Prasophyllum fuscum R.Br. sens. str. - critically 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 Prasophyllum fuscum R.Br. sens. str. as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act, and as a consequence, to omit reference to Prasophyllum fuscum R.Br. from Part 1 of Schedule 2 (Vulnerable species) 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 fuscum R.Br. sens. str. (family Orchidaceae) is a terrestrial herb of the Leek Orchid genus described by David L. Jones, pers. comm. March 2008 as follows: “Leaf 150-400 x 4-6 mm. Inflorescence 300-450 mm tall. Spike 70-120 mm long, 10-30-flowered. Flowers moderately crowded, 9-13 x 5-7 mm, greenish brown to reddish brown, lightly scented. Dorsal sepal 8.5-9.5 x 3-3.5 mm, pointed. Lateral sepals free, 8.5-10 x 2 mm, recurved, parallel, pointed. Petals 7-7.5 x 1.5 mm, projecting forward to spreading, pointed. Labellum sharply recurved near the middle, 8-9 x 4.5-5 mm, constricted and ending in a relatively short midlobe, often slightly crinkled. Callus shiny, prominently raised, with irregular margins, extending beyond labellum bend onto the midlobe.” Previous descriptions of “Prasophyllum fuscum” (e.g. Bernhardt & Rowe 1993; Bishop 2000; Jones 2006) refer to a broadly circumscribed interpretation of that name, which includes at least two taxa and therefore do not accurately describe P. fuscum sens. str. Copeland 2008 The above description is based on the Type specimen and specimens collected recently near Wilton, New South Wales (Copeland pers. comm. 2008).

 

2. Prasophyllum fuscum was first described by Robert Brown in 1810 from “Moist meadows towards George's River”. Since then, the name Prasophyllum fuscum has been incorrectly applied to many closely related species throughout Victoria, Tasmania and New South Wales (e.g. Guyra, Barrington Tops and the Blue Mountains). Prasophyllum fuscum, in the strict sense, is now believed to be endemic to an area south-west of Sydney. The species is very similar to Prasophyllum uroglossum but occurs further north and differs by having a much shorter midlobe on the labellum and by having the callus extending well onto the midlobe. Prasophyllum pallens, which has also been confused with Prasophyllum fuscum, is known only from the Blue Mountains and can be distinguished by having paler-coloured flowers with a musty smell.

 

3. Prasophyllum fuscum is endemic to New South Wales where it is currently known only from the upper catchment of the Georges River, south-west of Sydney. The only recent collection of the species is from a roadside in the Wilton district. The population grows in moist sandy soil over sandstone amongst sedges and grasses in an area that appears to be regularly slashed by the local council (Copeland 2008). Flowers have been observed in mid spring although the flowering time may vary depending on environmental conditions such as recent rainfall. Like most terrestrial orchids, the species is believed to be semi or fully dependent on a mycorrhizal symbiont.

 

4. Prasophyllum fuscum is not known to occur in any conservation reserves.

 

5. Prasophyllum fuscum has a very highly restricted geographic distribution. It is currently known from a single population and has an area of occupancy of no more than 4 km2 based on the species occupying a single 2 x 2 km grid, the spatial scale recommended for assessing areas of occupancy by IUCN (2008).

 

6. The total population of Prasophyllum fuscum, based on a single observation in 2007, is estimated to be approximately 25 mature individuals.

 

7. Prasophyllum fuscum may be threatened by roadside maintenance activities, where these involve habitat disturbance and slashing during the season of active growth, flowering and fruiting. Illegal collecting of plants by orchid enthusiasts may also threaten the species. The very highly restricted distribution and extremely low number of mature individuals also expose the species to stochastic events that may threaten its persistence.

 

8. Prasophyllum fuscum R.Br. sens. str. 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 either:

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

(i) an index of abundance appropriate to the taxon, or

(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

 

Clause 16

The estimated total number of mature individuals of the species is:

(a) very low,

and either:

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

(i) an index of abundance appropriate to the taxon, or

(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

 

Clause 17

The total number of mature individuals of the species is observed, estimated or inferred to be:

(a) extremely low.

 

 

Dr Richard Major

Chairperson

Scientific Committee

 

Proposed Gazettal date: 18/12/09

Exhibition period: 18/12/09 – 05/03/10

 

References

 

Bernhardt P, Rowe RR (1993) Prasophyllum. In ‘Flora of New South Wales. Vol.4 ’. (Ed. GJ Harden) pp. 155-163 (University of New South Wales Press: Sydney)

 

Bishop T (2000) ‘Field guide to the orchids of New South Wales and Victoria. 2nd edition’ (University of New South Wales Press: Sydney)

 

Copeland LM (2008) ‘Clarification of the taxonomy, and a reassessment of the conservation status, of Prasophyllum fuscum, P. uroglossum and P. pallens (Orchidaceae) in NSW’ Report to the NSW Scientific Committee, Sydney.

 

IUCN (2008) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland). (http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf).

 

Jones DL (2006) ‘A complete guide to native orchids of Australia including the Island Territories’. (Reed New Holland: Sydney)

Page last updated: 28 February 2011