bioRxiv2022
The Euteliidae stand apart in the Noctuoidea as the second smallest family, but most highly specialized in terms of larval hostplant relationships, favouring plant families with high levels of resin or latex, including the family dominant in Oriental lowland forests, the Dipterocarpaceae. Given the proportionally large foliage biomass represented by dipterocarps, exploitation of this abundant resource by lepidopteran defoliators is surprisingly low, and the Euteliidae may have achieved this through pre-adaption to dipterocarp chemical defences. Therefore, to assess this, we performed a molecular phylogenetic analysis on the family Euteliidae to clarify deep divergences and elucidate evolutionary relationships at the level of the subfamily, tribe, and genus. Our dataset consists of 6.3 kbp of one mitochondrial and seven nuclear DNA loci and was analyzed using model-based phylogenetic methods, i.e., maximum likelihood and Bayesian inference. We attempted to diagnose apomorphic morphological character states for Euteliidae and each monophyletic group within the family. Additionally, the evolution of hostplant use was reconstructed and a molecular-dating approach was conducted to assess the ages of major lineages within Euteliidae. We present an updated phylogenetic hypothesis for Euteliidae consisting of two strongly supported subfamilies: Euteliinae and Stictopterinae. Within Stictopterinae there are two tribes: Stictopterini and Odontodini. Several genera (e.g., Targalla, Paectes, Marathyssa, Eutelia) were found to be polyphyletic and require taxonomic revision. Two new genera (Niklastelia and Pellinentelia) are described and several taxonomic changes (e.g., new combinations and new synonymies) are made. The Neotropical genus Thyriodes, currently included in Euteliidae, is found to be associated with Erebinae (Erebidae). The divergence time estimate for the split between the Euteliidae and Noctuidae is at 53 my, and the Euteliidae split into the subfamilies Euteliinae and Stictopterinae at 42 my. In Stictopterinae, the tribes Stictopterini and Odontodini split at 31 my and the Euteliinae began a much more complex diversification at 34 my. Ancestral hostplant reconstruction identified Malpighiales (e.g., Clusiaceae) as the ancestral larval hostplant order for the family Euteliidae. The ancestors of Stictopterinae also appear to have been Malpighiales feeders, but then split into exclusive specialisms on Malvales (Odontodini) and Malpighiales (Stictopterini) hostplants. Larvae of Stictopterini appear to be restricted to Clusiaceae, apart from a few records from Dipterocarpaceae. In Euteliinae, Anacardiaceae are predominant as larval hosts. Thus, all hosts in the family are lactiferous, possibly providing some degree of pre-adaptation for exploiting Dipterocarpaceae.