The Insect Assemblage Visiting the Flowers of the Subtropical Rainforest Pioneer Tree Alphitonia excelsa (Fenzl) Reiss. ex Benth. (Rhamnaceae) Geoff Williams l 2 and Paul Adam 2 1 c/o Department of Entomology, Australian Museum, 6 College Street, Sydney NSW 2000 2 School of Biological Sciences, University of New South Wales, Sydney NSW 2052 Williams, G. and Adam, P. (2001). The insect assemblage visiting the flowers of the subtropical rainforest pioneer tree Alphitonia excelsa (Fenzl) Reiss. ex Benth. (Rhamnaceae). Proceedings of the Linnean Society of New South Wales 123, 235-259. Alphitonia excelsa is a bisexual, protandrous, pioneer rainforest tree. Anthesis and nectar production are diurnal. Populations studied on the Mid-North Coast of New South Wales flower between January and March. Alphitonia excelsa is dependent upon insects for pollen transfer. Flower-visiting insect assemblages are dominated by Hymenoptera, Coleoptera, and especially Diptera but vary over time, and geographically. Most of the visiting insects were 6 mm or less in size. Approximately 200 genera, from 116 families, were recorded from A. excelsa flowers. This fauna comprises taxa that, currently, are known within the region only from A. excelsa, and species shared with other mass-flowering rainforest trees. Aculeate wasps were a conspicuous element of the anthophilous insect fauna visiting A. excelsa in a littoral rainforest remnant at Harrington. Introduced honey bees, Apis mellifera, were active at blossoms at all study sites, but visitation varied over the 3 seasons of study. Manuscript received 15 August 2001, accepted for publication 21 November 2001. KEYWORDS: insect assemblages, biodiversity, Alphitonia excelsa, pollination, subtropical rainforest, rainforest restoration. INTRODUCTION Although Australian rainforests have been subject to an increasing number of ecological studies much recent work has concentrated in the tropics (e.g., Harrington et al. 1997, Laurance 1997, Kitching et at. 2000), and documentation of the biodiversity of subtropical rainforests is still relatively poor. We investigated the insect fauna associated with the flowers of the small to medium-sized pioneer tree Alphitonia excelsa (Fenzl) Reiss. ex Benth. (Rhamnaceae) (Figs. 1, 2). Alphitonia excelsa occurs in the Northern Territory, Western Australia, Queensland, and New South Wales (extending to Mt Dromedary on the far south coast) (Harden 1990). Isolated populations occur inland in the Pilliga Scrub and the Nandewar Ranges (Mt Kaputar National Park) on the New South Wales northern slopes. In New South Wales A. excelsa occurs commonly on the margins of littoral rainforest, in floodplain rainforest remnants, submontane subtropical rainforest, wet sclerophyll forest and also occasionally in dry sclerophyll forest. This distribution indicates that the species is a successful coloniser of a broad range of forest subformations and soil types. Proc. Linn. Soc. N.S.W., 123. 2001
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