Leionema lamprophyllum subsp. obovatum in the Hunter Catchment - endangered population listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list a population of Leionema lamprophyllum (F. Muell.) Paul G. Wilson subsp. obovatum F.M. Anderson in the Hunter Catchment as an ENDANGERED POPULATION in Part 2 of Schedule 1 of the Act. Listing of endangered populations is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Leionema lamprophyllum (F. Muell.) Paul G. Wilson subsp.  obovatum F.M. Anderson  is not currently listed as an endangered species in Part 1 of Schedule 1 or a critically endangered species in Part 1 of Schedule 1A and as a consequence populations of this species are eligible to be listed as endangered populations.

2. L. lamprophyllum subsp.  obovatum (family Rutaceae) is described in Harden (2002) as a "compact shrub to 2 m high; stems warty, minutely pubescent with stellate and simple hairs. Leaves elliptic to broad-obovate or + circular, 0.3-1cm long, 2-4 mm wide, flat or convex when dry, apex acute to rounded, margins entire or acutely erose near apex, smooth, glabrous, glossy above. Flowers solitary in the axils of terminal leaves and bracts or 1-3 on short peduncles; pedicels minutely bracteolate in lower half. Calyx fleshy, lobes triangular, valvate. Petals 3-4 mm long, white with pink tips on outside, gland-dotted. Cocci spreading, c. 3 mm long, outer angle shortly beaked to minutely apiculate. Flowers late winter to spring." The two subspecies are distinguished from each other by their leaf shape and size. L. lamprophyllum subsp. o bovatum has "leaves + obovate, usually 4-7 mm long".

3. Based on herbarium records (National Herbarium of NSW, NCW Beadle Herbarium, University of New England), L. lamprophyllum subsp.  obovatum occurs mainly south from Tidbinbilla Range in the Canberra area, extending into Victoria. The Hunter Catchment population occurs near Pokolbin, where it is found on a rocky cliff line in a dry eucalypt forest.

4. The Hunter Catchment population of L. lamprophyllum subsp.  obovatum refers to all plants of  L. lamprophyllum subsp.  obovatum occurring in the Hunter Catchment as defined by Australia's River Basins, 1997 (Geoscience Australia). Within the Hunter Catchment, the population is currently located in the local government area (LGA) of Singleton, close to the boundary with Cessnock LGA, and in the Sydney Basin Bioregion (Thackway and Creswell 1995). The Hunter Catchment (Geoscience Australia 1997) includes the Local Government Areas of Cessnock, Maitland, Dungog, Singleton, Muswellbrook, Newcastle, Port Stephens, part of Mid-western Regional, and part of Upper Hunter LGA.

5. The population of L. lamprophyllum subsp.  obovatum in the Hunter Catchment is at the north-east limit of the geographic range for this taxon, approximately 350 km from other known occurrences of the taxon to the south-west. The Hunter Catchment population is considered to be highly genetically isolated due to the distance to the nearest recorded occurrence of this taxon, and the lack of specialised mechanisms for long distance dispersal of seed or pollen (Weston pers. comm.).

6. There is currently only one known location in the Hunter Catchment where L. lamprophyllum subsp.  obovatum is found.

7. The total number of mature individuals of L. lamprophyllum subsp.  obovatum in the Hunter Catchment population is estimated to be very low with only 4 individuals currently known.

8. The Hunter Catchment population of L. lamprophyllum subsp.  obovatum is currently known to occur in Pokolbin State Forest. Given the rocky terrain of the location, forestry activities are not considered to be a threat to the population. There are no records of  L. lamprophyllum subsp.  obovatum from a conservation reserve in the Hunter Catchment. The very low number of plants in the Hunter Catchment population predisposes it to threats associated with environmental and demographic stochasticity.

9. The population of Leionema lamprophyllum (F. Muell.) Paul G. Wilson subsp.  obovatum F.M. Anderson in the Hunter Catchment  is eligible to be listed as an endangered population as, in the opinion of the Scientific Committee it is facing a very high risk of extinction in New South Wales in the near future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:

Clause 19

The population is facing a very high risk of extinction in New South Wales in the near future as, in the opinion of the Scientific Committee, it satisfies any one or more of the following paragraphs and also meets the criteria specified in the following clauses:

(a) it is disjunct or near the limit of its geographic range,
(b) it is or is likely to be genetically, morphologically or ecologically distinct,

Clause 23

The estimated total number of mature individuals of the population is observed, estimated or inferred to be very low.

Associate Professor Lesley Hughes
Chairperson
Scientific Committee

Proposed Gazettal date: 27/4/07
Exhibition period: 27/4/07 - 22/6/07

References: 

Geoscience Australia. Australia's River Basins, 1997.

Harden, G.J. (ed.) (2002) Flora of NSW Revised Edition Volume 2. UNSW, Sydney.

Thackway R, Creswell ID (1995) An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserves System Cooperative Program. Version 4.0. (Australian Nature Conservation Agency: Canberra).