A Taxonomic Revision of Mezoneuron (Leguminosae: Caesalpinioideae: Caesalpinieae) Author Clark, Ruth P. text Phytotaxa 2016 2016-09-14 274 1 448 450 http://dx.doi.org/10.11646/phytotaxa.274.1.1 journal article 10.11646/phytotaxa.274.1.1 1179-3163 13657001 9. Mezoneuron enneaphyllum (Roxburgh) Wight & Arnott ex Bentham Pl. Jungh.: 258. 1852; Roxb. Hort. Bengal: 32. 1814 . nom. nud. Basionym. Caesalpinia enneaphylla Roxburgh, Fl. Ind. , ed. 2: 363. 1832. Holotype :— Roxburgh’s drawing n. 1425 , K!. Synonym. Mezoneuron glabrum Desf., Mém. Mus. Par. iv: 245. 1818. Holotype :—TIMOR, Leschenault s.n., P (P00293980!). Scandent shrub, 3–5 [–15] m in length. Stems with scattered recurved prickles 2–3 mm ; sparsely whitish tomentose when young, glabrous when older. Stipules triangular, flat, 1–3 × 1–3 mm , glabrous. Leaves with 5–14 pairs of pinnae; 7–10 [–12] pairs leaflets per pinna; petiole 3–6.5 cm ; leaf rhachis 6–32.5 [–40] cm, with recurved prickles in pairs at pinna insertion points, and sometimes scattered on the internodes; pinnae 4.1–7.5 cm , occasionally with recurved prickles paired at the leaflet insertion points, and scattered on the internodes; leaf rhachis and petiole glabrous to sparsely to moderately whitish to pale orange tomentose; pinna glabrous to sparsely to moderately whitish to pale orange tomentose. Leaflets opposite to subopposite; the terminal leaflets obovate, base oblique, apex rounded to emarginate, 10–23 × 5–9 mm ; lateral leaflets oblong, sometimes asymmetric, base oblique, apex rounded to retuse, 9–21 × 4–7 mm ; all leaflets with upper surface usually glabrous, occasionally very sparsely appressed pale hirsute, or with few hairs at base, lower surface usually glabrous, occasionally with sparse appressed pale hairs; 2˚ venation anastomosing, 3˚ venation reticulate, veins slightly raised, flat or sunken above, raised below. Inflorescence a raceme or panicle, terminal or axillary; occasionally with scattered recurved prickles on the peduncle; glabrous, or sparsely to moderately whitish to orange tomentose; pedicels 8–15 [–20] mm, articulated 1–3 mm below hypanthium, glabrous or very sparsely whitish to orange tomentose. Bracts sometimes present, persistent, triangular or semicircular with acuminate apex, 1–2 × 0.5–2 mm , subglabrous to sparsely tomentose; bracteoles lanceolate, acuminate, 1–2 mm , sparsely orange tomentose on both surfaces. Flower with a hypanthium ca. 1–2 × [4–] 6–8 mm ; lower calyx lobe [5–] 7–10 × 4–5 mm , other lobes [4–] 5–6 × 3–5 mm , hypanthium and calyx sparsely tomentose on outer surface, glabrescent, inner surface glabrous. Median petal reflexed backwards, inrolled, blade obovate, claw distinct, oblong; a pronounced transverse flap of tissue on the inner surface between the claw and the blade; blade 4–6 × 5–7 mm , claw 3–4 × 2–3 mm ; a few hairs along margins of claw, or the whole glabrous. Upper lateral petals blade ovate to elliptic, 7–9 × 4–7 mm , including claw 1 mm long, some hairs on inner surface of claw and base of petal, otherwise glabrous. Lower laterals blade ovate to A TAXONOMIC REVISION OF MEZONEURON Phytotaxa 274 (1) © 2016 Magnolia Press • 19 elliptic, 5–9 × 6–8 mm , including claw 1 mm long, a few hairs on inner surface of claw and base of blade, otherwise glabrous. Stamen filaments flattened, 8–10 (–13) mm long, the vexillary stamen glabrous or nearly so, remaining 9 stamens densely villous on the basal ⅓ or ½, on the inner surface; anther 1.5 mm long. Ovary 4–7 mm long, style 6–9 mm long, both glabrous, stigma funnel-shaped, ca. 1 mm wide, the rim papillate. Fruit coriaceous, elliptic, base cuneate, apex rounded or acute, the central nerve extending to form a beak, 8–12 × 2.4–4.2 cm , wing 4–10 mm wide; fruit surface glabrous; venation reticulate, raised and partially visible on fruit body, anastomosing and slightly visible on the wing; hypanthium persistent. Seeds 3–5 [–6] per fruit; positioned close to central vein, perpendicular to the vein, or angled towards apex of fruit, visible externally as linear ridges when mature; flat, ca. 7 × 5 × 2 mm , brown, smooth. Distribution :— China , Bangladesh , Myanmar , Vietnam , Thailand , Sri Lanka , Java, Lesser Sunda Islands. ( Fig. 10 ). FIGURE 10. Distribution of M. enneaphyllum in South East Asia. Habitat and ecology :—Wet forest, scrub. Elevation to 1450 m . Occurs in regions that experience a dry season. Phenology :—Flowering July–January, fruiting October–June. Preliminary conservation assessment :—Extent of Occurrence 6,034,965.788 km 2 = LC; Area of Occupancy 68.000 km 2 = EN. Category assigned :—Least Concern (LC).