The flightless weevil genus Trigonopterus Fauvel (Coleoptera, Curculionidae, Cryptorhynchinae) is extremely diverse in New Guinea, New Caledonia and the Pacific Islands. Presently, there exist 90 described species worldwide, but this number will multiply when the group is revised. Based on the material available from New Guinea, there exist an estimated 500-1000 species on this island alone. Thus, it belongs to the list of hyperdiverse genera, such as the tiger-beetles of Cicindela, or the ants of the genus Pheidole.
The present project is dealing with various aspects of this genus. It should include work on its taxonomy, morphology and ecology. The purpose is to document the hyperdiversity of Trigonopterus and to explain its causes. Morphological adaptions to thanatosis behaviour might play a role; defensive stridulation may be another factor triggering hyperdiversity. When reliable data on the phylogeny are obtained it will be possible to identify key-characters as apomorphies of hyperdiverse clades.
Trigonopterus seems to be in the centre of a mimicry complex. Different groups of Curculionidae, Chrysomelidae and a group of jumping spiders imitate the appearance of these weevils. This pressure to convergence causes problems when using morphological characters for phylogenetic analysis. Thus, a molecular approach will be taken to detect such cases of convergent evolution.
East of Wallace-line various species are dominant both on foliage and in the litter layer of tropical forests. Towards the west, diversity not only decreases, but foliage-frequenting species disappear. In Java, Trigonopterus are restricted to the litter layer. Usually, the species are highly endemic and populations are scattered over the Sunda arc reaching the westernmost record in East Sumatra. Presumably, the Javanese fauna of Trigonopterus consists of two monophyletic groups that invaded independently from the East.
There is some overlap with the project on the leaf litter inhabiting arthropods of Java.
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