephalus admirabilis n. sp. [Argentina], T. bartletti n. sp. [Peru], T. brevilamina n. sp. [Argentina], T. cerrado n. sp. [Brazil], T. ecuadorensis n. sp. [Ecuador], T. flagellifer n. sp. [Peru], T. heppneri n. sp. [Peru], T. iguazu n. sp. [Argentina], T. interstinctus n. sp. [Peru], T. johnsoni n. sp. [Brazil], T. lingulatus n. sp. [Bolivia, Peru], T. manuensis n. sp. [Peru], T. misiones n. sp. [Argentina], T. musettiae n. sp. [Brazil], T. nielsoni n. sp. [Brazil], T. novafriburgo n. sp. [Brazil], T. parana n. sp. [Argentina], T. spectabilis n. sp. [Peru], T. takiyae n. sp. [Brazil, Peru], T. umbrinus n. sp. [Brazil], T. viperinus n. sp. [Argentina], and Virganana danasensis n. sp. [Ecuador]. The new combinations Paraclorindaia brasileira (Zahniser) n.comb. [transferred from Clorindaia] and Tenucephalus amabilis (Linnavuori & Heller) n.comb. [transferred from Bonamus] are recognized. A phylogenetic analysis based on 51 morphological characters scored for 42 taxa including two outgroup taxa was performed. The resulting phylogeny resolved Faltalini as monophyletic, but the tribe remains difficult to diagnose because it encompasses a large amount of morphological diversity in characters traditionally used to define tribes of Deltocephalinae including head morphology, wing length and venation, and male genitalia. Despite this diversity, members of the tribe share the following characters: 1) phragma of male genital capsule partly developed into sclerotized plates or setose bulbous lobes (exception: Acrolithus); 2) first valvula shape relatively straight; 3) first valvula dorsal sculpturing separated from dorsal margin by unsculptured band; 4) first valvula dorsal sculpturing pattern maculose, with maculae separate or only slightly overlapping, or granulose; 5) first valvula with distinctly delimited ventral sculptured area; and 6) second valvula without dorsal teeth. Two major clades within the tribe were resolved and strongly supported, consisting of (Bonamus, Tenucephalus) and (Hecalocorica, (Hecullus, (Acrolithus, (Ackbaria, (Aequcephalus, Dietrichana, Virganana, Clorindaia, Faltala (Kramerana, Paraclorindaia)))))). A stepwise evolution of brachyptery in the latter clade is suggested by the phylogeny, beginning with evolution of subbrachypterous females in Hecullus and Acrolithus and culminating in completely brachypterous males and females in the monophyletic “Faltala group” of eight genera. It is hypothesized that a transition from an ancestral forested habitat to an open or grassland habitat facilitated the evolution of brachyptery. The hindwings and associated thoracic structures of eight species of Faltalini and three other Deltocephalinae were imaged with SEM. Brachyptery in Cicadellidae and other insects are briefly reviewed and discussed considering the hypothesis proposed here.