No abstract

A pharmacological survey of flora of the Paluma rainforest including 90 species representing 19 families has been carried out. Crude plant extracts have been screened for cytotoxic, antibacterial, antifungal, and antiviral activity, as well as brine shrimp lethality. Of these, 27 extracts exhibited remarkable cytotoxic activity, 23 showed antimicrobial activity, and 7 showed promising antiviral activity. Thus, 53 of the plant species examined showed marked bioactivity in one or more bioassays; a "hit rate" of 59%. These results underscore the phytomedicinal potential of Australian tropical rainforests.

Consumption of terrestrial leaf litter by stream invertebrates is an important process, but little attention has been paid to the influence of leaf diversity on the process. Tropical forests are known to have much greater diversity of plant species than their temperate counterparts, but studies of litter processing in tropical streams have not explicitly addressed this issue. This paper documents the streambed leaf litter composition and diversity of an Australian tropical rain-forest stream and the leaf preferences of consumers in the stream. We hypothesized that there would be high diversity of litter in the stream and that the shredders would have broad preferences, given that litterfall of any one species would occur over a restricted period. Leaf litter was characterized by high species diversity (81 species from one stream reach sampled on two occasions). Leaf consumers (‘shredders’) were associated with a relatively broad suite of leaf species (38 species) and did not indicate clear leaf preferences. However, in a laboratory feeding experiment, using the three most common shredder species and some of the most abundant leaf species in the stream, all shredder species exhibited clear preference for a single leaf species (Endiandra bessaphila). Preference for this and other species was affected by the conditioning age of leaves (i.e. the length of time leaves were exposed to leaching and microbial colonization), with conditioned leaves usually being preferred, and previously non-selected leaves becoming more palatable with conditioning. Thus, different successional stages were more important than the identity of leaf species in determining the distribution of shredders among the leaves.

A revision of the Ficus obliqua—F. rubiginosa complex (Moraceae: Urostigma sect. Malvanthera Corner) is presented. A phenetic analysis of morphometric characters using clustering techniques and multidimensional scaling was used to identify the taxa in this complex. Three taxa are recognised, F. obliqua G.Forst., F. rubiginosa Desf. ex Vent. f. rubiginosa and F. rubiginosa f. glabrescens (F.M.Bailey) D.J.Dixon. Each taxon is redescribed. The epithet glabrescens of F. rubiginosa f. glabrescens is resurrected with a change in status. The data from the pollinator wasps strongly supports the taxonomy, with F. obliqua pollinated by Pleistodontes greenwoodi (Grandi) and F. rubiginosa sens lat. pollinated by P. imperialis Saunders. A key to the species and infraspecific taxa of F. rubiginosa as well as notes and distribution maps are provided for both species.

The crude chloroform bark extract of Syncarpia glomulifera (Myrtaceae) shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of oleanolic acid-3-acetate, ursolic acid-3-acetate and betulinic acid. The relatively large abundance (10% of the crude extract) and high degree of activity of betulinic acid are responsible for the bioactivity of the crude bark extract.