Corunastylis ectopa (Brindabella Midge-orchid)

Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
6 June 2005

1. Scientific name, common name (where appropriate), major taxon group

Corunastylis ectopa (Brindabella Midge-orchid)

Corunastylis ectopa is conventionally accepted. The species was originally described as Genoplesium ectopum. It was first collected in 1992 and was described in 1999. In 2002, a revision of the genus Genoplesium saw the species described as Corunastylis ectopa.

2. Description

The Brindabella Midge-orchid is a terrestrial orchid which grows to between 10 and 25 centimetres from a single underground tuber. The flowers are either green and reddish-purple or wholly reddish-purple.

3. National context

The Brindabella Midge-orchid is endemic to the Australian Capital Territory. It is currently restricted to a single site in the Brindabella Ranges with a population of less than 100 plants. Despite several searches being carried out in the region, further populations have not been found. The Brindabella Midge-orchid has recently been listed as an endangered species in the ACT under the Nature Conservation Act 1980.

EPBC Act criteria.

TSSC judges the species to be eligible for listing as critically endangered under the EPBC Act. The justification against the criteria is as follows:

Criterion 1 - Decline in numbers

The Brindabella Midge-orchid is known from a single site in the Brindabella Range in the ACT at an altitude of 980 m. The total number of plants in 1999 was estimated at 70, and at last count (February 2004, following bushfires and drought conditions) 35 plants were observed. The population occurs within 10 m of a road embankment and plants are known to have been lost in the past by small landslides; the total magnitude of losses is not known. In 2003, the Canberra bushfires destroyed much of the stabilising vegetation from the site making the population more susceptible to the threat of small landslides. The population remains under threat from erosion of the embankment, and possible future roadworks such as road widening or realignment, and bulldozing of new drainage lines and firebreaks. Although the 2004 population size is 50% less than in 1999, this could be due to natural variability associated with drought. The relevance of this change is therefore difficult to assess.

The species is not eligible for listing under this criterion.

Criterion 2 - Geographic distribution

The Brindabella Midge-orchid occurs in a single known population of 35 plants with an area of occupancy of approximately one hectare. The total number of plants in 1999 was estimated at 70, and at last count (February 2004, following bushfires and drought conditions) 35 plants were observed. Small landslides and erosion of the embankment on which the population occurs are known to have caused past population reductions. These threats are likely to cause a continuing decline in the area of occupancy and the number of mature individuals.

Its geographic distribution is precarious for the survival of the species and is very restricted. Therefore, the species is eligible for listing as critically endangered under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

The Brindabella Midge-orchid is known from a single site in the Brindabella Range with a population of 35 individual plants in 2004. The population occurs within 10 m of a road embankment and plants are known to have been lost by small landslides. In 2003, the Canberra bushfires destroyed much of the stabilising vegetation from the site making the population more susceptible to the threat of small landslides. Additional threats to the Brindabella Midge-orchid include future roadworks such as road widening or realignment, and bulldozing of new drainage lines and firebreaks.

Small landslides are likely to cause an ongoing decline in the number of plants, and the proximity of the population to the edge of the road makes its geographic disbribution precarious for its survival, unless measures are taken to abate this threat.

Therefore the species is eligible for listing as critically endangered under this criterion.

Criterion 4 - Population size

The estimated total number of mature individuals is extremely low - 35 plants were observed in 2004.

Therefore, the species is eligible for listing as critically endangered under this criterion.

Criterion 5 - Probability of extinction in the wild

There is no quantitative data available against this criterion.

5. Conclusion

The Brindabella Midge-orchid is known from a single site in the Brindabella Range in the ACT and occurs on an embankment only 10 m from a road. The total number of individuals is extremely low and at last count (February 2004, following bushfires and drought conditions) 35 plants were observed. The geographic distribution is very restricted and is precarious for the survival of the species. With the increased threat from erosion on the embankment due to the loss of stabilising vegetation, and possible future roadworks such as road widening or realignment, and bulldozing of new drainage lines and firebreaks, it is likely to undergo a further decline in population size.

The species is eligible for listing as critically endangered under criteria 2, 3, and 4.

6. Recommendation

TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by including in the list in the critically endangered category:

Corunastylis ectopa (Brindabella Midge-orchid)

Publications used to assess the nomination

Jones, D.L. (1999). Genoplesium ectopum (Orchidaceae), an endangered new species from the Australian Capital Territory. The Orchadian 12(12): 570-573.

Jones, D.L., Clements, M.A., Sharma, I.K., Mackenzie, A.M. and Molloy, B.P.J. (2002). Nomenclatural notes arising from studies into the Tribe Diurideae (Orchidaceae). The Orchadian 13(10): 437-468.

Conservation advice

The Brindabella Midge-orchid only occurs in the ACT (Australian Capital Territory Natural Resource Management region). The species is a seasonal perennial, shooting from a dormant underground tuber. It grows on a steep north-facing slope with sparse shrub cover in tall Eucalyptus radiata forest, extending onto a roadside verge. The soil is a stony brown loam over shale derived from the Nungar Beds. It does not occur within a conservation area.

Key threats to the Brindabella Midge-orchid include: erosion due to the loss of stabilising vegetation, possible future roadworks such as road widening or realignment, and bulldozing of new drainage lines and firebreaks.

The priority recovery and threat abatement actions required for this species are:

  • protect the site where it is known to occur from direct physical disturbance;
  • incorporate conservation measures into relevant Management Plans; and
  • undertake regular monitoring and further research to collate data on recruitment and better understand threats.

This list does not encompass all actions that may be of benefit to this species, but highlights those that are considered to be of the highest priority at the time of listing. Longer term issues that should be considered in broader landscape, regional and or recovery planning include establishing either an ex situ and/or additional population in the wild.

Priority for the development of recovery plan: High. No Recovery Plan is currently in place for the Brindabella Midge-orchid.