Genoplesium littorale - 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, Genoplesium littorale D.L. Jones (Tuncurry Midge Orchid) 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. Genoplesium littorale D.L. Jones (family Orchidaceae) is a terrestrial herb of the Midge Orchid genus. It was described by Jones (2006), under the nomenclatural synonym Corunastylis littoralis, as follows: “Leaf 100-250 mm long; free part 10-18 mm long, ending below flowers. Spike 10-30 mm tall, 5-30 flowered. Flowers moderately crowded, semi-nodding, 5 x 4 mm, green with purple-brown labellum. Dorsal sepal 3.8 x 2.5 mm; margins hairless; apex sharply pointed. Lateral sepals deflexed, divergent, 4.5 x 1 mm; base humped. Petals 3 x 0.8 mm, spreading; margins hairless; apex sharply pointed. Labellum stiffly hinged, 2.5 x 0.8 mm, oblong, fleshy; margins hairless; apex pointed and recurved. Callus extending nearly to labellum apex.”

 

2. Genoplesium littorale is also known by the synonym Corunastylis littoralis (D.L. Jones) D.L. Jones and M.L. Clem. (Jones et al. 2002), however, this recent taxonomic change has not been widely accepted, and the name Genoplesium littorale is still the most widely used in NSW.

 

3. Genoplesium littorale is endemic to New South Wales where it is known from only one population in the Tuncurry district. The population occurs on well-drained, open sand ridge sites in low dense heath dominated by Ochrosperma lineare or in sparse shrubland of Monotoca elliptica, Brachyloma daphnoides and/or Leptospermum spp. (Jones 2006; Paget 2008). The life cycle of Genoplesium littorale is not well known, with the above-ground parts dying back after fruiting and the species existing as underground tubers for most of the year. The flowering period is from March to May (Jones 2006).

 

4. Genoplesium littorale has a very highly restricted geographic distribution. Its current area of occupancy is estimated to be approximately 8 km2 (Paget 2008), based on the number of occupied 2 x 2 km grids, the spatial scale for assessment recommended by IUCN (2008). Its extent of occurrence is also estimated to be approximately 8 km2.

 

5. Recent surveys have confirmed that there are at least 700 mature individuals in the population (Paget 2008). Although substantial areas of apparently suitable habitat have been searched without locating the species, Paget (2008) estimated that nearby areas of unsurveyed habitat could support an additional 600-1200 plants.

 

6. Weed invasion and clearing of suitable habitat are major threats to the only known population of Genoplesium littorale. Significant infestations of Loblolly Pines (Pinus taeda) and exotic grasses (e.g. Eragrostis curvula) have become established around the edges and throughout the area in which Genoplesium littorale currently occurs (Paget 2008). The construction of firebreaks and infestations of weeds such as Andropogon virginicus (Whiskey Grass) have resulted in substantial habitat degradation at the location of the Type Specimen for this species (J. Riley pers. comm. June 2008). Further clearing of habitat for the development of residential blocks in the Tuncurry district is also a continuing threat. ‘Invasion of native plant communities by exotic perennial grasses’ and ‘Clearing of native vegetation’ are listed as Key Threatening Processes under the Threatened Species Conservation Act 1995.

 

7. Genoplesium littorale 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.

Dr Richard Major

Chairperson

Scientific Committee

 

Proposed Gazettal date: 31/07/09

Exhibition period: 31/07/09 - 25/09/09

References:

 

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)

 

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

 

Jones DL, Clements MA, Sharma IK, Mackenzie AM, Molloy PJ (2002) Nomenclatural notes arising from studies into the Tribe Diurideae (Orchidaceae). The Orchadian 13, 437-468.

 

Paget A (2008) ‘Results of searches for the Tuncurry Midge-Orchid (Genoplesium littorale, syn. Corunastylis littoralis).’ Report to the NSW Scientific Committee, Sydney.

Page last updated: 28 February 2011