Mezoneuron andamanicum Prain J. Asiat. Soc. Bengal

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

4. Mezoneuron andamanicum Prain J. Asiat. Soc. Bengal ii, 61: 131. 1892.

Type:— INDIA: South Andaman, near Port Blair at Protheropur, Rangachang, Prain s.n.

Lectotype (here designated):—CAL (CAL0000011174, image!); isolectotypes CAL (CAL0000011172, image!), K (K000264172!, K000264173!)

Synonym. Caesalpinia andamanica (Prain) Hattink. Reinwardtia 9(1): 15. 1974.

Synonym. Mezoneuron kunstleri Prain. J. As. Soc. Beng. ii 66(1): 233. 1897. ( Prain 1897a)

Type:—MALAYA, Perak, Sunga Ryah , Oct. 1880, Kunstler (King’s collector) 895. Holotype CAL; isotype K (K000789322!).

Woody climber or scandent shrub, spreading to 20 m in length. Stems with scattered recurved prickles to 5 mm; glabrous. Stipules caducous, triangular, ca. 1.5–2 mm × up to 2 mm broad at base, apex acute. Leaves with (3–) 4–11 pairs pinnae; 8–12 leaflets per pinna; petiole 3–11.5 cm; leaf rhachis 4.7–28 [–50] cm, with recurved prickles in pairs at pinna insertion points, and scattered on the internodes; pinnae (4–) 7–15 cm, pinna rhachis with recurved prickles paired at leaflet insertion points, and sometimes scattered on the internodes, with a single prickle at the apex, ca. 1–2 mm; leaf rhachis, petiole, and pinna rhachis glabrous. Leaflets alternate (sometimes subopposite towards apex of pinna), with a subopposite apical pair; the terminal leaflets elliptic, oblong, obovate, or ovate, base oblique, apex rounded to retuse, 2.5–5.0 × 1.5–2.9 cm; lateral leaflets elliptic, oblong, or obovate, base oblique, apex rounded, emarginate, 2.5–4.8 × 1.4–2.9 cm; all leaves glabrous on both surfaces; 2˚ venation anastomosing, 3˚ venation reticulate, faintly visible on both surfaces, midvein flat or sunken above, raised below. Inflorescence a panicle, axillary or terminal, to 60 cm [– 75cm]; a few recurved prickles sometimes present on lower parts of peduncle; mostly glabrous, or with some hairs on pedicels; pedicels 10–20 mm, articulated 1–2 mm below the hypanthium in flower, 3–4 mm in fruit, very sparsely white or orange tomentose, hairs denser where pedicels are inserted on inflorescence, and at pedicel articulation. Bracts sometimes present, persistent, triangular, ca. 1–2 × 1–2 mm, subglabrous; bracteoles caducous, not seen. Flowers with a hypanthium ca. 2–3 × 4–6 mm, glabrous or sparsely white or orange tomentose; lower calyx lobe 7–12 × ca. 8 mm, other lobes ca. 3–6 × ca. 5 mm, all lobes glabrous. Median petal obovate, inrolled, slightly reflexed backwards, a pronounced transverse flap of tissue on inner surface between claw and blade; blade 3–4 × 5–7 mm, claw 3–4 × 3–4 cm; margin of flap of tissue covered with with dense, villous, orange hairs, petal otherwise glabrous. Upper lateral petals ovate, blade 4–10 × 4 mm, claw 1 mm; glabrous apart from a few hairs on the inner surface of the claw. Lower lateral petals slightly obovate, 5–10 × 4–5 mm, including claw 1 mm long; glabrous apart from a few hairs on the inner surface of the claw. Stamen filaments slightly flattened, 6–15 mm long; with dense, villous orange hairs on the inner surface, on the basal ½; anther 2–3 mm long. Ovary 4–7 mm long, style 4–8 mm long, both glabrous, stigma funnel-shaped, to 2 mm wide, the rim papillate. Fruit coriaceous; elliptic, base cuneate, oblique, apex obtuse, the central nerve extending to form a beak; 9–15 × 2.8–4.7 cm, wing 7–13 mm wide; fruit surface glabrous; venation reticulate, raised and clearly visible on fruit body, anastomosing and slightly visible on the wing; the persistent hypanthium reflexed. Seeds 3–4 per fruit; oval to circular, visible in outline on fruit exterior when mature, perpendicular to the wing or angled slightly towards the apex of the fruit.

Distribution:— Myanmar, India, Malaya, Thailand, Laos, Vietnam, Sumatra. ( Fig. 5).

Habitat and ecology:—Forest; disturbed scrub; coastal; sandy beaches; river banks; chalk rocks; limestone. Elevation usually low, but to 500m.

Phenology:— Myanmar: Flowering October; Thailand, Laos, Vietnam: Flowering October–December, fruiting December–May; Malesia: Flowering May, October, fruiting October–March ( Larsen & Larsen 1980).

Preliminary conservation assessment:—Extent of Occurrence 2,306,205.590 km 2 = LC; Area of Occupancy 88.000 km 2 = EN.

Category assigned:—Least Concern (LC).

12 • Phytotaxa 274 (1) © 2016 Magnolia Press

CLARK