Solanum bauerianum - species presumed extinct listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the shrub Solanum bauerianum Endl., Bridal Flower as a SPECIES PRESUMED EXTINCT in Part 4 of Schedule 1 of the Act. Listing of Species Presumed Extinct is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Solanum bauerianum Endl. (family Solanaceae) is described as a 'shrub or small tree to c. 3 m tall, glabrous; wood soft. Leaves alternate or sometimes paired, unequal; lamina lanceolate-elliptic, 6-13 cm long, 2.5-6 cm broad, acute at base, attenuate onto petiole, entire or irregularly and coarsely dentate-undulate, acute to acuminate at apex, blunt tipped. Inflorescence terminal or axillary, densely cymose-paniculate, many flowered; peduncle 1.5-3.5 cm long; pedicel 5-10 mm long, +deflexed in fruit. Calyx 1.5-2 mm long; lobes short and broad, apiculate. Corolla rotate-stellate, 1.5-1.7 cm diam., white; lobes broadly ovate-triangular, apiculate. Anthers 2 mm long. Berry globose, c.6 mm diam., bright red or scarlet. Seeds c. 3 mm long.' (Green 1994).

2. Solanum bauerianum is now extinct globally. It was only known from the Lord Howe Island and the Oceanic Norfolk Island group (Rabbit and Norfolk Islands). In NSW, the species was restricted to Lord Howe Island (Green 1994), where the last wild collection was made in 1937 (Pickard 1983), although a 1949 collection from cultivation is known (Green 1994).

3. Searches of Lord Howe Island have been unsuccessful in locating Solanum bauerianum. Pickard (1983) undertook intensive searches in the period of 1970-1980, but failed to find any plants. Hutton (2005) failed to find the species after targeted searching at known collection locations, taken from records at the National Herbarium of NSW. He also searched areas where trees had previously been seen including Little Mutton Bird Ground, North Bay, Steven's Reserve, and in the rectory garden, but could not locate any plants.

4. The habitat of the plant can be inferred from where specimens have previously been collected. This includes valley floors with lowland Drypetes/Cryptocarya (Greybark/Blackbutt) rainforest through to more stunted vegetation towards the ridge tops also containing Celtis conferta spp. amblyphylla (Cottonwood), Olea paniculata (Maulwood), Lagunaria patersonia (Sallywood), Ochrosia elliptica (Berrywood), and mixes with smaller shrubs such as Dodonaea viscosa (Hopwood), Rapanea platystigma, Cassinia tenuifolia (Bully bush) and Myoporum insulare (Juniper).

5. The causes of decline and extinction of Solanum bauerianum are unknown, however there are a number of factors that may have contributed to the demise of the species. Areas of suitable habitat for Solanum bauerianum have been cleared and fragmented to make way for settlements and grazing land. 'Clearing of native vegetation' is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995. Cattle, goats and pigs may have affected the species in the past through grazing and disturbance of habitat. 'Predation, habitat degradation, competition and disease transmission by Feral Pigs, Sus scrofa Linnaeus 1758' and 'Competition and habitat degradation by Feral Goats, Capra hircus Linnaeus 1758' are listed as Key Threatening Processes under the Threatened Species Conservation Act 1995. Rats were introduced to Lord Howe Island in 1918 and are thought to have eaten the fruits and seeds of Solanum bauerianum (Auld & Hutton 2004). 'Predation by the Ship Rat Rattus rattus on Lord Howe Island' is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995. Numerous weeds occur in disturbed habitats throughout the island. Pickard (1984) has documented the increase in invasion of weeds on the island up to 1981.

6. Solanum bauerianum Endl. is eligible to be listed as a Species Presumed Extinct at a particular time as, in the opinion of the Scientific Committee it has not been recorded in its known or expected habitat in New South Wales, despite targeted surveys, over a time frame appropriate, in the opinion of the Scientific Committee, to its life cycle and form.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 13/08/10
Exhibition period: 13/08/10 - 08/10/10

References:

Auld TD, Hutton I (2004) Conservation issues for the vascular flora of the Lord Howe Island. Cunninghamia 8, 490-500.

Green PS (1994) 'Flora of Australia Vol. 49 Oceanic Islands 1'. (Australian Government Printing Service: Canberra), pp. 293-305.

Hutton I (2005) 'Rare plants survey 2 - Lord Howe Island'. Report to Department of Environment and Conservation NSW.

Pickard J (1983) Rare or threatened vascular plants of Lord Howe Island. Biological Conservation 27, 125-139.

Pickard J (1984) Exotic plants on Lord Howe Island: distribution in space and time, 1853-1981. Journal of Biogeography 11, 181-208.