Phylogenetic relationships within Diplotaxini Kirby (Coleoptera: Melolonthidae: Melolonthinae) with emphasis on Liogenys Guérin-Méneville

Diplotaxini Kirby is one of the 29 tribes of Melolonthinae with Nearctic, Neotropical, Paleartic, Afrotropical and Oriental distribution. According to the current classification, Diplotaxini is composed of 706 species described in 21 genera. Neotropical Diplotaxini comprise 94 species, of which 78 are members of Liogenys Guérin Méneville, the largest Neotropical genus. Until now, no phylogenetic studies on Diplotaxini have tested whether the tribe is natural or artificial. This study tested the relationships among Diplotaxini genera, created hypotheses for better defining them, and assessed the monophyly of Liogenys. Cladistic analyses using 167 adult morphological characters were performed. The 83 included taxa represent three subfamilies of Melolonthidae, four tribes of Melolonthinae, and most genera of Diplotaxini, with emphasis on Liogenys. The data were analysed using parsimony under equal and implied weights. In both analyses, the traditional concept of Diplotaxini is shown to be a polyphyletic assemblage. Empecta Erichson and Clypeasta Fairmaire are closely related to Melolontha melolontha (Linnaeus) and Pseudoliogenys Moser close to Myloxenoides Martínez (Tanyproctini). Pachrodema Blanchard is identified as the sister group of Liogenys. The monophyly of both Pacuvia Curtis and Homalochilus Blanchard is confirmed and the paraphyly of Diplotaxis Kirby is suggested. The analyses strongly supported the polyphyly of Liogenys. To render this genus monophyletic, we transferred L. ferrugata Mannerheim (related to M. melolontha) to Phyllophaga Harris, and L. micropyga Burmeister to Diplotaxis, forming Diplotaxis micropyga (Burmeister, 1855) comb.n.; and included Homoliogenys tarsalis (Moser) and Hilarianus anguliceps Blanchard in Liogenys. As H. anguliceps is syn. junior of Liogenys punctaticollis, Hilarianus is synonymized with Liogenys. Hilarianus ovalis and Hilarianus rufinus are here assigned to Manonychus, and Hilarianus uniformis and Hilarianus suboblongus to Blepharotoma, forming: Blepharotoma uniformis comb.n., Blepharotoma suboblongus comb.n., Manonychus ovalis comb.n. and Manonychus rufinus comb.n.