Canberra Spider Orchid (Arachnorchis Actensis)
The Canberra Spider Orchid (Arachnorchis actensis) is found only in the ACT.
It only occurs within small areas on Mt Ainslie and Mt Majura in Canberra Nature Park, on Department of Defence land within the Majura Valley, and in Kowen Escarpment Nature Reserve.
The orchid was declared an endangered species in the ACT in April 2005. The species is now listed as critically endangered under the Nature Conservation Act 2014 and the Environment Protection and Biodiversity Conservation Act 1999. It also has special protection status in the ACT.
The Canberra Spider Orchid is a small terrestrial orchid (40–90mm) that may grow as a single plant or in small groups. It has a densely hairy leaf (between 4–9cm long and 0.6-0.8cm wide) that is dull green with a purple-blotched base. The flowers are solitary and grow to 12–20mm in diameter. The base of the flower is greenish and is heavily marked with red–crimson lines.
The Canberra Spider Orchid is a seasonal perennial. It remains as a dormant underground tuber over summer and emerges from the ground following good rains in late autumn or early winter. Flower buds appear in late winter or early spring and flower from late September to mid-October. Flowers imitate female insects to attract the Thynnine Wasp, which then transfers the pollen to other flowers. The Canberra Spider Orchid needs a mycorrhizal fungus to germinate and to supply it with adequate carbon and nutrients, especially phosphorus.
Conservation threats
Urban development and agricultural practices have resulted in the loss, degradation and fragmentation of the Canberra Spider Orchid’s woodland habitat. As a result, populations of the species are small. Poor genetic diversity and the life history of the species (including short flowering period, dependence on a single sub-family of wasps for pollination and association with soil fungi) is likely to leave it vulnerable to the impacts of climate change, disturbance and disease.
The most common disturbances to the habitat of the Canberra Spider Orchid include animal trampling, grazing pressure, the development of infrastructure, and bushfire.
Conservation objectives
- Protect sites where the species is known to occur in the ACT from unintended impacts.
- Manage the species and its habitat to maintain the potential for evolutionary development in the wild.
- Improve the long-term viability of populations through management of woodlands to increase habitat area and connect populations.
- Expand the range of the species in the ACT by identifying suitable habitat and establishing new populations by translocation.
- Improve understanding of the species’ ecology, habitat and threats.
- Strengthen stakeholder and community collaboration in the conservation of the species.
Conservation actions
Priority management actions for the orchid include to:
- protecting all populations from unintended impacts
- require site management to conserve the species and its habitat
- monitor populations and the effect of management actions
- manage grassland/woodland next to the species’ habitat to increase habitat area or connect populations
- undertake or facilitate research and trials into techniques for increasing the population size and establishing new populations.
- undertake or facilitate research on habitat requirements, techniques to manage habitat and aspects of ecology directly related to the conservation of the species
- promote a greater awareness of, and strengthen community engagement in, the conservation of the species.
More information
Contact
Email environment@act.gov.au or phone Access Canberra on 13 22 81.