Mezoneuron baudouinii, Guillaumin

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

22. M. baudouinii Guillaumin

Contribution à la Flore de la Nouvelle-Calédonie. Bulletin du Muséum National d’Histoire Naturelle 31: 482. 1925.

Lectotype:— NEW CALEDONIA: Nouméa, Pancher 176, P (P00379673!), Clark & Gagnon 2015; isolectotypes P (P00379675!, P00379674!).

Remaining syntype:— NEW CALEDONIA: Nouméa , Baudouin 249, P (P00751918!) .

Scrambling shrub, becoming lianescent, to ca. 5 m in length. Stems with scattered small recurved prickles, older stems with corky spine-tipped tubercles; sparsely to moderately whitish to ferruginous tomentose. Stipules semi-persistent, triangular, 0.5–2 × 0.5–2 mm, glabrous to densely tomentose. Leaves with (4–) 5–11 pairs pinnae; (3–) 5–15 pairs leaflets per pinna; petioles 2–7.5 cm; leaf rhachis (6–) 9–25 cm long, unarmed (especially older leaves), or with small recurved prickles in pairs at the pinna insertion points, and sometimes scattered on the internodes;

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CLARK pinnae (2–) 3–7.5 (–9) cm long; leaf rhachis, petiole and pinna rhachis glabrous or sparsely to moderately tomentose with whitish to ferruginous hairs. Leaflets opposite, sometimes subopposite on lower parts of pinna; oblong, strongly oblique at base, apex rounded to retuse; the terminal leaflets 0.7–2.2 × 0.4–1.2 (–1.7) cm; lateral leaflets 1–2.3 × 0.4–1.5 cm; all leaflets glabrous on both surfaces, or sometimes with few ferruginous hairs on lower portion of the midvein, on upper or lower surface; midvein usually excentric, slightly diagonal, sunken above, slightly raised below, 2˚ veins anastomosing, 3˚ veins reticulate, veins faintly to clearly visible. Inflorescence a panicle, usually few-branched, axillary or terminal, 9–20 cm long, glabrous, or very sparsely, occasionally densely, white to ferruginous tomentose on the axes, hairs sometimes only at pedicel insertion points; pedicels 2–8 mm, articulated 1–2 mm below calyx. Bracts sometimes present, persistent, triangular, 1–2 × 0.5 mm, moderately to densely orange tomentose; bracteoles caducous, lanceolate to elliptic, apex acute, inrolled, 1–1.5 × 0.5–1 mm, sparsely to moderately ferruginous tomentose. Flowers with a hypanthium ca. 1 mm deep, usually glabrous, occasionally moderately ferruginous tomentose; lower calyx lobe ca. 5 × 3 mm, other lobes ca. 4 × 2 mm, all glabrous. Median petal (3–) 4–6 × 2–2.5 mm, with a circular patch of dense, dark ferruginous hairs on inner surface between claw and blade, and hairs on margins of claw, outer surface glabrous. Upper lateral petals elliptic to slightly obovate, 4–5 × 2–2.5 mm, blade glabrous, claw very sparsely ferruginous tomentose on inner surface. Lower lateral petals elliptic to slightly obovate, 4–5 × 2–3 mm; blade glabrous, claw very sparsely ferruginous tomentose on inner surface. Stamen filaments 3–6 mm long, densely ferruginous tomentose on the basal ½; anthers ca. 0.5–0.75 mm long. Ovary 1–1.5 mm long, densely ferruginous pubescent, style 2–3 mm long, glabrous, or ferruginous pubescent on the basal ½ of length or less; stigma funnel-shaped, the rim papillate. Fruit elliptic, the base cuneate, apex acute or the wing extending to form a short beak; (3.4–) 4.2–6.4 × 2–3.5 cm, wing 3–5 mm wide, extending along upper ⅔ to entire length of fruit; fruit surface glabrescent, sometimes with a few hairs at the base and on the margins; venation reticulate, raised and visible on the fruit body, no veins visible on the wing; hypanthium persistent. Seeds 1 per fruit; suborbicular, generally visible in outline on fruit exterior when mature, flat 1–1.1 cm diameter, brown, smooth.

Distribution:—Endemic to New Caledonia. Ile Art; Grand Terre, North and South Provinces, West side of island. ( Fig. 25).

Habitat and ecology:—Occurs in wet forest, or maquis, on ultramaphic soil. Elevation 0–400 m.

Phenology:—Flowering December–July, fruiting June–August.

Preliminary conservation assessment:—Extent of Occurrence 11,469.543 km ² = VU; Area of Occupancy 36.000 km ² = EN.

Category assigned:—Data Deficient (DD). This species has been only occasionally observed. From its known distribution, this species might be more common than the actual herbarium data reveal. Therefore, M. baudouinii is

A TAXONOMIC REVISION OF MEZONEURON

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assigned as Data Deficient and should be re-assessed when more observations have been made that will clarify its distribution (RLA Flore NC 2016).