Corybas dowlingii (an orchid) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the orchid Corybas dowlingii D.L. Jones as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act. Listing of endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Corybas dowlingii D.L. Jones is an endemic Australian orchid that has been described by Jones (2004) as follows: "Terrestrial tuberous herb growing in colonies. Leaf cordate to orbicular, 15-35 mm long, 15-35 mm wide, dark green adaxially, slightly reddish pellucid abaxially, apex apiculate. Peduncle c. 1-2 mm long. Floral bract closely sheathing, narrowly ovate, 2.5-5 mm long, 2-3 mm wide, acuminate. Ovary erect, straight or incurved, 4-9 mm long, c. 2-2.5 mm wide. Flower solitary, erect with an incurved dorsal sepal, 26-32 mm long, 14-16 mm wide, dark purplish red with whitish areas in the labellum, sometimes obscurely striped. Dorsal sepal concave, curved throughout, ovate-oblong when flattened, 15-23 mm long, 6-10 mm wide, dark reddish purple faint longitudinal striae, narrowed at base, apex apiculate. Lateral sepals linear-tapered, 2-2.5 mm long, c. 0.5 mm wide, acute, porrect or projected upwards against the base of the labellum. Petals linear-tapered, c. 0.5 mm long, c. 0.3 mm wide, acute, falcate, obtuse, hidden behind the labellum. Labellum much shorter than, and mostly hidden by the dorsal sepal, translucent white with red suffusions on the anterior; labellum tube c. 4 mm long, erect then recurved sharply and expanded into a lamina; lamina oblong-elliptic when viewed from the front, 10-12 mm long, 5-6 mm wide, translucent white with reddish suffusions and some red stippling, with a prominent, deep anterior pocket which has a thick intruding fold on the anterior side, the outer margins strongly revolute, the inner surface mostly smooth, the outer surface smooth or with a few short hispid hairs; callus greatly thickened, strongly folded medially. Labellum spurs c. 3 mm long, deflexed and slightly curved forwards, hollow, tapered, whitish. Column c. 3 mm long, semi-erect, broadest at the base (c. 1.8 mm across), minutely winged, with a thick, prominent, fleshy, red pseudo column-foot. Anther c. 1.2 mm long, c. 0.8 mm wide, with a very short, blunt rostrum. Stigma elliptic, c. 1 mm diam., c. 0.7 mm high, sunken. Pollinarium c. 1 mm long, c. 0.6 mm wide, consisting of four pollinia in two pairs, attached directly to an oblong viscidium c. 0.6 mm long. Pollinia oblong, cream to yellowish, mealy. Flowering period: June to August."

2. Corybas dowlingii is restricted to New South Wales where it is currently known from 4 localities including Port Stephens (2 localities), Bulahdelah and Freemans Waterhole south of Newcastle. These localities encompass a total extent of occurrence less than 1,000 km2. Populations of the orchid at three of these locations occupy areas of less than a few hectares, while one of the populations at Port Stephens occupies approximately 50 ha. The geographic distribution of the species is therefore highly restricted.

3. Corybas dowlingii has been recorded within the local government areas of Cessnock, Great Lakes and Port Stephens. The species has not been recorded within any conservation reserves. One population at Port Stephens is within a local government reserve that is currently zoned for general recreation and residential land uses.

4. Corybas dowlingii forms clonal colonies and typically grows in gullies in tall open forest on well-drained gravelly soil at elevations of 10-200m (Jones 2004).

5. The Bulahdelah population of C. dowlingii includes approximately 3400 plants (Roads and Traffic Authority 2004), while the Port Stephens populations include approximately 15 000 plants (Okada, 2006). The size of the Freemans Waterhole population is unknown.

6. Corybas dowlingii is threatened in New South Wales by a continuing decline as a consequence of clearing, fragmentation, habitat degradation and environmental stochasticity due to its highly restricted geographic distribution and small number of locations. The larger Port Stephens population occurs within a bushland remnant adjacent to urban areas and an active quarry (Okada, 2006). Potential expansion of residential development and the quarry may further reduce the area of remnant habitat. Processes such as rubbish dumping and recreational overuse that are typically associated with urban bushland remnants may further threaten the species at this site. The Bulahdelah population is threatened by proposed roadwork that will result in direct removal of 3% of the known Budahdelah population (Roads and Traffic Authority 2004). Other individuals as yet undetected may become exposed after clearing or excavation works. A further 7-22% of the known Budahdelah population may be impacted due to clearing for the proposed realignment and associated power easement, and 49% of the known and potential habitat for this species at Bulahdelah will be destroyed (Roads and Traffic Authority 2004). 'Clearing of native vegetation' is listed as a Key Threatening Process under the Threatened Species Conservation Act.

7. Corybas dowlingii D.L. Jones is not eligible to be listed as a critically endangered species.

8. Corybas dowlingii D.L. Jones is eligible to be listed as an endangered species as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near 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:

highly restricted

(d) a projected or continuing decline is observed, estimated or inferred in:

(i) an index of abundance appropriate to the taxon
(ii) geographic distribution, habitat quality or diversity, or genetic diversity

Professor Lesley Hughes
Chairperson

Proposed Gazettal date: 09/11/07
Exhibition period: 09/11/07 - 18/01/08

References 

Jones DL (2004) Corybas dowlingii (Orchidaceae), a new species from north-eastern New South Wales.  The Orchadian 14, 418-420.

Okada S (2006) 'The Distribution and Abundance of Callistemon linearifolius and  Corybas  dowlingii at Stoney Ridge Reserve, Soldiers Point NSW'. Report to Port Stephens Council.

Roads and Traffic Authority (2004) Bulahdelah Upgrading the Pacific Highway, Environmental Impact Statement. Technical Paper 7, Ecological Assessment and Species Impact Statement. Roads and Traffic Authority of NSW.