Habitat for the endangered ephemeral Monotaxis macrophylla (Euphorbiaceae) in New South Wales: how do predictions compare with the evidence?

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Context The endangered ephemeral herb Monotaxis macrophylla (Euphorbiaceae) has limited (~211) records throughout its known range in eastern Australia. In New South Wales (NSW), the 127 occurrences are spread over more than half of the state, and for regulatory purposes this has led to 262 Plant Community Types (PCTs) being predicted as suitable habitat for the species in the BioNet Threatened Biodiversity Data Collection (TBDC). Under the Biodiversity Assessment Method currently in use in NSW, Monotaxis macrophylla is to be specifically addressed for any development site where one or more of the 262 PCTs occur. Aims To assess how predicted habitats for Monotaxis macrophylla as shown in the TBDC compare with evidence of occurrence. Methods Examination of all available voucher collections, observations records, and the literature for eastern Australia was undertaken, and reviewed against the New South Wales PCT classification. Key results Monotaxis macrophylla was found to be affiliated with only 15 PCTs in NSW at best, but only 10 of these are currently included in the list of predicted PCTs for the species. The weight of evidence from existing presence data clearly shows that 10 heath and rocky scrub PCTs identified for Monotaxis macrophylla in NSW comprise 121 (95%) of all NSW records. Analysis of records in Queensland against Regional Ecosystems did not identify additional PCT-affiliated vegetation that might also support the species elsewhere in NSW. Conclusions The revised suite of 15 PCTs known or expected to support Monotaxis macrophylla occupies just 14,660 km2 or 1.8% of the State (potentially less if low-confidence PCTs are removed), compared with more than 27,000 km2 or 3.4% for the predicted 262 PCTs. Implications Currently, if any development is proposed within land that supports one or more of the 262 PCTs linked to Monotaxis macrophylla, appropriately timed targeted surveys are required to discount its presence, or it must be assumed to be present. This review has highlighted that predicted habitats should be evidence based by using known presence data, rather than assumed using broad understandings of possible habitat, and regular revision of predicted habitats within regulatory frameworks for all threatened species is recommended.