Prasophyllum innubum (terrestrial orchid) - critically endangered species

Final Determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a FINAL DETERMINATION to list the terrestrial orchid Prasophyllum innubum 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.

The Scientific Committee has found that:

1. Prasophyllum innubum D.L. Jones is a terrestrial Leek Orchid. It has a single erect bright green tubular leaf 20-50 cm long (7-15 cm of it free above the point of attachment of the inflorescence stalk) and 3-4 mm wide, often withering at the tip in flowering stage. The inflorescence is a loose spike 5-8 cm long, with 6-20 subsessile flowers, each 6-9 mm across and brownish green with white and purplish petals and a white or pink labellum. The ovaries are obovoid, oriented at about 45o to the rachis, 4-6 mm long, 2.5-3 mm wide, green and shiny. The dorsal sepal of each flower is projected forward to decurved, oblong- or ovate-lanceolate, 5-6 mm long, 3.0-3.5 mm wide, with an obtuse apex. The lateral sepals are connate, more or less erect, forming a synsepalum behind the labellum, each sepal linear-lanceolate, 5-6 mm long, c. 2 mm wide, straight, with involute margins, and an entire blunt apex. Petals are incurved to spreading, linear, 6-7 mm long, 1.0-1.3 mm wide, with a pink or purplish central stripe. The labellum is sessile, projecting forward in the proximal half, sharply recurved in the distal half; the labellum lamina is oblong-elliptic when flattened, 7-9 mm long, 3.0-3.5 mm wide, white or pink, with a non-gibbous base and a broadly obtuse to apiculate apex; the labellum margins are entire proximally, irregularly undulate or finely toothed distally. The callus is more or less oblong tapered, 5-6 mm long 1.5-2.0 mm wide, green or whitish or pink distally, wit an irregular truncate to emarginate apex. The column is c. 2.5 mm long, c. 3.5 mm wide, projecting forward from the end of the ovary, mostly purple, with a truncate apex (A full description and line drawings are in Jones 2007).

2. Prasophyllum innubum D.L. Jones has been known prior to formal publication as as Prasophyllum ‘innubum’ D.L. Jones MS (P.G. Branwhite 297), P. aff. alpestre, and as ‘P. aff. alpestre – Brandy Marys #1’.

3. Prasophyllum innubum D.L. Jones resembles and is related to P. mimulum D.L. Jones, and to P. alpestre D.L. Jones which occurs in the same area. Prasophyllum innubum D.L. Jones is distinguished from these species by its much smaller self-pollinating flowers, short blunt dorsal sepal, short blunt lateral sepals that are usually connate over their whole length, short narrowly linear petals and a relatively narrow oblong-elliptic labellum with the oblong callus extending more than halfway along the lamina (Jones 2007). In addition, P. alpestre often has crenulate (crinkly-edged) petals, and tends to occur on somewhat drier sites, including in grassy habitats (D. Rouse pers. comm., 2007).

4. In New South Wales, Prasophyllum innubum D.L. Jones is known from a single population comprising about seven small colonies (Jones 2007), totalling about 400 individuals (Jones 2007, P. Branwhite in litt.), from a small area about 30 km north-west of Cabramurra and about 17 km south of Talbingo, in the Tumbarumba Local Government Area. The species occurs in Bago State Forest and apparently also on adjacent Crown forestry lease and private freehold. The species is not known to occur in any conservation reserves.

5. The species is known only from a highly restricted streamside habitat and Sphagnum hummocks, and rarely on adjacent grassy flats, at altitudes of 1150-1180 m asl. It flowers in January and February.

6. Apparent threats operating on this species include grazing, trampling and drainage disturbance of habitat by cattle and/or horses (confirmed for one site, P. Branwhite in litt. 2005), and removal of creek bank soil and disturbance of habitat by mineral fossickers (confirmed for one site, P. Branwhite in litt. 2005). Potential threats also include environmental and demographic stochasticity due to small population size, hydrological change through climate change and/or changes in use and management of adjacent land, off-road vehicle activities, horse trail-riding, and illegal collection. ‘Anthropogenic Climate Change’ and ‘Alteration to the natural flow regimes of rivers and streams and their floodplains and wetlands’ are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act.

7. Prasophyllum innubum 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: 28/03/05 – 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

Page last updated: 28 February 2011