Phylogeography and species distribution modeling unveil unnoticed Pliocene diversity: the case of a montane Iberian bush-cricket, Antaxius spinibrachius (Orthoptera: Tettigoniidae)

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Abstract The geographic distribution and systematics of many groups of insects are still understudied across large geographic areas of the Iberian Peninsula. This lack of knowledge and the fact that many species have a complex evolutionary history due to the existence of “refugia within refugia” have hindered the taxonomic description of the true biodiversity in the Iberian Peninsula. Here, we discuss the evolutionary history of a flightless Iberian bush-cricket Antaxius spinibrachius (Fischer, 1853) using 1 nuclear and 2 mitochondrial markers. We applied species distribution modeling to design sampling strategies in climatically favorable areas and to detect missing isolated populations or unknown lineages. Following the species distribution modeled using all of the presence records available, we discovered 4 new isolated populations in Sierra Madrona, Serra de São Mamede, Sierra de Montánchez, and Sierra de la Demanda. Phylogenetic analyses recovered 2 major Pliocene lineages with a north–south geographic speciation pattern in the Iberian Peninsula. This north–south vicariant event split the common ancestor of these species on either side of the Tagus Valley, probably associated with the Pliocene climate change and the reorganization of paleobasins of the western Iberian Peninsula during the Miocene–Pliocene. We described the southern Iberian Plateau lineage of Antaxius as a new species of bush-cricket based on phylogenetic and morphological evidence, Antaxius oretanus sp. nov. We assessed the conservation status of the new species as “VU B2ab(iii,v)” under the IUCN criteria.