Identification Key
To facilitate fast and secure identification, increase the capabilities of biosecurity staff, and reduce the risk of weed incursions, we have developed an interactive digital identification key to the propagules of an initial priority list of 43 species of Asteraceae. Species on the list were selected based on the frequency of their interception by Australian biosecurity officers, difficulties with identification experienced by DAWR staff, and the Northern Australia Quarantine Strategy’s target list of existing or emerging risks, which in turn is informed by overseas survey work. Additional species will be added to the key in the future.
The key is available online at http://keys.lucidcentral.org/keys/v3/daisy_fruit. Built with Lucid v. 3.5 (Identic 2014), it uses 30 morphological characters visible under a dissecting microscope or strong hand lens, such as dimensions, shape, surface structure and color of the propagule, or pappus type and length. To avoid overwhelming the user with irrelevant choices, some characters are dependent on others and only become available once the user has made the relevant selection; choosing a pappus type may, for example, make available characters only applying to that type. Characters are illustrated with diagrams and example images.
All species are illustrated with at least one propagule image. Species’ profiles present information on native and introduced range, weed status in Australia, ecology, nomenclature, and remarks on diagnostic characters. Finally, hyperlinks are provided to the species’ entries in the online data portals Global Biodiversity Information Facility (www.gbif.org), Atlas of Living Australia (www.ala.org.au), Global Invasive Species Database (iucngisd.org/gisd), and Invasive Species Compendium (www.cabi.org/isc).
One of the main advantages of multi-access digital keys over traditional dichotomous keys is that such keys allow users to select diagnostic characters that they have available and can describe confidently, rather than requiring users to answer questions in a fixed order (Edwards and Morse Reference Edwards and Morse1995). This is of particular importance in the present case of Asteraceae propagules, as they may be incomplete when discovered (e.g., if the pappus has broken off).
Collections Research
All character data underlying the key were scored from expertly identified herbarium specimens to make the work reproducible and allow corrections should one of the specimens be reidentified in the future. Most of the voucher specimens are housed by the Australian National Herbarium (CANB), but loans were obtained from other herbaria to complement CANB’s holdings. Two herbaria (GOET, HBG) were visited to study specimens that could not be obtained on loan within the time frame of the project. Without the specimens held by these institutions, it would have been considerably more difficult to obtain detailed data on the morphology of all species, as fieldwork on several continents would have been required. This demonstrates the value of biodiversity collections as a resource for research (Suarez and Tsutsui Reference Suarez and Tsutsui2004).
Acknowledgments
The authors thank David Albrecht for testing the key and making suggestions for improvement, Lindy Cayzer for support and helpful discussions, Brook Clinton for technical assistance, Lydia Guja and Rodney May for their contributions to project development, and the herbaria of the University of Göttingen (GOET), the Biozentrum Klein-Flottbek (HBG), the Royal Botanic Gardens Kew (K), and the Royal Botanic Gardens Victoria (MEL) for making specimens available for study. Two reviewers provided constructive criticism that helped improve an earlier version of the paper. The project was cofunded by the Australian Government, DAWR.
