Zieria obcordata subsp. obcordata

Zieria obcordata subsp. obcordata View in CoL

Description

Branchlets not prominently glandular–verrucose or with scattered glandular tubercles. Cocci smooth, glandular but not prominently glandular–verrucose.

Distribution

Confined to a number of subpopulations near Crackerjack Rock, west of Bathurst, Central Tablelands , New South Wales .

Conservation assessment

Zieria obcordata subsp. obcordata is localised and known from several subpopulations that occur over a limited area that is ~ 3.5 km across. The species has been extensively surveyed in the area through the Saving Our Species program. The area is heavily disturbed and though stock and wildlife have been excluded from some plants, these are an ongoing threat to plants and successful recruitment outside the small, protected areas. The subspecies is found entirely on private property, in heavily disturbed areas and therefore not secure in the long term. Future threats include changes of land use, such as increased stocking or clearing, changes in conservation management and climate change. The overall population likely constitutes slightly more than 250 adult individuals scattered over a wide area. Shelly et al. (2021) indicated that the subspecies had significant reduction in plant numbers (an average loss of 82% of plants at selected sites) due to drought conditions from 2017 to 2019. Significant recruitment (thousands of seedlings) has occurred following recent wet conditions ( Shelly et al. 2021) but the success rate of these seedlings is not known. The EOO of this subspecies is 4 km 2 and the AOO is 16 km 2 ( Table 3). The assessment below is based on adult plants.

As far as could be determined, Zieria obcordata subsp. obcordata meets the criteria for listing as a Critically Endangered Species under the New South Wales Biodiversity Conservation Act 2016 (see also IUCN Species Survival Commission 2012; IUCN Standards and Petitions Committee 2024). According to the New South Wales Biodiversity Conservation Regulation 2017, Clause 4.3 (Restricted Geographic Distribution of Species and Other Conditions; equivalent to IUCN Standards and Petitions Committee 2024, Criterion B), the subspecies qualifies for this status due to its extremely limited range (EOO <100 km ²) and severely fragmented population, consisting of one main population with several small subpopulations. Additionally, ongoing decline is evident in both the number of subpopulations and habitat quality. The species primarily grows in a rural setting on private land with minimal formal protection, and its survival is further threatened by herbivory and invasive weeds, both of which are well documented.

In addition, Zieria obcordata subsp. obcordata meets the requirements to be listed as an Endangered Species under Clause 4.4 (Low numbers of mature individuals of the species and other conditions; equivalent to IUCN Standards and Petitions Committee 2024, Criterion C) as there are probably between 250 and 500 mature individuals, the number of individuals in each subpopulation is ≤250 and continued decline can be inferred (see discussion under Clause 4.3 above); and as a Vulnerable Species under Clause 4.5 (Low total numbers of mature individuals of species; equivalent to IUCN Standards and Petitions Committee 2024, Criterion D) as the number of mature individuals is ≤1000 and Clause 4.7 (Very highly restricted geographic distribution of species– vulnerable species; equivalent to IUCN Standards and Petitions Committee 2024, Criterion D2) as the AOO is ≤ 20 km 2. This subspecies does not appear to be eligible to be listed under Clauses 4.2 (Reduction in population size of species; equivalent to IUCN Standards and Petitions Committee 2024, Criterion A) or Clause 4.6 (Quantitative analysis of extinction probability; equivalent to IUCN Standards and Petitions Committee 2024, Criterion E).

Additional specimens examined [location details redacted]

NEW SOUTH WALES. Central Tablelands:‘ Little Waco’, 1340 Ophir Rd , Rock Forest , 17 Dec.2015 G.P.Phillips 29 & A.E.Orme (NSW847720);1391 Ophir Rd , Rock Forest , North Jack site, 17 Dec. 2015, G.P.Phillips 28 & A.E.Orme (CANB n.v., NSW); North Jack site, ~ 1 km S along track from Ophir Road turn-off ~ 17 km WNW from Bathurst , 8 Apr. 2008, P.Carmen 377, C. Hook, R.Armstrong & K.Bollard, (NSW930639); ~ 12 km west of Bathurst , Oct. 2015, T.Bangel s.n. (NSW857221); Crackerjack Rock, W of Bathurst, 27 Oct. 1963, C. K.Ingram s.n., (NSW75929); Bathurst , 32 Pine Ridge Road, 5 May 2011, M.F.Mulvaney 1 ( NSW); 1.3 km direct NNE of the summit of Crackerjack Rock, ~ 17 km W of Bathurst via Ophir Road, 26 Sep. 1988, J.D.Briggs 2433 (CANB n.v., NSW); 1.3 km direct north-north-east of the summit of Crackerjack Rock,~ 17km west of Bathurst via Ophir Road, 26 Sep. 1988, J.D.Briggs 2433 (CANB n.v., NSW); ~ 1 km north-east of Crackerjack Rock, 11 Mar. 1994, R.L.Johnstone 44 ( NSW); Crackerjack Rock, W of Bathurst, 27 Oct. 1963, C. K.Ingram s.n. ( NSW); ‘The Rocks’ property W of Bathurst, 23 Nov. 2001, L.R.Cole s.n. (NSW608324); ‘ Lunch Site’ on North Jack property, Ophir Rd, Rock Forest , 11 Dec. 2019, G.P.Phillip 982 & D.Shelly s.n. ( NSW); North Jack property, Ophir Rd, Rock Forest , 12 Dec. 2019, G.P.Phillips 983 & D.Shelly ( NSW); Crackerjack North, near Crackerjack Rock, 15 km West of Bathurst, 1 Apr. 2022, D.Shelly s.n. (NSW1078495); Pine Ridge Road, 15 km west of Bathurst , 01 Apr. 2022, D.Shelly s.n. (NSW1078496); ‘Little Waco’, Ophir Rd, Rock Forest , 11 Dec. 2019, G.P.Phillips 981 & D.Shelly (CANB n.v., NSW1059946) .