How many cows are in the desert? Molecular phylogeny and species delimitation of the genus <i>Gyriosomus</i> ( <scp>Coleoptera: Tenebrionidae: Pimeliinae</scp> ) from the <scp>Atacama Desert</scp>

Abstract Gyriosomus is a genus of charismatic tenebrionids endemic to Chile, commonly known as vaquitas del desierto ’. They are distributed from ~25° S to ~34° S, almost exclusively within the Coquimban Biogeographic Province. They are notable for the explosive and massive appearance of adults associated with blooming desert events in Atacama. Since their initial description in 1834, 44 species have been classified, but the genus has not undergone a comprehensive systematic revision. Using molecular markers, taxonomic issues related to the use of morphological characters have recently been identified. In this study, we evaluated the phylogenetic relationships within Gyriosomus and the congruence of the current taxonomic scenario with our results. We conducted an exhaustive sampling across the entire distribution range of the genus. Specifically, we reconstructed a molecular phylogeny based on four genes (cytochrome c oxidase subunit I ‘COI’, wingless ‘Wg’, carbamoyl phosphate synthetase ‘CAD’ and 28S ribosomal RNA ‘28S’) with 41 of the 44 described species and performed unilocus and multilocus molecular species delimitation analyses. The phylogenetic analyses indicate that the 45 genetically evaluated species are organized into nine distinct clades. Only half of the previously described species were validated by the molecular species delimitation analyses. The rest are likely new candidate species, with some potentially being synonyms. External morphology alone may not be sufficient to support the taxonomy due to the plasticity of these characters. We also found a zone of ‘High Cladistic Sympatry’, inhabited by representatives of different clades. In this zone, we encountered polymorphic and cryptic species and a high degree of convergence between clades, which complicates the study of these darkling beetles.