Why are there so many Laparocerus weevils? The swarm of 261 beetle species and subspecies in Madeira, Salvages and the Canary Islands is the result of a blend of adaptive and non-adaptive evolution in old volcanic archipelagos. These have plenty of environmentally dissected islands subject to a dynamics of construction and deconstruction. A twenty year-long prospection and a DNA phylogenetic analysis reveal their monophyly, internal relationships, and plausible pathways of colonisation, which started in the late Miocene.
Within a timeframe of about 9 million years, sequential radiation events have generated several monophyletic groups, 25 in total, that have been recognised as subgenera of Laparocerus. Colonisation routes, habitat shifts, disruption of populations by volcanism, dispersal by massive landslides, and other important factors for speciation are discussed in depth.
Laparocerus weevils are all flightless and most taxa are exclusive to one single island – seventeen in total – having occupied almost all habitats, from the coastal shrublands to the sclerophyllous woodlands, evergreen cloud-forest, pine woodlands, high-mountain shrublands and the underground environment (volcanic lava-tubes). They thus show extraordinary morphological and ecological plasticity. Only two species inhabit NW Africa, the nearest continental land, but as a result of a back-colonisation. The richest island is Tenerife (2034 km2) with 68 species and subspecies. Overall, there is an outstanding ratio of one endemic Laparocerus per 31 km2, a record not beaten by any other plant or animal genus in Macaronesia.
If oceanic islands have been traditionally considered as laboratories of evolution and species-producing machines, Laparocerus will become an ideal model species for broadening research into dispersal and speciation processes of all kinds. Such a group provides a fine-grain picture of nature and evolution at work.
To assist in this endeavour, this book provides a full revision of the genus Laparocerus, with descriptions of all 264 species and subspecies – doubling the number previously known – keys for their identification, 374 macro-photographs of the imagos, 50 plates with line drawings of their genitalia and other internal pieces, and 47 distribution maps. It also incorporates a detailed anatomical study (13 plates) of one species including preimaginal stages, and chapters dealing with their breeding biology, ecology (food plants, habitats, etc.), and behaviour. Their natural history, in other words.