Phylogeny and evolution of an endemic radiation of longhorn beetles (Cerambycidae: Dorcasomini) in Madagascar

Madagascar, the world’s oldest island, is a global hotspot of biodiversity and endemism shaped by tens of millions of years of isolation. Its diverse ecosystems—from arid spiny thickets to humid rainforests—have fostered both ancient relict lineages and spectacular in situ radiations. Among its remarkable fauna, longhorn beetles of the tribe Dorcasomini (Cerambycidae: Cerambycinae) are especially notable. Although they represent just 1% of global cerambycid diversity, Dorcasomini comprise roughly 25% of Madagascar’s longhorn beetle fauna, exhibiting exceptional morphological and ecological diversity suggestive of an adaptive radiation. Despite their prominence in the Malagasy beetle fauna, the evolutionary history of Dorcasomini remains poorly understood. This study presents a phylogenetic framework for the group, integrating molecular data, species distributions, and morphological traits to explore their diversification. We investigate the timing and geographic origins of Malagasy Dorcasomini, test for ecological and taxonomic patterns of diversification, and assess their contribution to the island’s endemic insect biodiversity. These findings shed light on how dispersal, isolation, and ecological opportunity have shaped one of Madagascar’s most striking beetle radiations.