The effectiveness of DNA-based delimitation in Synchonnus net-winged beetles (Coleoptera: Lycidae) assessed, and description of 11 new species

Synchonnus Waterhouse, 1879 from Australia is revised. Achras Waterhouse, 1879 and Enylus Waterhouse, 1879 are found to be junior synonyms of Synchonnus due to the absence of diagnostic characters and result in the new combinations of Synchonnus amplus (Kleine, 1930), S. limbatum (Waterhouse, 1877), and S. segregatus (Waterhouse, 1879). Synchonnus is reported from the Australian mesic and monsoon zones, and 11 new species are described: S. flavonotatum sp. nov., S. maseki sp. nov., S. ailaketoae sp. nov., S. dubenovae sp. nov., S. chilvertonensis sp. nov., S. slipinskii sp. nov., S. monteithi sp. nov., S. eungellensis sp. nov., S. crypticum sp. nov., S. variabilis sp. nov. and S. campestris sp. nov. The morphology-based species limits are compared with delimitation inferred from the shape of the phylogenetic tree and genetic distance. DNA-based species limits agree with morphological delimitation in two clades, but a deep conflict was identified in another clade of Synchonnus consisting of three species with allopatric distributions and diversified genitalia, but strong similarities in cox1 mtDNA sequences. The failure of molecular species delimitation in some Synchonnus points to our inability to predict the performance of a barcoding approach even in closely related lineages and calls for an integrative taxonomical approach whenever possible. The Synchonnus fauna of Australia is presented as highly diverse and fragmentation of habitat in the last similar to 15 million years is hypothesised as the principal factor leading to the observed alpha-taxonomic diversity.