Four New Species of Haplocauda, with Notes on the Evolutionary Convergence of Copulation Clamps in Lucidotini (Coleoptera: Lampyridae: Lampyrinae)

Lampyrinae Lucidotini contains nearly a third of the world's Lampyridae. The lack of revisions and the overlap of diagnostic features across taxonomic levels have hindered identification and, therefore, further studies of Lucidotini taxa. The use of terminalia and genital traits in Lucidotini phylogenies has been fundamental to inform and update the genus-level delimitations in this group. One important open question is whether the presence of increased-length abdominal segment VIII (in relation to segment VII) in the closely related genera <i>Scissicauda</i> and <i>Haplocauda</i> is synapomorphic or homoplastic. In recent collecting efforts combined with studies of specimens deposited in different scientific collections, we found specimens hypothesized as four new firefly species from the Amazon basin that share the unique characteristics of the male abdomen of <i>Haplocauda</i> species. To test the hypothesis that these new species are monophyletic and sisters to <i>Haplocauda</i> species, and that the augmented segment VIII is synapomorphic to <i>Scissicauda</i> + <i>Haplocauda</i>, we ran phylogenetic analyses building upon a pre-existing character matrix, including a wide sample of Lucidotini and neighboring branches. Our results support the placement of the four new species described here (<i>H. lata</i> sp. nov., <i>H. amazonensis</i> sp. nov., <i>H. aculeata</i> sp. nov. and <i>H. antimary</i> sp. nov.) in <i>Haplocauda</i>. Importantly, one species with regular-sized segment VIII sclerites was recovered as the earliest diverging lineages of <i>Haplocauda</i>, suggesting that segment VIII was augmented at least twice in the Lucidotini-the other one being within <i>Scissicauda</i>. We also report, for the first time, a sympatry between <i>Haplocauda</i> species. We revised the definition of <i>Haplocauda</i> and updated the distribution of <i>H</i>. <i>mendesi</i> and the existing key to species.