Pterostylis oreophila (an orchid) - critically endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the orchid Pterostylis oreophila Clemesha as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act. Listing of critically endangered species is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1. Pterostylis oreophila Clemesha (Blue-tongued Greenhood, Kiandra Greenhood) (family Orchidaceae) is a terrestrial orchid, with up to five leaves in a basal rosette before flowering but later arranged loosely along the 20cm tall flowering stems. Leaves are elliptic, to 70mm long and 20mm wide. The flower is solitary, erect, predominantly white with narrow green stripes, somewhat bulky (the hood-like galea being about 2.5 cm long), with a recurved labellum of a distinctive bluish or blue-green (aqua) colour. It flowers from November to January. Detailed descriptions and illustrations are available in Bishop (2000), Clemesha (1974), and Jones (2006).

2. P. oreophila was for some years regarded as a synonym of P. dubia R.Br. until reinstated by Jones (1998), who defined P. dubia as a Tasmanian endemic species and listed morphological differences. Bishop (2000) distinguishes P. monticola by its greenish-brown labellum with a less recurved tip, and P. alpina by its more delicate flowers with strongly back-swept lateral sepals extending well beyond the galea; both these species also favour less water-logged sites.

3. In New South Wales, P. oreophila is known from up to three localities. A number of small colonies, possibly totalling about 50 plants (P Branwhite in litt.) are known from the Kiandra area, within Kosciuszko National Park. A small population of about 12 plants (possibly now extinct) has been recorded from Bago State Forest south of Tumut, and about 30 plants from the adjoining Brandy Marys Crown Leases (P. Branwhite pers. comm. 2007). The known distribution therefore includes parts of the Snowy River, Tumbarumba and possibly Tumut Local Government Areas.

4. P. oreophila is also known from occurrences in the Australian Capital Territory (Brindabella range) and in montane areas of far north-eastern Victoria.

5. P. oreophila is recorded as occurring at altitudes of about 1200 to 1500 m a.s.l., usually in streamside habitats where it grows in thickets of Leptospermum in muddy ground very close to water, and (Jones 2006) less commonly in peaty soils and sphagnum mounds. While perhaps most frequently found in low-light conditions it appears to also be able to tolerate full sun (Clemesha 1974).

6. Threats to this species are likely to include environmental and demographic stochasticity due to the narrow areas of occupancy, small population sizes, and dispersed distribution of populations. Other threatening processes may include rooting by feral pigs; mineral fossicking at some sites; grazing and trampling by cattle and wild horses at some sites; altered hydrology due to adjacent land uses and climate change; inappropriate fire regimes; and possible illegal collection. Several of these processes may have disproportionate impact in the very narrow ecological niche apparently favoured by the species. For example, a population in sphagnum mounds in Bago State Forest is reported as having been destroyed by a hazard reduction burn during unusually dry conditions in 2006 (P. Branwhite pers. comm. 2007). Colonies in prospective State Forest logging areas may be protected by general harvest exclusion prescriptions (especially of riparian areas) but may nevertheless be affected by broader-scale associated processes such as sedimentation and local hydrological changes. 'Alteration to the natural flow regimes of rivers and streams and their floodplains and wetlands', 'Anthropogenic Climate Change' and 'Predation, habitat degradation, competition and disease transmission by Feral Pigs, Sus scrofa Linnaeus 1758' are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act.

7. Pterostylis oreophila Clemesha is eligible to be listed as a critically endangered species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:

Clause 15

The geographic distribution of the species is estimated or inferred to be:

(a)very highly restricted,

and:

(e) (i) the population or habitat is observed or inferred to be severely fragmented; and

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations.

Clause 16

The estimated total number of mature individuals of the species is:

(a)very low,

and:

(e)(i) the population or habitat is observed or inferred to be severely fragmented;

and

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations.


Professor Lesley Hughes

Chairperson

Scientific Committee

Proposed Gazettal date: 09/11/07

Exhibition period: 09/11/07 - 18/01/08


References:

Bishop T (2000) Field guide to the orchids of New South Wales and Victoria. (University of New South Wales Press, Sydney.)

Clemesha SC (1974) A new Pterostylis from southern New South Wales. The Orchadian 4, 100-102.

Jones, DL (1998) Contributions to Tasmanian orchidology 1-9. 7: A taxonomic review of Pterostylis in Tasmania. In: Banks DP (ed.), Australian Orchid Research vol. 3. (Australian Orchid Foundation, Seven Hills, NSW.)

Jones DL (2006) A complete guide to native orchids of Australia including the island territories. (Reed New Holland, Frenchs Forest NSW.)


 

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Page last updated: 28 February 2011