Systematics of giant neotropical fireflies and their kin (Lampyridae: Lampyrinae)

The Lampyrinae tribe Cratomorphini includes some of the largest and most widespread New World fireflies. Their overlapping genus-level diagnoses are based on a few traits related to sexual signaling known to be fast-evolving and labile within-genus in other Lampyrinae taxa. To clarify the taxonomy and investigate the morphological evolution in Cratomorphini, Lamprocerini, and closely related taxa, we inferred the phylogenetic relationships of 50 species using 97 adult morphological characters contrasting the results of Maximum Parsimony Analysis and Bayesian Inference. Using a statistical framework, we demonstrate that terminalia and genitalic traits are less homoplastic than signaling or other somatic traits. Cratomorphini was recovered as polyphyletic, with four distinct clades, as follows: (i) Cratomorphus (partim: the type species, C. splendidus, and associated species) + Erythrolychnia bipartita; (ii) Cratomorphus (partim; transferred here to Nyctocera gen. nov. [Lamprocerini]); (iii) Cratomorphus (partim; transferred here to Bituca gen. nov. [Lampyrinae incertae sedis]) and (iv) (Micronaspis ((Aspisomoides, Pyractomena) Aspisoma)). Based on these results, we redefine Cratomorphini and Lamprocerini and present updated diagnoses for both tribes. We propose a new tribe, Aspisomini trib. nov. and establish two new genera: Nyctocera gen. nov. (within Lamprocerini sensu nov.) and Bituca gen. nov. (incertae sedis). Four species formerly assigned to Cratomorphus sensu nov. are transferred - three to Nyctocera gen. nov., and one to Bituca gen. nov. - and all are redescribed based on type and additional material. We illustrate all diagnostic features, and provide updated keys to the genera of Cratomorphini sensu nov., Aspisomini trib. nov., and Lamprocerini sensu nov. Additionally, we identify and discuss synapomorphies for clades previously recovered only in DNA-based phylogenies. Our work stresses the need for thorough investigations of morphological data, especially of the terminalia and genitalia, to elucidate the phylogeny of fireflies.