Evolution of the endemic Hawaiian cerambycid-beetles

Abstract

The Hawaiian cerambycid fauna presents one of the remarkable examples of great proliferation of species and form with adaptive radiation from a single ancestor. This fauna consists of over 135 species of plagithmysines (Clytini) plus one endemic species each of two somewhat widespread primitive genera (Megopis and Parandra) which breed primarily in rotten wood. There are also 17 species introduced by man. The plagithmysines evolved from a single immigrant ancestor species which probably came from Mexico or southern California a few million years ago. The group feeds in living trees and has remarkably specific host-tree food habits within a species of beetle, but has adapted to a large number of families (27) of trees for the whole group. Body form has diverged greatly, with the result that seven generic names have been proposed to accommodate the species. However, these have recently been reduced to the single genus Plagithmysus, with 5 subgenera, following the discovery of intermediate forms.