Diuris arenaria (a terrestrial orchid) - endangered species listing

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list Diuris arenaria D.L. Jones, a terrestrial orchid, as an ENDANGERED SPECIES on Part 1 of Schedule 1 of the Threatened Species Conservation Act. Listing of endangered species is provided for by Part 2 of the Act.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Diuris arenaria was first described by D.L. Jones in 1999 and was previously known as Diuris sp. aff. punctata (Nelson Bay).

2. Diuris arenaria (Orchidaceae) has been described in Orchadian Volume 12(12) (1999) by Jones as: Tuberous terrestrial herb growing singly or in loose groups. Leaves basal, semi-erect to lax, conduplicate, usually 2, linear to linear-lanceolate, 15 - 50 cm long, 2 - 6 mm wide, green, base sheathing, apex acuminate. Scape 15 - 50 cm tall, slender, green, 1 - 9 flowered. Sterile bracts closely sheathing, usually 2, narrowly lanceolate, 20 - 70 mm long, 4 - 8 mm wide, acute to acuminate. Fertile bracts closely sheathing, narrowly lanceolate, 12 - 45 mm long, 3 - 5 mm wide, acute to acuminate. Pedicels 10 - 35 mm long, very slender, straight. Ovaries obovoid, 3 - 7 mm long, 2 - 4 mm wide. Flowers porrect, 20 - 30 mm diameter, mauve to light purple, labellum darker, callus area yellowish, lateral sepals purplish brown. Dorsal sepal porrect in the proximal third, then obliquely erect to erect, ovate to ovate - lanceolate, 10 - 18 mm long, 7 - 11 mm wide, apex broadly obtuse to nearly truncate. Lateral sepals obliquely deflexed, parallel or crossed, ensiform to narrowly lanceolate, 15 - 40 mm long, 1.6 - 3 mm wide; margins involute; apex asymmetrically acute to acuminate. Petals obliquely erect to recurved, lamina ovate, elliptic or obovate, 10 - 17 mm long, 6 - 10 mm wide, apex broadly obtuse, claw 3 - 6 mm long, blackish, widest near the apex, tapered to the base, curved. Labellum 10 - 14 mm long, obliquely decurved, 3 - lobed, lateral lobes narrowly oblong to oblong, 2.5 - 5 mm long, 1 - 2 mm wide, erect and closely flanking the column, outer margins entire to irregular, mid - lobe ovate - cuneate, 8 - 12 mm long, 7 - 11 mm wide, margins entire to shallowly crenate, apex obtuse to acute. Labellum callus consisting of 2 divergent purple ridges extending into the base of the mid - lobe, incurved apically, a yellow patch between them. Column porrect from the end of the ovary, 4.5 - 5 mm long, 2.5 - 3 mm wide. Column wings lanceolate, c. 5 mm long, c. 1.8 mm wide at the base, white with a prominent yellow, convolute basal flange, distal margins irregularly erose. Anther narrowly ovate, c. 4 mm long, c. 2 mm wide, purplish brown. Pollinarium c. 2.5 mm long, c. 1.5 mm wide; viscidium elliptic, c. 0.7 mm long; pollinia clavate, 2.2 mm long, white, mealy. Stigma elliptic, c. 3 mm long, c. 2.5 mm wide. Capsules obovoid, 15 - 20 mm long, 6 - 8 mm wide, ribbed.

3. The species occurs only on the Tomaree Peninsula near Newcastle in the North Coast botanical subdivision of New South Wales. It is currently known from three main locations, two of which are reserved but occur in areas subject to disturbance. Other scattered individuals are known to occur outside reserves.

4. The main threats to Diuris arenaria are continued clearing and loss of habitat. Loss of habitat and known populations has occurred in the past. Slashing regimes may adversely affect the species.

5. In view of 3 & 4 above the Scientific Committee is of the opinion that the species is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Proposed Gazettal date: 26/5/00
Exhibition period: 26/5/00 - 30/6/00