Diurus aequalis (a terrestrial orchid) - endangered species listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the terrestrial orchid Diurus aequalis F. Muell. ex Fitzg. as an ENDANGERED SPECIES in Part 1 of Schedule 1 of the Act, and as a consequence, to omit reference toDiurus aequalis F. Muell. ex Fitzg. from Schedule 2 (Vulnerable species) of the Act. Listing of endangered species is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1.Diurus aequalis F. Muell. ex Fitzg. (family Orchidaceae) is described by Jones, D. L. (1993) in Harden, G. (ed). Flora of New South Wales. UNSW Press. Vol. 4. p. 142 as: Terrestrial herb. Leaves 2, linear, 10-20 cm long, 3-4 mm wide, conduplicate. Raceme 20-45 cm high, 2-5 flowered. Flowers golden yellow to orange, usually unspotted, c. 2.5 cm across. Dorsal sepal broad-ovate to circular, 7-10 mm long, 8-15 mm wide, erect. Lateral sepals linear to oblanceolate, 8-13 mm long, 2-3 mm wide, falcate, green. Petals erect, widely divergent; lamina elliptic to circular, 6-10 mm long, 4-6 mm wide; claw 4-6 mm long, green. Labellum 5-6 mm long; lateral lobes narrowly to broadly cuneate, 5-9 mm long, 2.5-5 mm wide; midlobe broad-cuneate when flattened, c. 7 mm wide, ridged along midline; callus of 2 broad, incurved ridges c. 3.5 mm long.

2. The species is known from fewer than 20 small and fragmented populations between Braidwood and the Blue Mountains in the central and southern tablelands of NSW. The species previously occurred in the Liverpool area of western Sydney but has not been located there in over 100 years.

3. Only three populations, containing a total of less than 50 individuals, occur within a conservation reserve, Kanangra-Boyd National Park. The remaining populations are restricted to remnant vegetation along roadsides and within agricultural lands.

4. The species is threatened by loss of habitat and continuing declines in habitat quality due to grazing and road maintenance.

In view of the above the Scientific Committee is of the opinion thatDiurus aequalis F. Muell. ex Fitzg. is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Proposed Gazettal date: 01/11/02

Exhibition period: 01/11/02 - 05/12/02

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Page last updated: 28 February 2011