Solving a thorny situation: DNA and morphology illuminate the evolution of the leaf beetle tribe Dorynotini (Coleoptera: Chrysomelidae: Cassidinae)

Abstract The Neotropical tribe Dorynotini is characterized by a conspicuous tubercle or spine adorning the elytra, which, along with a few other characters, has been used to differentiate its recognized five genera and two subgenera. However, relationships among these taxa and the evolutionary origin of the pronounced tubercle remain speculative. Here we present the first total-evidence phylogenetic reconstruction of Dorynotini to investigate the homology and evolution of the elytral tubercle. Our analyses are based on 89 discrete morphological characters and DNA sequence data from three gene regions. Phylogenetic relationships were inferred using Bayesian inference, maximum likelihood and maximum parsimony. Our analyses support the respective monophyly of Dorynotini and its genera and subgenera, except the paraphyletic Dorynota s.s. Species endemic to the Greater Antilles form a clade with three distinct morphotypes. Omoteina aculeata (Boheman, 1854) nov. comb. is transferred from the genus Dorynota, and Paratrikona Spaeth, 1923 nov. syn. is found to be congeneric with Omoteina Chevrolat, 1836. The spiniform projection is found to be plesiomorphic within Dorynotini and convergently reduced/lost in different lineages of the tribe. Some morphological characters defining dorynotine taxa are homoplastic, requiring re-evaluation guided by molecular analyses for more accurate classification and an improved understanding of taxon evolution.