Phylogenomic relationships of bioluminescent elateroids define the 'lampyroid' clade with clicking Sinopyrophoridae as its earliest member

Bioluminescence has been hypothesized as aposematic signalling, intersexual communication and a predatory strategy, but origins and relationships among bioluminescent beetles have been contentious. We reconstruct the phylogeny of the bioluminescent elateroid beetles (i.e. Elateridae, Lampyridae, Phengodidae and Rhagophthalmidae), analysing genomic data ofSinopyrophorusBi & Li, and in light of our phylogenetic results, we erect Sinopyrophoridae Bi & Li,stat.n. as a clicking elaterid-like sister group of the soft-bodied bioluminescent elateroid beetles, that is, Lampyridae, Phengodidae and Rhagophthalmidae. We suggest a single origin of bioluminescence for these four families, designated as the 'lampyroid clade', and examine the origins of bioluminescence in the terminal lineages of click beetles (Elateridae). The soft-bodied bioluminescent lineages originated from the fully sclerotized elateroids as a derived clade with clickingSinopyrophorusand Elateridae as their serial sister groups. This relationship indicates that the bioluminescent soft-bodied elateroids are modified click beetles. We assume that bioluminescence was not present in the most recent common ancestor of Elateridae and the lampyroid clade and it evolved among this group with some delay, at the latest in the mid-Cretaceous period, presumably in eastern Laurasia. The delimitation and internal structure of the elaterid-lampyroid clade provides a phylogenetic framework for further studies on the genomic variation underlying the evolution of bioluminescence.

Automated summary

The study suggests that bioluminescence in Elateridae, Lampyridae, Phengodidae, and Rhagophthalmidae has a single origin, forming the 'lampyroid clade'. Soft-bodied bioluminescent elateroid beetles likely evolved from fully sclerotized elateroids, with bioluminescence possibly arising in Elateridae in the mid-Cretaceous period in eastern Laurasia. This research provides a phylogenetic framework for studying genomic variation in the evolution of bioluminescence.