Phylogeny of the flea beetles (Galerucinae: Alticini) and the position of Aulacothorax elucidated through anchored phylogenomics (Coleoptera: Chrysomelidae: Alticini)

The Alticini comprise 601 genera and 10,000 species, including plant pests. Their phylogeny remains largely unresolved, inhibiting taxonomic stability, specimen identification and biological understanding. Here, we generated a genomic dataset using Anchored Hybrid Enrichment (AHE) for 54 genera of Alticini, 16 of Galerucini, and 40 of other Chrysomelidae to test the monophyly of Alticini, and its genus groups, and to examine the utility of established diagnostic characters. Maximum likelihood and coalescent phylogenetic analyses produced resolved and overall congruent topologies. Synetinae was sister to Cassidinae + Eumolpinae + Lamprosomatinae + Cryptocephalinae, supporting its recognition as valid. Within Galerucinae, Aulacothorax Boheman was found as sister to Galerucini + Alticini (each monophyletic). Tribe Serraticollini White stat. rev. is reinstated as valid, as the oldest available name for the higher lineage containing Aulacothorax. We extend Crowson's classification, with Alticini, Galerucini, and Serraticollini united under Galerucinae. We transfer genera Chalaenosoma Jacoby, Demarchus Jacoby, and Mandarella Duvivier from Alticini to Galerucini incertae sedis, and confirm prior transfers of Hespera Weise, Luperomorpha Weise and Nonarthra Baly from Alticini to Galerucini incertae sedis. Galerucini and Alticini are reciprocally monophyletic following these transfers. Our work recovered multiple evolutionary origins of jumping hind legs in Galerucinae, hindering straightforward morphological diagnosis of tribes. We provide diagnoses for Alticini, Galerucini and Galerucinae, but these require dissection of female genitalia. We achieved some phylogenetic resolution within Alticini, but found few adult morphological characters to define subclades. Our results indicate that with future denser taxon sampling, AHE phylogenomics could provide a robust basis for subtribal classifications.