Mezoneuron erythrocarpum (Pedley) R. Clark & E. Gagnon, 2016

Clark, Ruth P., 2016, A Taxonomic Revision of Mezoneuron (Leguminosae: Caesalpinioideae: Caesalpinieae), Phytotaxa 274 (1), pp. 448-450 : 448-450

19. Mezoneuron erythrocarpum (Pedley) R. Clark & E. Gagnon comb. nov.

Type:— AUSTRALIA, Queensland, Cook District, Rocky River , ca. 13 50 S, 143 25 E, 6 Sep. 1973, Hyland, B. 6812. Holotype BRI (BRI-AQ0016442, image!); isotypes K, (K000789364!, K000789365!), QRS.

Synonym. Caesalpinia erythrocarpa Pedley. Austrobaileya 5(1): 97–102. 1997.

Scandent shrub or liana, to 20 m in length. Stems unarmed or with scattered recurved prickles; glabrous to sparsely whitish to orange tomentose. Stipules persistent, triangular, ca. 1–2 × 1–2 mm, subglabrous to sparsely tomentose. Leaves (sub)opposite, with (3–) 4–7 pairs pinnae; 5–7 pairs leaflets per pinna; petiole 2–4.5 cm; leaf rhachis (4–) 7–16.5 cm, with recurved prickles in pairs at pinna insertion points, and sometimes scattered on the internodes; pinnae 3.5–8 cm; leaf rhachis, petiole, and pinna rhachis sparsely to moderately whitish pilose to appressed-pilose. Leaflets alternate, occasionally opposite or subopposite; the terminal leaflets slightly obovate, base oblique, apex rounded to retuse, 1.2–2.1 × 0.7–1.4; lateral leaflets elliptic, base oblique, apex rounded to retuse, 1.1–1.8 × 0.6–1.3; all leaflets with upper surface glabrous or with scattered appressed hairs, lower surface glabrous or with sparse appressed hairs; 2˚ venation anastomosing, 3˚ venation reticulate, 2˚ veins slightly visible above, 2˚ and 3˚ veins slightly visible below. Inflorescence a terminal panicle (occasionally a raceme), 13–40 cm (or more), the racemes opposite; axes subglabrous to moderately whitish to orange tomentose; pedicels 3–8 mm, articulated 0–1 mm below hypanthium; axes with few prickles on lower parts, sparsely to moderately orange tomentose, denser around articulation. Bracts persistent, triangular, ca. 1–2 × 1–2 mm, glabrous to sparsely tomentose; bracteoles caducous, lanceolate, the apex acute, 3–4 × 1 mm, sparsely tomentose. Flowers with a hypanthium 2–3 × 4–5 mm, outer surface moderately to densely orange tomentose; lower calyx lobe 6–7 × 3–4 mm, other lobes 5–6 × 2–3 mm, all (subglabrous to) sparsely to moderately orange tomentose, hair denser on lower lobe. Median petal obovate, 6–7 × 3–4 mm, with transverse flap of tissue on inner surface between claw and blade, the flap of tissue densely orange tomentose, petal otherwise glabrous. Upper lateral petals broadly elliptic, narrowed to claw at base, 5–6 × 4–5 mm, including claw 0.5–1 mm long, few hairs on inner surface of claw, petal otherwise glabrous. Lower laterals broadly elliptic, narrowed to claw at base, 5–6 × 3–4 mm, including claw 0.5–1 mm long, petal with few hairs on inner surface of claw, otherwise glabrous. Stamen filaments 6–7 mm long, moderately villous on the basal ½; anther ca. 1.5 mm long. Ovary ca. 3 mm long, densely appressed tomentose; style ca. 5 mm long, glabrous or with sparse hairs along entire length; stigma cupular or funnel-shaped, the rim papillate. Fruit chartaceous, elliptic, base cuneate, sometimes oblique, apex acute, sometimes with a slight beak, 3–5 × 2–2.7 cm, wing arising basally up to 5 mm along central vein, 4–5 mm wide; fruit surface with sparse, semi-appressed, whitish to pale orange hairs;

A TAXONOMIC REVISION OF MEZONEURON

Phytotaxa 274 (1) © 2016 Magnolia Press • 35 venation reticulate, raised and visible on the fruit body, no veins visible on the wing; hypanthium persistent. Seeds 1 per fruit, slightly visible in outline on fruit exterior when mature.

Distribution:—Endemic to Australia (Queensland) ( Fig. 22).

Habitat and ecology:—Riverine rainforest. Elevation 75–850 m.

Phenology:—Flowering and fruiting July–September.

Preliminary conservation assessment:—Extent of Occurrence 16,461.975 km 2 = VU; Area of Occupancy 92.000 km 2 = EN.

Category assigned:—Vulnerable (VU).

Taxonomic notes:— Mezoneuron erythrocarpum does not occur in New Guinea, as it has been previously reported to. The specimen Brass 7498 (BM, BRI) from New Guinea, cited by Pedley (1997) as Caesalpinia erythrocarpa , is Mezoneuron scortechinii . The specimen Schodde 2246, listed in the Australian Virtual Herbarium ( AVH 2015) as M. erythrocarpa , is also M. scortechinii .