Mezoneuron montrouzieri, Guillaumin

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 : 75-79

M. montrouzieri Guillaumin in Guillaumin & Beauvisage, Species Montrouzieranae. Annales de la Société Botanique de Lyon 38: 87–88. 1913. Lectotype (here designated):— NEW CALEDONIA: Taulé, Deplanche 338, P (P00379688!); isolectotypes:—K! L (L0651493!), NY! P

(P00625915!) Remaining syntypes:— NEW CALEDONIA: Taulé, Deplanche 340 K (K000264184!), L (L0651493!), NY!, P (P00379688!, P00625915!,

P 02142824!); Taulé, Vieillard 2521, P (P00379687!, P 02142820!, P 02142822! P 02142823!); Ile Art (49 in herb. Lugd.) Mueller: 3,

12; Deplanche 558 P! (barcode unknown) Synonym.— M. deverdiana Guillaumin , Bulletin de la Société Botanique de France 83: 310. 1936. Syntypes:— NEW CALEDONIA: Cap Deverd, Vieillard 2533 (specimen not seen, the number as written in the protologue is possibly a typographic error, as the specimen Vieillard 2523! is determined as M. deverdiana ); Cap Deverd, Deplanche 341 K (K000556379!)

NY!, P (P00379664!, P00379665!, P00379689!, P00379690!); Cap Deverd, Pancher 41 (location of specimen unknown). Synonym. M. deverdiana Guillaumin var. glabrifoliolula Guillaumin (1936: 310) . Syntypes:— NEW CALEDONIA: Route de Canala , Balansa, B. 2447 L (L0651586!), P (P00379662!, P00379663!, P00624907!) ; prés l’embouchure du Dothio, Balansa, B. 3668 P (P00379661!, P00379686!); Taulé, Vieillard 2522 P! (barcode unknown).

Scrambling shrub to c. 6m. Stems unarmed, or with scattered recurved prickles, glabrous to very sparsely to moderately whitish to ferruginous tomentose. Stipules semi-caducous, triangular, c. 1–2 × 0.5 mm, moderately tomentose, or on margins only. Leaves bipinnate, rhachis unarmed or with recurved prickles in pairs at pinna insertion points, and scattered on the internodes (particularly on younger leaves); pinnae 1–6 opposite pairs, paripinnate; leaflets opposite to subopposite, 1–6 pairs per pinna; petioles 1.8–8.5 cm; rhachis (1.5–) 5.4–25 (–28.8) cm; pinnae (0.8–) 2.4–7 cm. Leaflet shape variable, with irregular margin, elliptic to orbicular, base oblique, apex obtuse or rounded to slightly emarginate, margin inrolled; terminal leaflets (1.2–) 1.5–3.6 (–4.3) × 0.8–2.5 (–3.3) cm; median laterals (1.1–) 1.6–3.4 × 0.8–2.6 cm; secondary veins reticulate, anastomosing, slightly impressed above and raised below; both surfaces glabrous to sparsely, occasionally moderately, tomentose, with somewhat appressed, whitish to ferruginous hairs. Inflorescence a panicle, often few-branched, axillary or terminal, flowers spaced up to 6 mm apart, 8–30 cm long, glabrous or sparsely to densely ferruginous tomentose. Pedicels 2–7 mm, articulated c. 1–2 mm below calyx, sparsely to moderately (densely when very young) ferruginous tomentose. Bracts sometimes singly at base of racemes, triangular, c. 0.5–1 × 0.5 mm, partially tomentose; bracteoles at base of pedicels, 1.5–4 × 0.5–1 mm, linear or lanceolate, acute, sparsely to densely ferruginous tomentose. Hypanthium c. 1 mm deep, glabrous or sparsely to moderately ferruginous tomentose, or hairs on margins only; lower calyx lobe 4–6 × 2–3 mm; other lobes 3–6 × 2–3 mm, glabrous or sparsely to moderately ferruginous tomentose. Median petal 3–6 × 1.5–3 mm, with a patch of translucent or ferruginous hair on inner surface where blade and claw meet, and hairs on margins of claw, outer surface glabrous; upper lateral petals 3–6 × 1.5–2 mm; lower laterals 3–6 × 1.5–2 mm; all laterals with blade glabrous, claw very sparsely ferruginous tomentose on inner surface. Stamens 10, (2–) 3–6 mm, filaments flattened, sparsely to densely tomentose, with long, translucent or whitish to ferruginous hairs on the lower half of the inner face or both faces. Ovary 2–3 mm long, glabrous, or densely pubescent with translucent, whitish, or ferruginous hairs, style 3–5 mm, very sparsely pubescent on lower half; stigma funnel shaped, the rim fimbriate. Fruit 2.4–5.4 × 1.4–2.4 cm, wing 2–4 mm, fruit surface glabrous or subglabrous, or sparsely to moderately ferruginous tomentose, glossy. Seeds 1 per fruit. ( Figure 2 , Figure 6 )

Distribution:— Endemic to New Caledonia. Distributed mostly on the West coast in the northern half of the island, with two localities on the East coast, in the southern part of the island. Ile Art; Grand Terre, North and South Provinces (primarily North), East to West (primarily West). ( Figure 5 )

Habitat and Ecology:— Maquis and sclerophyllous forest (Appendix 2), on ultramaphic or non ultramaphic soil.

Elevation 1– 900 m. Phenology:— Flowering December to August, fruiting November to July. Preliminary Conservation Assessment:— Extent of Occurrence 15,220.484 km 2 = VU, Area of Occupancy

60.00 km 2 = EN

Category assigned:— Endangered

Rationale:— M. montrouzieri occurs in maquis on ultramaphic or non ultramaphic soil, and in sclerophyllous forest (non ultramaphic soil). ( Table 2)

Several of the herbarium specimen records are located in areas that are now savanna or secondary thicket. According to the maps of Jaffré et al. (1998), at least some of these are in areas that were formerly vegetated with sclerophyllous forest. Precise information regarding the pattern of forest loss over time is not available, so we are unable to confirm that the specimens were collected in this habitat. However, some of the specimen label data do indicate that the vegetation was indeed sclerophyllous forest at the time of collection ( Table 2). For example, specimen Veillon 7298, according to the label, was collected in ‘fourre sclerophylle secondaire, substrat calcaire’, Cap Goulvain, Bourail, in 1990. The map of Jaffré et al. (1998) indicates that this area was formerly an area of sclerophyllous forest, whereas the map here provided (adapted from Jaffré et al. 2012), shows the current vegetation of this area to be savanna or secondary thicket.

In other cases, such as specimen Labat 3500, the label records dry forest, ‘forêt sèche basse’ in 2004, and this is supported by current vegetation data. It can be concluded with reasonable confidence, therefore, that sclerophyllous forest is one of the vegetation types in which M. montrouzieri occurs.

Mezoneuron montrouzieri can be considered as Endangered under IUCN criteria, as although it is fairly widely distributed over the islands, represented by a moderate number of populations, and found in two vegetation types, maquis and sclerophyllous forest, on both ultramaphic and non ultramaphic soil, these habitat types are the two most threatened in New Caledonia ( Jaffré et al. 1998). Both habitats are subject to damage through clearing, mining activities, and fires, and sclerophyllous forest in particular is highly threatened. Moreover, both habitat types are poorly represented within protected areas.

Nomenclatural Notes:— The sheet containing the lectotype bears two specimens, Deplanche 338, and Deplanche 340, one in flower and one in fruit. Although no information is given on the sheet as to which specimen relates to which collector number, separate sheets of Deplanche 340 held at NY and P are fruiting specimens. It is highly probable, therefore, that the fruiting specimen of sheet 338/ 340 is specimen no. 340, and the flowering one no. 338. The flowering specimen is selected as the lectotype on the basis of being housed in the institution at which the author was based, and there being known duplicates at three additional institutions (K, L, NY), and upon it being a flowering specimen, which is more taxonomically informative than the fruiting specimen.

Regarding the species epithet ‘ deverdiana ’, the correct spelling for this name should be ‘ deverdianum ’, as it is an adjectival epithet based on a geographical location, and the ending should therefore agree with the genus ending.

The specimen Deplanche 558 may be incorrectly numbered, on the basis that the number on the specimen label has been crossed out by an unknown individual.

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 5. Distribution of M. montrouzieri

FIGURE 6. M. montrouzieri: 6a, c. leaves (Clark, R.P. 150, 160); 6b. young inflorescence (Clark, R.P. 160); 6d, e. inflorescences (Clark, R.P. 137, 150); 6f. fruit (Clark, R.P. 150)