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We understand very little about the timing and origins of bioluminescence, particularly as a predator avoidance strategy. Understanding the timing of its origins, however, can help elucidate the evolution of this ecologically important signal. Using fireflies, a prevalent bioluminescent group where bioluminescence primarily functions as aposematic and sexual signals, we explore the origins of this signal in the context of their potential predators. Divergence time estimations were performed using genomic-scale datasets providing a robust estimate for the origin of firefly bioluminescence as both a terrestrial and as an aerial signal. Our results recover the origin of terrestrial beetle bioluminescence at 141.17 (122.63–161.17) Ma and firefly aerial bioluminescence at 133.18 (117.86–152.47) Ma using a large dataset focused on Lampyridae; and terrestrial bioluminescence at 148.03 (130.12–166.80) Ma, with the age of aerial bioluminescence at 104.97 (99.00–120.90) Ma using a complementary Elateroidea dataset. These ages pre-date the origins of all known extant aerial predators (i.e. bats and birds) and support much older terrestrial predators (assassin bugs, frogs, ground beetles, lizards, snakes, hunting spiders and harvestmen) as the drivers of terrestrial bioluminescence in beetles. These ages also support the hypothesis that sexual signalling was probably the original function of this signal in aerial fireflies. 

Firefly (Coleoptera: Lampyridae) taxonomy has undergone numerous changes over the past 100 years. In order to help provide stability to the group, types for several of the Lampyridae of the Biologia Centrali Americana were determined or designated in early 2019. Here we provide treatments for the remaining Lampyridae and determine the holotype specimens for four species and designate lectotype specimens for 33 species. 

The Biologia Centrali Americana (B.C.A.) is comprised of eight volumes that deal specifically with Coleoptera. These volumes were split into 18 parts and were published between 1879 and 1911. The family Lampyridae was treated in two parts, the main text (1881) with a supplement (1884). Within volume three, part 2, Gorham lists ~90 species in 14 genera, not including the Phengodini subfamily. Of these, Gorham provided original descriptions for 37 species. During recent research visits (2018 and 2020) the authors were able to study material pertinent to the B.C.A. We were able to confidently designate holotypes, lectotypes, and paralectotypes following ICZN articles 73.1 and 74.1 within these species. Two species described by Gorham (1881) are not treated here. Phaenolis nirgricollis was located with a single specimen, already designate as the holotype. Two female syntypes of Photinus consanguineous were located, however Oliver (1907) synonymized these females with Photinus pyralis. These designations contribute to a larger taxonomic effort to stabilize the nomenclature of this group. The species described in the supplement will be treated in a future work. Subfamilies are listed according to Martin et al. (2019) and genera/species within each subfamily are listed according to the order in Gorham (1881). 

Additional work on the islands of Vanuatu has improved our understanding of the actual diversity of South Pacific coastal fireflies. Prior to recent fieldwork in Vanuatu, the only known lampyrid from Vanuatu was Atyphella aphrogeneia (Ballantyne), a coastal species also found in Papua New Guinea. After further examination, we determined that specimens from Vanuatu formerly classified as Atyphella aphrogeneia actually belong to an undescribed species. New species, Atyphella maritimus Saxton and Powell and Atyphella marigenous Saxton and Bybee, are described from specimens collected in Vanuatu. An updated key for coastal Atyphella in the South Pacific is provided. 

Abstract Fireflies (Lampyridae Rafinesque) are a diverse family of beetles which exhibit an array of morphologies including varying antennal and photic organ features. Due in part to their morphological diversity, the classification within the Lampyridae has long been in flux. Here we use an anchored hybrid enrichment approach to reconstruct the most extensive molecular phylogeny of Lampyridae to date (436 loci and 98 taxa) and use this phylogeny to evaluate the higher-level classification of the group. None of the currently recognized subfamilies were recovered as monophyletic with high support. We propose several classification changes supported by both phylogenetic and morphological evidence: 1) Pollaclasis Newman, Vestini McDermott (incl. Vesta Laporte, Dodacles Olivier, Dryptelytra Laporte, and Ledocas Olivier), Photoctus McDermott, and Araucariocladus Silveira & Mermudes are transferred to Lampyridae incertae sedis, 2) Psilocladinae Mcdermott, 1964status novum is reestablished for the genus Psilocladus Blanchard, 3) Lamprohizini Kazantsev, 2010 is elevated to Lamprohizinae Kazantsev, 2010status novum and Phausis LeConte is transferred to Lamprohizinae, 4) Memoan Silveira and Mermudes is transferred to Amydetinae Olivier, and 5) Scissicauda McDermott is transferred to Lampyrinae Rafinesque. 

Glowing fireflies dancing in the dark are one of the most enchanting sights of a warm summer night. Their light signals are ‘love messages’ that help the insects find a mate – yet, they also warn a potential predator that these beetles have powerful chemical defenses. The light comes from a specialized organ of the firefly where a small molecule, luciferin, is broken down by the enzyme luciferase. Fireflies are an ancient group, with the common ancestor of the two main lineages originating over 100 million years ago. But fireflies are not the only insects that produce light: certain click beetles are also bioluminescent. Fireflies and click beetles are closely related, and they both use identical luciferin and similar luciferases to create light. This would suggest that bioluminescence was already present in the common ancestor of the two families. However, the specialized organs in which the chemical reactions take place are entirely different, which would indicate that the ability to produce light arose independently in each group. Here, Fallon, Lower et al. try to resolve this discrepancy and to find out how many times bioluminescence evolved in beetles. This required using cutting-edge DNA sequencing to carefully piece together the genomes of two species of fireflies (Photinus pyralis and Aquatica lateralis) and one species of click beetle (Ignelater luminosus). The genetic analysis revealed that, in all species, the genes for luciferases were very similar to the genetic sequences around them, which code for proteins that break down fat. This indicates that the ancestral luciferase arose from one of these metabolic genes getting duplicated, and then one of the copies evolving a new role. However, the genes for luciferase were very different between the fireflies and the click beetles. Further analyses suggested that bioluminescence evolved at least twice: once in an ancestor of fireflies, and once in the ancestor of the bioluminescent click beetles. More results came from the reconstituted genomes. For example, Fallon, Lower et al. identified the genes ‘turned on’ in the bioluminescent organ of the fireflies. This made it possible to list genes that may be involved in creating luciferin, and enable flies to grow brightly for long periods. In addition, the genetic information yielded sequences from bacteria that likely live inside firefly cells, and which may participate in the light-making process or the production of potent chemical defenses. Better genetic knowledge of beetle bioluminescence could bring new advances for both insects and humans. It may help researchers find and design better light-emitting molecules useful to track and quantify proteins of interest in a cell. Ultimately, it would allow a detailed understanding of firefly populations around the world, which could contribute to firefly ecotourism and help to protect these glowing insects from increasing environmental threats.