NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Pomaderris delicata N.G. Walsh & F. Coates (Delicate Pomaderris) (family Rhamnaceae) is described by Walsh & Coates (1997) as follows: ‘shrub 1-2 m high. Young stems pubescent with very sparse, loosely appressed greyish-yellow or rusty simple hairs and dense, greyish-yellow stellate hairs. Leaves elliptic, 13-30 mm long, 5-15 mm wide; base cuneate; margins entire, plane or slightly recurved; apex obtuse to broadly acute; adaxial lamina glabrous, smooth lateral veins not or slightly impressed; abaxial lamina densely pubescent with greyish stellate hairs; midrib with a few appressed, pale or rusty simple or comb-like hairs, sometimes extending onto lateral veins; petiole 3-5 mm long; stipules triangular, acute, 1-2 mm long, caducous. Inflorescence of 20 to >50 flowers, pyramidal, terminal, 1.5-4 cm long, 2-5 cm wide; bracts caducous; pedicels 1.5-3 mm long. Flowers golden-yellow; externally pubescent with sparse to moderately dense, loosely appressed to spreading greyish simple hairs (sometimes very short) and dense, greyish stellate hairs, both hair types less dense on sepals; hypanthium 0.8-1.2 mm in diameter, 0.8-1 mm long; sepals 1.7-2 mm long, spreading; petals 1.7-2 mm long, spathulate; stamens c. 1.5 mm long; anthers 0.9-1.1 mm long; ovary inferior, pubescent with simple and stellate hairs; style glabrous, 1-1.5 mm long, branched in upper to middle third. Fruit ellipsoid to obovoid, 2.5-3.5 mm long, brown; apex obtuse; torus c. equatorial; operculum c. two-thirds pyrene length; seed c. 2 mm long.’ Flowers occur in October and fruits in December (Walsh & Coates 1997).
2. Pomaderris delicata has a close affinity with P. andromedifolia; a species that occurs in close proximity to P. delicata populations, but P. delicata is distinguished by leaves that are generally shorter and not silky on the lower surface. In addition, the upper surface of the leaf of P. delicata is generally smooth, unlike the wrinkled surface of P. andromedifolia. Pomaderris delicata also differs in having stipules that fall before or soon after the expansion of the leaf blade whereas those of P. andromedifolia usually persist for several nodes below the growing tip and are larger (2-4 mm long) (Walsh & Coates 1997).
3. Pomaderris delicata, discovered in 1995, is known from two populations south-west of Goulburn on the Southern Tablelands of NSW (K McDougall pers. comm. 2009). These populations are separated by roughly 30 km and both occur on roadside reserves, adjoining private property and Crown land. No populations are currently known to occur within a conservation area.
4. Both populations of Pomaderris delicata are found in dry sclerophyll forest dominated by Eucalyptus sieberi with a dense shrubby understorey on shallow, rocky soil, derived from Silurian and Ordovician sediments (Walsh & Coates 1997).
5. Pomaderris delicata has a very highly restricted geographic distribution. The two localities from which the species is known represent an extent of occurrence of no more than 12 km2 and an area of occupancy of 8 km2, based on occupancy of two 2 × 2 km grid cells, the scale of assessment recommended by IUCN (2008).
6. The current number of mature individuals for Pomaderris delicata is estimated to be about 120, with a maximum of 270 (K McDougall pers. comm. 2009).
7. Understorey clearing and overgrazing on private property has greatly reduced the size of Pomaderris delicata populations, with much of the land between the two known populations now cleared. ‘Clearing of native vegetation’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
8. The greatest immediate threat to Pomaderris delicata is from roadside damage (e.g. slashing, fire prevention works). For example, half of one population was destroyed by roadwork in late 2007 (K McDougall pers. comm. 2008). Low population numbers and restricted distribution also make the species susceptible to demographic and environmental stochasticity.
9. Pomaderris delicata N.G. Walsh & F. Coates 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 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
(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.
Dr Richard Major
Chairperson
Scientific Committee
Proposed Gazettal date: 16/07/10
Exhibition period: 16/07/10 - 10/09/10
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).
Walsh NG, Coates F (1997) New taxa, new combinations and an infrageneric classification in Pomaderris (Rhamnaceae). Muelleria 10, 27–56.