The Taxonomic Composition of the Arthropod Fauna Associated with an Australian Rainforest Tree

The composition of the arthropod fauna foraging within the canopy of Argyrodendron actinophyllum Edlin (Sterculiaceae) in a subtropical rainforest near Brisbane, Australia, was investigated during a 2-year field study. Collecting methods included flight interception traps, restricted canopy fogging, and hand-collecting. Over 50 000 canopy arthropods were collected and about 760 species sorted, from which 660 were identified at least to the generic level by taxonomists. The arthropod fauna of A. actinophyNum is characterised by the abundance of Clubionidae, Theridiidae, Psylloidea, Phlaeothripidae, Chrysomelidae, Corylophidae, Curculionidae and Braconidae, and by the scarcity of Empididae, Symphyta, Ichneumonidae and Formicidae. The major determinants of the composition of the arboreal fauna are discussed, including biogeographical and historical constraints, rainforest mesoclimate and host phenology, host architecture and biochemistry, and intrinsic composition of the foliicolous fauna. The faunistic composition of this subtropical rainforest tree species exhibits several features common to both temperate trees (such as the high numbers of homopterans and spiders and the limited populations of arboreal ants) and tropical rainforest trees (such as the large beetle populations and the high orthopteran biomass). Introduction The potientially rich and diverse arthropod fauna from Australia remains largely undiscovered and its systematics is still fragmentary (Taylor 1983). This is particularly true of herbivores and of species associated with arboreal habitats (Woinarski and Cullen 1984). Forest entomology in Australia has been focused mainly on pests associated with two genera of trees, dominant in Australian ecosystems: Eucalyptus and Acacia (e.g. Froggatt 1923; Morrow 1977; Carne and Taylor 1978; New 1979, 1984; Van den Berg 1980; Ohmart et al. 1983b). Other Australian native trees and their associated fauna have received little attention from entomologists (e.g. Froggatt 1923; Woinarski and Cullen 1984; Andersen and New 1987) and even fewer studies are relevant to canopy arthropods associated with Australian rainforest trees (e.g. Lowrnan 1985). The aims of the present study were to record the arthropod fauna foraging within the crowns of the rainforest tree Argyrodendron actinophyllum Edlin (i.e. the fauna 'associated with' A, actinophyllum) and to assess the ecological features of this arboreal community. This global approach was chosen because Moran and Southwood (1982) showed that trees support a rich arthropod fauna, consisting of species of differing food habits, commonly classified by ecologists into a system of arboreal guilds. Space limitations do not allow presentation of comprehensive checklist of arthropods collected in the crowns of the host tree studied. Such a checklist does, however, exist (Basset 1989) and is available from the author on request. The taxonomic composition of the arboreal fauna is examined here at 0004-959X/91/020171$10.00