Pterostylis metcalfei (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,Pterostylis metcalfeiD.L. Jones as an ENDANGERED SPECIES on Part 1 of Schedule 1 of the Threatened Species Conservation Act. Listing of Endangered Species is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1.Pterostylis metcalfei D.L. Jones (Orchidaceae) was first described in 1997 and was previously known as Pterostylis sp. aff. russellii (New England) (Bishop 1996, Field Guide to the Orchids of New South Wales and Victoria. University of NSW Press) and also treated as a pale green and white form of Pterostylis decurva (Metcalfe 1987).

2.Pterostylis metcalfei has been described by Jones (1997) (The Orchadian, Vol. 12, No. 6) as: tuberous terrestrial herb growing in small to large colonies. Sterile and fertile plants dimorphic. Rosette separate; leaves 3-5; lamina ovate to oblong-ovate, 9-30 mm long, 7-20 mm wide, dark green, entire; apex obtuse to shortly apiculate; petioles 4-12 mm long, narrowly winged. Flowering parts 10-30 cm tall. Scape slender, wiry, smooth. Cauline leaves 4-6, lanceolate to linear-lanceolate., 15-30 mm long, 4-7 mm wide, erecto-patent, dark green; margins entire; apex acuminate; lowest cauline leaf reduced and closely sheathing. Ovary narrowly oblong-obovoid, 7-9 mm long, green, smooth. Flower solitary, 23-28 mm long, translucent white, striped and suffused with dark green, darkest towards the apex of the galea; galea gibbous at the base then erect before curving forwards; apex of the dorsal sepal decurved. Dorsal sepal 40-52 mm long, 16-20 mm wide, inflated at the base, constricted near the middle, slightly enlarged above the middle before tapering suddenly to a filiform point 7-14 mm long, translucent white with green stripes and suffusions, darker towards the apex. Lateral sepals erect, tightly embracing the galea; sinus protruding in a shallow bulge when viewed from the side, the upper margins horizontal or slightly raised centrally with a central notch when viewed from the front; conjoined part 12-16 mm long, 8-12 mm wide, narrowed to c. 3 mm across at the base, translucent white heavily suffused and lined with green; upper margins dark green and involute, suddenly tapered into free points; free points 22-30 mm long, linear-filiform, involute, erect, held high above the galea, parallel. Petals obliquely lanceolate, 22-32 mm long, 4-6 mm wide, strongly falcate, tapered distally, subacute to acute, central part white, anterior part bright green, distal part darker green or slightly brownish green; flange broadly obtuse, c. 1.5 mm across, flat. Labellum hinged on a basal ligulate claw c. 4 mm long, c. 1.5 mm wide, erect, suddenly curved forwards in the distal third, the distal third protruding prominently through the sinus in the set position; apex of the labellum sometimes touching the galea; lamina broadly oblong-lanceolate to oblong-elliptic, 13.5-17 mm long, 2.5-3.5 mm wide, brown or brownish white, distal third dark brown, brown or greenish brown towards the base; apex obtuse; basal appendage 4-5 mm long, narrow-linear, recurved at right angles just above the middle; apex shortly penicillate. Column 15-17 mm long, bent away from the ovary at about 60o then erect or incurved, green and brown. Column wings oblong-rectangular, c. 8 mm long; basal lobe c. 3 mm long, c. 1.5 mm wide, at an angle of about 50o, inner basal margins incurved, cilliate; apex obtuse; mid-section c. 3 mm long, dark brown; apical lobe linear, c. 1.2 mm long. Anther c. 1.2 mm long, obtuse. Pollinia linear, 1.8-2 mm long, yellow, mealy. Stigma elliptical-scutiform, 4-4.5 mm long, c. 2 mm wide, raised, situated just below the column wings. Capsule not seen.

3. The species is endemic to the New England Tablelands, occurring on soil derived from granite and basalt. It is known from three locations between Wongwibindi and Hernani. One location is reserved within Guy Fawkes River National Park.

4. The risk of extinction is high due to low population numbers and it is also threatened by cattle grazing and trampling. Road maintenance may also adversely impact populations at some locations.

5. In view of 3 & 4 above the Scientific Committee is of the opinion that the species is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Proposed Gazettal date: 05/10/01

Exhibition period: 05/10/01 - 0911/01

Reference:

Metcalfe, P. (1987) in Beadle, N.C.W. (Ed.), Student's flora of north-eastern New South Wales part IV, pp. 1026, University of New England, Armidale.

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Page last updated: 28 February 2011