-We sampled scorpions in a systematic survey of 294 sites representing the major landform types across the arid Pilbara region of north-western Australia, an area of ca. 179,000 km 2 . We trapped two species of Isometroides, 10 of Lychas and 10 of Urodacus. All species were undescribed except one (U. megamastigus). Patterns of occurrence were similar to those found previously in arid Western Australia, in that temperature and soil characteristics seem to infl uence scorpion distributions; however, there were only weak correlations between species richness and sandiness of the soil, water availability, and annual temperature. In a classifi cation of the sample sites based on occurrence of scorpion species, the major division in the dendrogram was associated with topographic and soil variables, while annual temperature, soil depth, ruggedness, total K and the presence of Acacia species were the fi ve variables (of the 25 available) providing the best fi t with the site matrix. Much more information about the biology and ecology of individual species will be needed in order to interpret these patterns confi dently.

-Ground-dwelling spiders were sampled at 304 quadrats in 24 survey areas chosen to represent the geographical extent and diversity of terrestrial environments in the Pilbara region of Western Australia, an area of approximately 179,000 km 2 . Only taxa that were primarily ground-dwelling and were taxonomically robust were identifi ed to species level. A total of 375 species comprising 14 families was recorded. The families Salticidae (93 species), Zodariidae (71 species) and Oonopidae (70 species) showed marked species-level radiation. After excluding quadrats that were burnt or fl ooded during the sampling period, the distribution data of 375 species from 294 quadrats were analysed, with an average of 12.9 (SD = 6.8) species per quadrat. Singletons (species recorded at only one quadrat) constituted 26% (98 species) of the total number of species, and were found more frequently in the Roebourne and Fortescue subregions. Species assemblages were indistinct at the quadrat level, but signifi cant clustering occurred when the data were pooled into the 24 survey areas. The arrangement of the survey areas on an MDS ordination plot was analogous with their spatial positions on a map, in particular the division into a northern and southern Pilbara with the Fortescue cluster running in between. This division was also evident with a number of strong allopatric species distributions. The separation of the survey area clusters was correlated with variation in annual precipitation, latitude and dry season precipitation. Given the sporadic nature of rain events in the Pilbara bioregion and the limitations of the climatic data, however, some caution is advised in interpreting these results.

No abstract

-The ant fauna of the Pilbara Bioregion, which covers an area of ca. 179,000 km 2 , is reviewed. During surveys undertaken between May 2003 and September 2006, ants were one of the taxonomic groups to receive special attention. The total number of ant species recorded from 24 survey areas was 245, and these were placed in 37 genera and 9 subfamilies. Ants recorded from single quadrats ('singletons') accounted for 18.8% of the species. The most speciose genera were Camponotus (36 spp.), Iridomyrmex (31 spp.) and Melophorus (30 spp.). Based on current knowledge, 43% are purely Eremaean, 8% are primarily Bassian, 6% are primarily Torresian, nearly 17% occur over two of Australia's three biogeographic divisions, and 25% are widespread over all three. At a quadrat level, there was no signifi cant correlation between richness and any environmental variable, while clustering analysis revealed weak environmental correlations with ant assemblage composition. The classifi cation at survey area level identifi ed six groupings of ants; three climatic variables associated with these groupings were identifi ed, namely annual temperature, precipitation in the coldest quarter of the year and annual precipitation.

-117 zodariid species were recorded from the Wheatbelt region of Western Australia after 12 months ot continuous pit trapping ,lt 306 quadrats (12 landform types at each of 24 survey areas), with an average richness of 3,98 per quad rat. Analysis of the data at the landscape scale showed no significant relationships between species composition and substrate at each quadrat, other than a weak north-south changeover in composition. Strongly localised patterns of composition at the species level were overt, with a high proportion of short-range endemic species. However a regional-scale analysis (of species compositional patterns by survey area) showed a distinct relationship with precipitation in the driest period. Also, species richness for each survey area and each landform type revealed a correlation between low richness and both high rainfall and low drainage. Greater knowledge of zodariid ecology is required to determine the possible influence of microhabitats on species composition, INTRODUCTIONThe Zodariidae are medium-sized spiders, currentlv divided into five subfamilies and