Overlaying the State of South Australia’s Protected Areas boundary data (‘Conservation Reserve Boundaries’; data.sa.gov.au) with the Interim Biogeographic Regionalisation for Australia (IBRA Version 7; environment.gov.au) layer indicates that 73.2% of the total protected area (excluding Indigenous Protected Areas) in South Australia lies in the arid biogeographic regions of Great Victoria Desert (21.1%), Channel Country (15.2%), Simpson Strzelecki Dunefields (14.0%), Nullarbor (9.8%), Stony Plains (6.6%), Gawler (6.0%), and Hampton (0.5%). The total biogeographic-region area covered by the remaining Conservation Reserves amounts to 26.2% (Murray Darling Depression 10.0%, Riverina 4.8%, Flinders Lofty Block 3.3%, Eyre Yorke Block 3.1%, Broken Hill Complex 2.8%, Naracoorte Coastal Plain 1.2%, Southern Volcanic Plain 1.2%, and Kanmantoo 0.4%). Background blue shading indicates relative average annual rainfall (data from bom.gov.au). Comparing the distribution of the Conservation Reserves with maps of South Australia’s plant species richness and endemicity from Guerin et al. (2016) demonstrates clearly that most of the protected-area network within the state therefore covers regions of lowest plant richness and endemicity (Suppl. material 1: Fig. S1).