Detailed description of the new genus and speceis, Cretophengodes azari Li, Kundrata, Tihelka and Cai sp. nov.

<p><span>Bioluminescent beetles of the superfamily Elateroidea (fireflies, fire beetles, glow-worms) are the most speciose group of terrestrial light-producing animals. The evolution of bioluminescence in elateroids is associated with unusual morphological modifications, such as soft-bodiedness and neoteny, but the fragmentary nature of the fossil record discloses little about the origin of these adaptations. We report the discovery of a new bioluminescent elateroid beetle family from the mid-Cretaceous of northern Myanmar (<i>ca</i>. 99 Ma), Cretophengodidae fam. nov. <i>Cretophengodes azari</i> gen. et sp. nov. belongs to the bioluminescent lampyroid clade, and represents a transitional fossil linking the soft-bodied Phengodidae + Rhagophthalmidae clade and hard-bodied elateroids. The fossil male possesses a light organ on the abdomen which presumably served a defensive function, documenting a Cretaceous radiation of bioluminescent beetles coinciding with the diversification of major insectivore groups such as frogs and stem-group birds. The discovery adds a key branch to the elateroid tree of life and sheds light on the timing of the evolution of soft-bodiedness and historical biogeography of elateroid beetles.</span></p>