Prasophyllum keltonii (terrestrial leek orchid) - critically endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a FINAL DETERMINATION to list Prasophyllum keltonii D.L. Jones 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.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Prasophyllum keltonii D.L. Jones  (family Orchidaceae) is a terrestrial Leek Orchid. It has a single erect bright green tubular leaf 20-35 cm long (8-15 cm of it free above the point of attachment of the inflorescence stalk) and 3-5 mm wide, often withering at the tip in flowering stage. The inflorescence is a dense spike 5-9 cm long, with 12-22 sessile fragrant flowers, each 7-9 mm across and green or brownish red or purplish with green tinges. The dorsal sepal of each flower is deflexed, ovate to lanceolate, 7.5-8.5 mm long, 4.0-4.5 mm wide, with a recurved acuminate apex, and three darker longitudinal stripes. The lateral sepals are free, erect or recurved, linear-lanceolate, 8.5-10 mm long, c. 2 mm wide, with a non-gibbous base, involute distal margins, and an entire or bidentate apex. Petals are linear-lanceolate, 7.0-8.5 mm long,  c. 1.3 mm wide, projecting forward or spreading, incurved distally, with an obtuse to acute apex. The labellum is shortly stalked, projecting forward to obliquely erect, with an erect apex at right angles to the basal part; the lamina is ovate-lanceolate with a non-gibbous base, 6.5-7.5 mm long, 4-5 mm wide, constricted near the middle and extended into an apical ‘tail’ 3.0-3.5 mm long; the labellum margins are widely flared and smooth. The callus is a broad rectangular plate  c. 3 mm long and wide, green to reddish, with a broad concave base, and margins each forming a raised ridge that flanks a deep central channel, the ridges occasionally confluent at the end to form a horseshoe-like structure. The column is  c. 3 mm long, c. 3.5 mm wide, projecting forward from the end of the ovary. (A full description and line drawings are in Jones 2007).

2. Prasophyllum keltonii D.L. Jones was known, prior to formal publication, as  Prasophyllum sp . aff . canaliculatum (McPhersons Plain, D.L. Jones 19186).

3. Prasophyllum keltonii D.L. Jones  resembles and is related to  P. canaliculatum D.L.Jones. The latter is distinguished by having its reddish-brown flowers less crowded and more neatly arranged on the spike, broader petals, a broadly elliptical labellum with widely flared lateral lobes that taper suddenly inwards at the apex and end in a short erect ‘tail’  c. 2 mm long, and a narrower callus that ends in a narrow channel.

4. In New South Wales, Prasophyllum keltonii D.L. Jones is known from a single population, occurring in a small area known as McPhersons Plain, about 30 km north-west of Cabramurra and about 17 km south of Talbingo, in the Tumbarumba Local Government Area. The known population, which is intermingled with  P. bagoensis D.L. Jones, is recorded as comprising approximately 400 plants, of which about 380 occur on the Brandy Marys State Forest Crown Leases, and about 20 on adjacent private property (P. Branwhite  in litt., 2005). Surveys over six years up to 2005 have found no plants in the adjoining Bago State Forest (P. Branwhite  in litt., 2005). The species is not known to occur in any conservation reserves.

5. The species is known only from a highly restricted and complex habitat on the treeless McPhersons Plain, an area of closely mingled tall wet sphagnum heath, fens, and open heathland adjacent to aquatic sedgelands, at an elevation of 1,100 m a.s.l. (Australian Heritage Database, accessed 1 March 2007). The species apparently has a preference for moderately boggy ground, though not sphagnum-dominated areas, but also occurs on some drier patches (P. Branwhite pers. comm. May 2007).

6. Threats to this species are likely to include environmental and demographic stochasticity due to small population size, grazing and trampling by wild and possibly domestic cattle and horses, rooting by feral pigs, and altered hydrology due to adjacent land uses and climate change. Possible additional adverse processes may include slashing of vegetation for fire asset protection zones, and illegal collection. Rooting by pigs, possibly for orchid tubers, has been observed in the only known colony of the species (P. Branwhite pers. comm. May 2007) on at least one occasion, and pigs are reported to still be able to access the Crown Lease part of the population despite fencing. ‘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’ are listed as Key Threatening Processes under the Threatened Species Conservation Act.

7. Prasophyllum keltonii D.L. Jones 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:

(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
Scientific Committee

Proposed Gazettal date: 28/03/08
Exhibition period: 28/03/08 – 23/05/08

Reference:

Jones DL (2007) Two endangered new species of Prasophyllum (Orchidaceae) from southern New South Wales.  The Orchadian 15  (8): 372-375