Taxonomic and phylogenetic revision of the Gelastocephalini (Hemiptera: Cixiidae)

Planthoppers of the family Cixiidae Spinola, 1839 are economically important owing to their ability to transmit phytoplasmas causing yellows-type diseases. The tribe Gelastocephalini Emeljanov, one of 16 tribes within the subfamily Cixiinae, has never been revised comprehensively. Twenty new genera (Aubirestus, Balyadimetopia, Barbonia, Candicarina, Corylonga, Fletcherolus, Gelastocaledonia, Gurrundus, Guttala, Hartliebia, Holgus, Larivierea, Lipsia, Melanoclypeus, Novotarberus, Payastylus, Rokebia, Schuerrera, Wernindia, Yarnikada) and 50 new species ( Aubirestus semicirculatus, Balyadimetopia frederi, B. krahalla, B. marci, Barbonia spectabilis, Candicarina geroldi, C. pulchra, Carolus carinatus, C. stiriae, Corylonga aaroni, C. krottendorfi, C. leighi, C. lobata, C. loisae, C. mahmudae, C. triangula, Fletcherolus lanceolatus, F. monospinosus, Gelastocaledonia monteithi, Gelastocephalus velifer, Gurrundus fuscomarginatus, G. nectostylus, Guttala bernhardtae, G. mona, G. nickeli, G. robierae, Hartliebia towinna, Holgus ancistrus, H. liafredis, H. spiralis, H. unispinosus, Larivierea yalthi, L. yokunna, Lipsia mystrostylus, Melanoclypeus cristatus, M. uncinatus, Novotarberus flagellospinosus, N. pseudorphninus, N. remanei, Payastylus brichrius, P. gekiae, P. kernae, Rokebia australis, Ronaldia emeljanovi, Schuerrera clypeocarinata, S. ecarinata, Wernindia bubalis, W. lorda, W. rhomboidea, Yarnikada ulliae) are described. This increases the number of known Gelastocephalini from seven to 27 genera and from nine to 60 species. A new combination, Novotarberus jacobii, is proposed for Gelastocephalus jacobii from New Caldedonia and Cixius merula was transferred into the genus Schuerrera, resulting in a new combination, Schuerrera merula. A preliminary cladistic analysis of morphological data including all species of Gelastocephalini supported the monophyly of the tribe and its genera. The short male anal style is recognised as a synapomorphy for the tribe. The subtribe Rhigedanina was shown to be monophyletic whereas Gelastocephalina is paraphyletic. Three alternative hypotheses are presented to explain the current distribution of the tribe, which is restricted to Australia and New Caledonia. The species Novotarberus jacobii and Gelastocaledonia monteithi seem to be Gondwanan relicts.