Tropical mountains are hotspots of biodiversity, hosting many endemic species. Here, we propose Luciuranus gen. nov. and four new firefly species dwelling in montane habitats of the Brazilian Atlantic Rainforest. Luciuranus gen. nov. is unique in the shape of the last abdominal segments of both males and females, varying in a clear species-specific fashion. Luciuranus josephi sp. nov. and L. jameshooki sp. nov. are restricted to Serra dos Órgãos mountain range, while L. dextrus sp. nov. and L. sinistrus sp. nov. are restricted to Serra da Mantiqueira formation. DNA barcoding with COI gene confirmed species identities and male–female associations. We propose that terminalia structures work together as a lock-and-key mechanism, avoiding hybridization in overlapping zones along heterogeneous habitats, such as montane forests, where temperature, moisture, and vegetation cover can change significantly even in small spatial and temporal scales. Such morphological displacement is discussed in terms of sexual selection on both male and female features. We also provide detailed morphological descriptions, illustrations, and a key to species based on males and females. http://zoobank.org/urn:lsid:zoobank.org:pub:05598351-4655-49E5-9011-B90DFC7D9435

Fireflies (Coleoptera: Lampyridae) are charismatic insects that have been fruitful model systems in biotechnology. However, lack of information about firefly taxonomy and ecology renders species identification a hard task, especially in the Neotropical region, where fireflies are most diverse. A major gap in the literature on Neotropical fireflies is the lack of knowledge on species’ ecological niches and habitats, which are fundamental aspects for understanding their biology. Here, we provide an annotated checklist of the firefly fauna of the Serra dos Órgãos mountain range (Rio de Janeiro State, Southeastern Brazil), with information on the natural history of each species. We assembled data in three ways: monthly sampling with Malaise traps and active search along an elevational transect from 130 to 2,170 m, over 2 years (2014–2016), extensive field observations, and extracted from historical species records for the Serra dos Órgãos from museum specimens in key collections in Brazil and Europe. We provide a taxonomic key to the genera recorded in the region, and a differential diagnosis for each species, highlighting key references for each taxon. We report 58 species representing 21 genera, making the Serra dos Órgãos one of the richest firefly hotspots on Earth. Most species are restricted to one or two habitat types and/or just one of the regional seasons (warm or cool), and many were only collected either by malaise traps or active search, underlining the importance of sampling different habitat types and seasons, and using different sampling methods when surveying fireflies. Out of the 51 species observed in the field, 49 were active either during the day or the night, although two species – Photuris elliptica and Pyrogaster nigrolineatus – were active in both periods, which is rare in fireflies.

Here, we propose Uanauna gen. nov. (Lampyridae: Photinini), a new monotypic genus of fireflies endemic to the Brazilian Atlantic Forest. Uanauna angaporan sp. nov. occurs in Submontane and Montane forest habitats at the Serra do Mar mountain range, in the Southern Fluminense region (Rio de Janeiro State, Southeastern Brazil). The new species was recorded both on the mainland, at the municipality of Itaguaí and Rio de Janeiro, and at the continental island of Ilha Grande, in Angra dos Reis, at the Rio de Janeiro State. An occurrence map and illustrations of diagnostic features are given for the new taxa, as well as a key to Lucidotina genera in Brazil.

Here, we describe Araucariocladus amfractus sp. nov., and compare it to the previously monotypic type-species, A. hiems. The new species can be distinguished from A. hiems by the following combination: colour pattern overall dark-brown; pedicel three times shorter than antennomere III and slightly wider than long; distance between antennal sockets as wide as 3/5 clypeal width; labial palpomere III with sides divergent towards apex, apical margin longer than dorsal and shorter than ventral margin; pronotum 1.5x wider than long, anterior margin somewhat sinuose, with a shallow angle anteriad, posterior margin almost straight. A. amfractus sp. nov. is, prima facie, endemic to the Itatiaia Massif, part of the Mantiqueira Mountain Range, Southeastern Brazil. We provide illustrations of the diagnostic features, and an occurrence map for the Araucariocladus species. Finally, we report a previously unrecognized intra-specific variation in the antennomere numbers of A. hiems, a feature also present in Araucariocladus amfractus sp. nov., and adjust the generic diagnosis to include species with 17 or 18 antennomeres. [Zoobank LSID: urn:lsid:zoobank.org:act:C335B064-FBD4-4256-983D-B17DF06BAA0D]