PREDATORY MITES IN TROPICAL AUSTRALIA - LOCAL SPECIES RICHNESS AND COMPLEMENTARITY

Although little supporting data is available, mites (Acari) are often considered to be one of the 'hyperdiverse' taxa in tropical ecosystems . To test this assumption, we sampled single guilds of predatory mites (Hydracarina and Mesostigmata) in three different habitats (fresh wat er, rotting fungi, and forest foliage) across a range of sires in mons oonal, wet-tropical, and subtropical Australia. Most species (61%) wer e collected at a single site; as a result, all seven collector's curve s rose steeply with little indication of reaching asymptotes. Regional faunas ranged from 87-94 percent distinct and of the 247 species iden tified, 114 (46%) were previously unknown in Australia and appear to b e new. Even within taxonomically well-studied groups, such as the Hydr acarina and Phytoseiidae, we found many new species (32% and 60%, resp ectively). Our results suggest that the diversity of tropical mires is very high and comparable to that of many insect taxa. We propose a si mple model to explain our results, i.e. that in the tropics, high leve ls of complementarity between sires amplify local mire species richnes s. We rested this model by additional sampling, comparing within-site to between-site complementarity, and contrasting temperate with tropic al foliar Mesostigmata. As predicted by the model, collecting at new s ites continued to accumulate new species, complementarity was signific antly greater between-sites than within-sires (72 vs. 25%), and temper ate collections were more homogeneous and less diverse than tropical c ollections.