Molecular phylogeny of the tribe Luciini (Lepidoptera: Lycaenidae): systematics and life history evolution

The butterfly tribe Luciini (Theclinae), which currently includes 22 species, is restricted to Australia and mainland New Guinea and its adjacent islands. All species appear to have obligate, highly specialised associations with ants, and half of them are known or assumed to be myrmecophagous. Despite considerable progress in taxonomy and classification, no robust phylogenetic hypothesis currently exists for the tribe that could form a framework for a better understanding of the evolution of ant attendance in the group. Here, we reconstruct the phylogeny of the Luciini based on an extensive molecular dataset (up to 391 genetic loci for 101 ingroup samples representing 17 (77%) species and all four genera). Bayesian and maximum likelihood analyses found that the genus Pseudodipsas C. & R. Felder is polyphyletic, with the species Pseudodipsas cephenes Hewitson distantly related to the type species Pseudodipsas eone (C. & R. Felder). Comparative morphological evidence corroborates our molecular phylogenetic results and supports the establishment of a new monotypic genus, Paradipsas Braby, gen. nov., to accommodate the species Paradipsas cephenes (Hewitson) comb. nov. Phylogenetic relationships among genera in our well-supported trees are as follows: Lucia Swainson + (Pseudodipsas + (Paralucia Waterhouse & R.E. Turner + (Paradipsas + Acrodipsas Sands))). The ancestor of the tribe most likely associated with Dolichoderinae ants (possibly arboreal Anonychomyrma Donisthorpe) in wet biomes during the Eocene (stem-group: 37.91 ± 2.66 million years ago ‘Mya’). Differentiation of three of the butterfly genera in the Oligocene-Miocene (crown-group: 27.17 ± 3.75 Mya) involved shifts to other dolichoderine species (subterranean species of Anonychomyrma for Paralucia) or genera (Iridomyrmex Mayr for Lucia, Papyrius Shattuck for Acrodipsas) coinciding with shifts to drier biomes. Associations with other ant subfamilies represent more recent, secondary shifts within Luciini genera in the Miocene–Pliocene, and include single ant shifts to Formicinae (Notoncus Emery for Paralucia pyrodiscus (Rosenstock)) and Myrmicinae (Crematogaster Lund for Acrodipsas spp.). These patterns strongly suggest obligate ant attendance has been pivotal in the diversification of Luciini. Aspects of the ecology and biology of Paradipsas cephenes comb. nov. are clarified, particularly its critical habitat and attendant ant Anonychomyrma gilberti (Forel).