Caladenia sp. aff. venusta (Kilsyth South Spider-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

Caladenia sp. aff. venusta (Kilsyth South Spider-orchid)

2. National Context

The species is endemic to Kilsyth South, Victoria.

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

No data is available against this criterion.

Criterion 2 - Geographic distribution

The species has a very restricted geographic distribution having an area of occurrence estimated at 2ha and area of occupancy estimated at 1ha. The species is known from a single location and a decline is projected due to the proposed residential development of the site.

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

Criterion 3 - Population size and decline in numbers or distribution

The observed population is very low, totalling 23 individual plants. This figure is based on survey work and observations by the nominator over several years ('nearly a decade'). A decline in the number of individuals, area of occurrence and area of occupancy is projected on the basis of proposed residential development for the site and its geographic distribution is thus precarious for the survival of the species.

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

Criterion 4 - Population size.

The observed population is extremely low, totalling 23 individual plants. This figure is based on survey work and observations by the nominator over several years.

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

Criterion 5 - Probability of extinction in the wild

The probability of extinction in the wild has not been calculated.

4. Conclusion

The total population is extremely small, its geographic distribution is very restricted and precarious for the survival of the species and located at a site currently allocated for residential development. The species is eligible for listing as critically endangered under criteria 2, 3 and 4.

5. 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:

Caladenia sp. aff. venusta (Kilsyth South Spider-orchid)