The evolution of Lampyridae, with special emphasis on the origin of photic behavior and signal system evolution (Coleoptera: Lampyridae)

The distribution, life history, and behavior of both larval and adult Lampyridae are summarized, as well as larval and adult morphological characters that define this family of beetles. The last larval and pupal stages of the North American firefly, Lucidota atra (G. A. Olivier 1790), are described and illustrated. The larva of L. atra was misidentified in the literature as a species in the genus Photinus. A discussion of the homology of abdominal sclerites in larval, pupal, and adult fireflies is provided. This work represents the first cladistic analysis of genera in the family Lampyridae and other closely related beetles. A monophyletic concept of Lampyridae is established. The phylogenetic positions of the luminous cantharoid families [Omalisidae, Rhagophthalmidae and Phengodidae] in relation to Lampyridae are discussed, as well as the implications of the evolution of bioluminescence and photic signaling in this group of beetles. The Rhagophthalmidae appears to include Dioptoma and Diplocladon (formerly located in Phengodidae) and the Phengodidae apparently includes Stenocladius (formerly of Lampyridae). Harmatelia, Drilaster and Pterotus are transferred to Elateroidea incertae sedis and not included in Lampyridae where they were sometimes placed. Through a phylogenetic analysis using adult morphological characters, it is shown that the origin of bioluminescence in cantharoid beetles appears to predate the origin of the family Lampyridae. The ability to produce and emit photic signals was first gained by larvae and appears to function as an aposematic warning display, while subsequently being gained in adults and used as sexual signals. This analysis also suggests that while pheromonal sexual signals are used basally in the family, these are used in conjunction with, and then subsequently replaced by, photic signals in some lampyrid lineages. Both photic signals and the photic organs used to produce them have become greatly elaborated in the fireflies that no longer employ pheromonal sexual signals. In addition, the ability to produce a flashed sexual signal appears to have arisen at least three times in the family Lampyridae. Convergent evolution also is evident in adult male photic organ morphology. Further, it is recommended that individual signal-system components be compared, rather than overall signal system complexity.