Eur. J. Entomol. 101: 251–259, 2004 ISSN 1210-5759 Host specificity or habitat structure? – The epicortical beetle assemblages in an Australian subtropical rainforest FLORIAN MENZEL1, 2, ROGER L. KITCHING1 and SARAH L. BOULTER1 1Australian School of Environmental Studies, Griffith University, Nathan, Queensland 4207, Australia; e-mail:
[email protected] 2Department of Animal Ecology and Tropical Biology, Biozentrum Am Hubland, Julius-Maximilian’s University, 97074 Würzburg, Germany Key words. Coleoptera, alpha diversity, bark, rainforest, Australia Abstract. We have investigated the relative importance of bark roughness and host tree species in determining the diversity and make-up of coleopteran assemblages on the trunks of trees in sub-tropical rainforest in south-east Queensland, Australia. There are clear, statistically significant, patterns in the composition of the assemblages which reflect bark roughness. Rougher bark had associ- ated greater species and family richness, a higher proportion of “rare” species, a higher value for Shannon diversity and lower values for the Simpson and Berger-Parker Index (measures of dominance within the sample). The data support strongly the idea that there is a bark-specific beetle assemblage. The rougher bark was associated with significantly greater numbers of an anobiid species, Dorca- toma sp., and of the latridiid species Aridius australicus. Rougher bark also harboured significantly larger species. The most likely explanation for this seems to be related to the physical heterogeneity and biological complexity of the habitat, presenting, as it does, greater opportunities for shelter, feeding specialisation and intra-species aggregation. Rougher bark contained a higher proportion of both predatory and xylophagous groups than did smoother categories.