Adelopetalum continentale D.L.Jones, M.A.Clem. & H.Zimmer, 2024

Jones, David L., Zimmer, Heidi C., Clements, Marka., Bruhl, Jeremy J., Christian, Joel, Copeland, Lachlan M., Hutton, Ian, Andersen, Alexandra & Wilson, Melinda, 2024, Characterisation of Adelopetalum argyropus (Orchidaceae; Malaxideae) with the description of two related new species and two new combinations, Phytotaxa 678 (1), pp. 83-95 : 88-90

Adelopetalum continentale D.L.Jones, M.A.Clem. & H.Zimmer , sp. nov. ( Fig. 4 )

TYPE: — AUSTRALIA . New South Wales: Cottan-Bimbang National Park [precise location withheld], 9 Apr 2023, Bruhl 3799 & Quinn (holotype: CANB 959724 ; isotypes: NE 114414 , NSW) .

Bulbophyllum tuberculatum sensu Clemesha (1979) , not Bulbophyllum tuberculatum Colenso (1884: 336) .

The new species is similar to Adelopetalum argyropus but differs by its ovoid to conical or transversely elliptic pseudobulbs with a flat apex (globose to obconical or turbinate pseudobulbs in A. argyropus , the apex with shallow to deep depressions), flowers opening widely (not in A. argyropus ); lateral sepals widely divergent, cream to pale yellow with a contrasting protruding yellow to pale orange labellum (weakly divergent in A. argyropus , not longer than sepals, cream to greenish white); also to A. howense but differs by its porrect to weakly decurved flowers (versus pendent flowers), shorter, narrower lateral sepals tapered to a drawn-out subacute apex (3.5–4.0 × 2.0 mm at widest point versus 4.5 × 2.3 mm in A. howense with an obtuse apex) and slightly narrower, yellow to pale orange labellum (versus dark orange).

Large, compact herbs with crowded growths. Roots 1 mm across, white, spreading, unbranched. Emerging shoots covered with white, felted, fugacious bracts. Pseudobulbs ovoid to conical or transversely elliptic, 5–8 × 3–6 mm, green, surface irregularly verrucose, weakly furrowed or ribbed, apex truncate, flat, scurfy from remnants of fugacious bracts. Leaf single; petiole 1–2 mm long; lamina oblong to elliptical, 20–25 × 3–6 mm, dark green, rigid, midrib sunken, strongly ridged abaxially, margins recurved, apex subacute to apiculate. Racemes arising from base of a pseudobulb, wiry, 15–35 mm long, straight or irregularly curved, green to brownish; sterile bract basal on peduncle, narrowly ovate-lanceolate, 4 × 2 mm, whitish green, apex obtuse; peduncle much longer than rachis, 0.5 mm wide, both parts bearing numerous translucent/whitish silica-like warts. Pedicels 0.5–1.0 mm long, strongly curved, smooth or sparsely verrucose. Ovaries asymmetrically obovoid, 1.5–2.0 × 0.5 mm, green to brownish, ribs verrucose. Floral bracts 1.5 mm long, acute. Flowers 1–4, porrect to weakly decurved, opening widely, 3.0–3.5 × 4.5–5.5 mm, sepals and petals cream to pale yellow, basal 1/3 of labellum pale yellow, distal 2/3 of labellum pale yellow/ orange. Sepals spreading widely, petals remaining near dorsal sepal, labellum protruding prominently. Dorsal sepal porrect to incurved, narrowly ovate-lanceolate to narrowly cuneate when flattened. 3.5–4.0 × 1.3 mm, margins flat, entire, apex subobtuse. Lateral sepals free, widely divergent, 3.5–4.0 × 2.0 mm, at widest point near base, shallowly falcate, asymmetrically ovate-lanceolate when flattened with an expanded basal flange on the anterior margin forming a shallow pouch, midvein thickened, yellowish, exterior surface with irregularly scattered siliceous bumps, tapered to a drawn-out subacute apex. Petals incurved close to the column, partially enclosed by the dorsal sepal, elliptic-oblong to oblong in outline, margins pinched inwards or tapered in proximal 1/3, 2.0–2.3 × 0.8 mm, distal margins irregularly papillate, apex obtuse to subobtuse. Labellum claw attached to labellum base and apex of column foot, ligulate, 0.3 × 0.2 mm. Labellum lamina trilobed, narrowly elliptical to lingulate, tapered evenly from near midpoint to the apex, 3.0 mm long when flattened, yellow to pale orange and erect in the proximal third, distal two-thirds recurved more or less at right angles, dark yellow to orange; labellum at midpoint of lateral lobes 2.0 mm wide when flattened; lateral lobes erect, curved, 1.0 × 0.7 mm, outer margin broadly rounded; midlobe linguiform, 1.8 × 1.0 mm wide at base, 0.4 mm high (thick), convex, underside hollow, distal third recurved, tapered to an obtuse to subobtuse apex. Callus 1.0 × 0.7 mm wide, an obscure, oblong, plate-like area between the lateral lobes adorned with two shallow ridges. Column 1.2 × 0.7 mm, white, with broad, incurved wings 0.7 mm wide. Column foot tapered, 1.2 × 0.3 mm, distally incurved. Anther ovate, 0.25 × 0.20 mm wide, erostrate. Stigma 0.3 × 0.2 mm, sunken. Pollinarium not seen. Capsules asymmetrically ovoid, 5.0 × 3.5 mm, ribs prominent, with reddish warts, on curved, reddish pedicels.

Etymology:—Referring to its distribution on mainland Australia as distinct from related species occurring on oceanic islands.

Flowering:—March–April, August–December.

Distribution:—Endemic to south-eastern Queensland (McPherson Ranges in the far south-east) and north-eastern New South Wales (Border Ranges, Comboyne Plateau, Coopernook Creek east of Dorrigo, Enfield State Forest, Cottan-Bimbang National Park south-east of Walcha and Gibraltar Range); ca. - 1,200 m elev.

Habitat;—Epiphytic on trees (branches, high in the canopy), mostly in wetter forests, including rainforest and humid open forests, on Exocarpos cupressiformis Labillardière (1800: 155) (Cherry Ballart), Elaeocarpus kirtonii F.Mueller ex F.M.Bailey in Bailey (1886: 8) (White Quandong), Pittosporum undulatum Ventenat (1802 : t.76) (sweet pittosporum), Didymocheton mollis (as Dysoxylum mollissimum subsp. molle ( Miquel 1868: 18) Mabberley in Mabberley (1994: 309)) ( Clemesha 1979), Diospyros pentamera (Woolls & Mueller in Mueller 1864: 82) Mueller in Mueller (1867: 35) (native ebony) (Walsh 19f93), Leptospermum brevipes Mueller (1855: 45) (slender teatree) and Banksia monticola subsp. integrifolia K.R.Thiele in Thiele & Ladiges (1994: 406) (white mountain banksia). Populations in Lamington National Park, south-eastern Queensland, grow on the upper branches of tall trees in highland rainforest, where most plants have been found on fallen branches.

Herbarium records and online records of human observations (supported by images) of Adelopetalum continentale are scarce (<20 records).

Conservation status:—Although having a broad extent of occurrence (estimated 28,000 km 2), populations of this species are disjunct, resulting in an estimated area of occupancy of 48 km 2. The area of occupancy meets the geographic range threshold for listing as endangered. Moreover, several populations (Cottan-Bimbang National Park and adjacent Enfield State Forest, and Gibraltar Range National Park) were severely impacted by bushfires in 2019–2020, with declines in populations of>50%.

Illustrations:— Jones (1988, p. 504), as Bulbophyllum argyropus ; Jones (2006, p. 420, Jones 2021, p. 696) as Adelopetalum argyropum ; Copeland & Backhouse (2022, p. 19), as Bulbophyllum argyropus .

Additional specimens examined:— AUSTRALIA . New South Wales: ex Wauchope, 7 Jun 1982, Clements. s.n. (CBG 8302249); ex Wild Cattle Creek State Forest, 1 Mar 1984, Taylor 2374 (CBG 8404132); ex Briggsvale, Dorrigo, 1 Mar 1995; Leilkajis DLJ13856 (CANB 678644); w of Wauchope, 21 Jul 2009, Sinclair ORG5613 (CANB 892477). Queensland: ex McPherson Range, 17 Mar 1995, Leilkajis DLJ13872 (CANB 678650); Lamington NP, 17 Sep 1992, Charlesworth ORG829 (CANB 650635); Lamington National Park, 3 May 2006, leg. ign. ORG 5190 (CANB 737244).

Figures

FIGURE 4. Adelopetalum continentale.A, B. Habit. C, D. Flower. Photos by J. J. Bruhl.