A day-flashing Photinus firefly (Coleoptera: Lampyridae) from central Panamá: an emergent shift to predator-free space?

Abstract

Fireflies in the genus Photinus are well regarded for their luminescent nocturnal courtship displays. Here we report on a new firefly species, Photinus interdius, which is remarkable for its fully diurnal and luminescent courtship protocol. Males slowly flew near the ground searching for receptive females and emitted 800 ms, bright yellow light flashes at 3–4-s intervals. Male flights occurred as early as 13:10 and ceased before 18:00. We sequenced two mitochondrial loci and one genomic locus and combined these with those from 99 specimens representing 45 Photinus and 25 related firefly species. Bayesian inference resulted in a well-resolved phylogeny that placed this new species as the closest relative of, but basal to the Photinus clade. We propose that the adaptive significance of this extraordinary temporal shift in courtship niche is the outcome of a selective landscape that has optimized the trade-off between reduced predation risk and ease of mate-localization.