Prasophyllum castaneum (Chestnut Leek-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)

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

Prasophyllum castaneum (Chestnut Leek-orchid)

2. National Context

The species is endemic to Tasmania. The species is currently listed as endangered under the EPBC Act and the Tasmanian Threatened Species Protection Act 1995.

3. How judged by TSSC in relation to the 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

There is no quantitative data available against this criterion.

Criterion 2 - Geographic distribution

The species is known from two populations. The area of occupancy is 3ha. The extent of occurrence is 10km2. Data pertaining to decline or fluctuation in the population size or habitat is, however, not available.

Therefore, the species is not eligible for listing under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

A total of 40 mature individuals has been recorded during dedicated field surveys. However, continuing decline in the area, extent and quality of habitat, the number of populations and the number of mature individuals has not been identified as an ongoing threat to the species.

Therefore, the species is not eligible for listing under this criterion.

Criterion 4 - Population size

The number of mature individuals is extremely low with the population recorded to number 40 mature individuals during dedicated field surveys.

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.

4. Conclusion

The number of mature individuals (40) that has been recorded in dedicated field surverys is extremely low. The geographic distribution of the species is also very restricted, it having an area of occupancy of 3ha and extent of occurrence of 10km2. The species is eligible for listing as critically endangered under criterion 4.

5. Recommendation

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

Prasophyllum castaneum (Chestnut Leek-orchid)