The Fall of Icarus: X-ray μCT assisted dissection of the rarely collected, montane genus <i>Nipponosphadasmus</i> (Curculionidae: Conoderitae) reveals highly atypical flightlessness in the supertribe

Abstract The weevil genus Nipponosphadasmus Morimoto, 1959 (Coleoptera: Curculionidae: Conoderitae), is a rarely collected, Shikoku Island (Japan) endemic lineage that has remained unstudied since its description. Here, we use X-ray μCT to dissect Nipponosphadasmus type material and also examine newly procured nontype material. Our dissections revealed complete reduction in the hindwings, an extremely rare example of flightlessness in the supertribe Conoderitae (approx. 2,200 species). Although species in Conoderitae are especially recognized as charismatic, strong, arboreal fliers with some species even mimicking flies, the flightless genus Nipponosphadasmus represents a novel shift away from the habits that characterize the group. Furthermore, collection data of the newly procured specimens and original type specimens suggest higher elevation, montane habitat preferences in Nipponosphadasmus. Flight loss is frequently observed in mountain-dwelling lineages across the insect orders, and the higher elevation habitat preferences of Nipponosphadasmus may have played a role in the evolution of hindwing reduction in this species as well. Traditional morphological examination of type material and the newly procured specimens also support N. yanoi Morimoto, 1959 syn. nov. as a new junior subjective synonym of N. coxalis Morimoto, 1959. To facilitate future molecular identification of Nipponosphadasmus, we publish the first DNA (CO1) barcodes for the genus.