Phylogeny of Scissicauda Species, with Eight New Species, including the First Photinini Fireflies with Biflabellate Antennae (Coleoptera: Lampyridae)

Abstract

Photinini is the largest tribe of Lampyrinae fireflies, with over 30 genera and nearly 750 species, and includes taxa where adults may or may not have light organs. A focus on taxa with bioluminescent adults left the taxonomy of dark fireflies in poor condition compared to taxa with lit adults. A recent phylogenetic study based on molecular data supported the transfer of Scissicauda McDermott, 1964—traditionally placed in Amydetinae due to the flabellate antenna of its type species—to Photinini at a branch sided with Pyropyga Motschulsky, 1852 and Pyractonema Solier, 1849. Such placement had never been recovered before in morphology-based studies, and the consequences for the interpretation of character evolution in this lineage are yet to be addressed. Moreover, Scissicauda was previously thought to be endemic to the Atlantic Forest. Here, through phylogenetic analyses of 38 taxa and 108 morphological characters, we (i) expand on the concept of Scissicauda to include S. antennata sp. nov., S. asymmetrica sp. nov., S. aurata sp. nov., S. biflabellata sp. nov., S. gomesi sp. nov., S. jamari sp. nov., S. neyi sp. nov., S. truncata sp. nov., and (ii) transfer Lucidota malleri Pic, 1935 and, therefore, S. malleri comb. nov. We also recover Pyropyga + Pyractonema as sister to Scissicauda + Haplocauda, providing the first morphological evidence for their sisterhood. Noteworthy, the new species S. biflabellata sp. nov. and S. asymmetrica sp. nov. stand out as the first known Photinini species with biflabellate antennae. In addition, our study reports the first Scissicauda species in the Amazon (S. antennata sp. nov., S. aurata sp. nov., S. gomesi sp. nov., S. jamari sp. nov., and S. truncata sp. nov.) and Cerrado biome (S. neyi sp. nov.). Our study highlights the value of continued sampling and phylogenetic analyses of South American fireflies towards a revised classification and deeper understanding of this lineage.