Mezoneuron schlechteri, 2015

Clark, Ruth P. & Gagnon, Edeline, 2015, A revision of Mezoneuron (Leguminosae: Caesalpinioideae) in New Caledonia, with perspectives on vegetation, geology, and conservation, Phytotaxa 207 (1), pp. 68-92 : 82-84

M. schlechteri (Harms) R. Clark comb. nov.

Basionym. Caesalpinia schlechteri Harms

Harms, H.A.T. (1906) Beiträge zur Kenntnis der Flora von Neu-Kaledonien. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie: 1–274

Type:— NEW CALEDONIA: Auf den Bergen bei Oubatche, 800m, 26 Dec. 1902, Schlechter, F.R.R. 15572 (fl.)

Lectotype:—(here designated) M (M0217766, image!); isolectotypes:—BR, (000005110605, image!), K (K000556378!), L (L0018794!)

Liana to 20 m or more. Stems unarmed, or with scattered recurved prickles, glabrous or sparsely to densely ferruginous tomentose. Stipules semi-caducous, triangular, 0.5–1 × 0.5–1 mm, subglabrous to sparsely tomentose. Leaves bipinnate, rhachis unarmed, or with recurved prickles up to 5 mm in length, in pairs at pinna insertion points and scattered on the internodes, sparsely to moderately ferruginous tomentose; pinnae (2–) 3–7 (–8) opposite pairs; paripinnate; leaflets opposite, (3–) 4–8 (–14) pairs per pinna; petiole 2–5.5 (–8) cm; rhachis (3–) 5–23 cm; pinnae 2.8–12.7 cm, sparsely to moderately ferruginous tomentose, occasionally with scattered recurved prickles on the rhachis. Leaflets elliptic to rhomboid, strongly oblique at base, apex obtuse to slightly emarginate; terminal leaflets 2–4.7 × 0.6–3.1 cm; median laterals 1.8–4.4 × 0.6–2.3 cm; secondary veins reticulate, anastomosing, clearly visible on both surfaces, or indistinct on upper surface; upper surface usually glossy, glabrous, or sometimes with a few hairs at the base or along the basal part of the margins; lower surface glabrous, with sometimes a few hairs at the base or along the basal part of the margins. Inflorescence a raceme or panicle, axillary, supra-axillary or terminal, 13–31 cm long, glabrous, or sparsely to moderately ferruginous tomentose on all parts, occasionally a few recurved prickles on the lower axis. Pedicels 3–10 mm, not articulated, glabrous to densely ferruginous tomentose. Bracts sometimes singly at base of racemes, triangular, 0.5–2 × 0.5–1 mm, subglabrous to sparsely tomentose; bracteoles at base of pedicel, usually caducous, 1–1.5 × 0.5–1 mm, lanceolate, inrolled, sparsely to moderately orange pubescent, or ciliate only along margin, sometimes glabrescent. Hypanthium 1–2 mm deep, glabrous, lower calyx lobe c. 8 × 3–4 mm, other lobes c. 6 × 3–4 mm, all lobes glabrous or with ciliate margins. Median petal 4–6 × 1.5–3 mm, with a circular patch of dense, dark ferruginous hairs on inner surface where claw and blade meet, and on margins of claw, outer surface glabrous; upper lateral petals (4–) 5–8 × 1.5–3 mm; lower laterals (4–) 5–8 × 1.5–4 mm; all laterals with blade glabrous, claw very sparsely ferruginous tomentose on inner surface. Stamens 10, filaments 5–11 mm long, lower ⅓ to ½ with long translucent or ferruginous tomentose hairs. Ovary 3–4 mm long, glabrous, style 5–7 mm, sparsely to moderately pale translucent or ferruginous tomentose on lower half, sometimes thickened towards apex; stigma funnel-shaped, the rim fimbriate. Fruit glabrous, 4–5.6 × 1.7–2.6 cm, wing 4–6 mm wide. Seeds 1 per fruit. ( Figure 2 , Figure 9 )

Distribution:— Endemic to New Caledonia. Grande Terre, North and South Province, East to West (primarily

East). ( Figure 10 )

Habitat and Ecology:— Dense wet forest (Appendix 2), on ultramaphic and non-ultramaphic (volcanosedimentary) soil. Elevation 100– 800 m.

Phenology:— Flowering July to January, fruiting December to February

Preliminary Conservation Assessment:— Extent of Occurrence 10,382.55 km 2 = VU, Area of Occupancy 84.00 km 2 = EN

Category assigned:— Vulnerable

Rationale:— M. schlechteri occurs in wet forest. It can be considered as Vulnerable as it is found in a number of localities throughout the island, and its habitat, although subject to the threats discussed in the introductory text (primarily logging), is not thought to be in immediate danger of widespread destruction throughout the island.

Nomenclatural Notes:— The author of the name, H. Harms, was based in Berlin herbarium (B), and no duplicate of the type is available from this institution (if one existed, it is likely that it was destroyed). The specimen at M is designated here as the lectotype, as this herbarium is in the country in which the author was based, and it is therefore more likely to have been seen by him. It is also taxonomically informative, bearing flowers and leaves.

Figures

FIGURE 2. Illustration of M. montrouzieri, with leaf detail of all species. (a) M. montrouzieri habit, leaf and inflorescence, with detail showing idioblasts on leaf undersurface; flower, side view; flower opened out; petals, inner surface (median, 2 upper laterals, 2 lower laterals); ovary and style; fruit with detail of hairs—drawn from Clark, R.P. 160; (a)(i) M. montrouzieri glabrous ovary; (a)(ii) leaf pinna—drawn from Clark, R.P. 150 (specimen formerly identified as M. deverdiana); (b) pinna of M. baudouinii—drawn from Clark, R.P. 141; (c), (c)(i) pinnae of M. schlechteri (showing variation)–drawn from Clark, R.P., 132, 134; (d) pinna of M. rubiginosum—drawn from McPherson, G. 2089; (e) pinna of M. ouenensis—drawn from Balansa, B. 312. Illustration by Margaret Tebbs.

FIGURE 9. M. schlechteri: 9a. flower; 9b. inflorescence (Clark, R.P. 132)

FIGURE 10. Distribution of M. schlechteri