NEW CALEDONIA. Province Sud, Tontouta, 21°57.9336'S; 166°14.9166'E, pousse dans l’ombre, à la base des arbustes, fleurs blanches, 15 Apr 2004, fl., fr., M. Pignal 2245 (holotype, P! [P02288351]; isotypes HUEFS! [243158], K!, NOU!).

Ab aliis speciecibus Indigoferarum Novae-Caledoniae species nova facile differt fruticoso virgato habitu, foliis cum 7–11 foliolis oppositis, late obovalibus vel orbiculatis apice emarginato, nervatione obsolescenti, margine revoluto, pagina infera cinareo-albida, floribus 8–10 mm longis petalis plerumque albis.

Virgate shrub or subshrub, 0.5–2.5 m high, with slender and thin stems, young stems flexuous, with short internodes (sometimes up to 3 mm long) at the base, slightly quadrangular becoming terete; indumentum of young branches and leaves of straight, white, adpressed T-shaped hairs. Stipules 1–1.5 × 0.4–0.5 mm, narrowly triangular to falciform, pubescent. Leaves 3–6 cm long, pinnate, (5–)7–11-foliolate, sometimes 3-foliolate towards the base of the stem; petiole furrowed, 5–12 × c. 0.6 mm; rachis furrowed, quadrangular in cross section, articulated, thick black multicellular hairs (colleters) at the leaflets attachments, segments 3–7 mm long; stipels 0.1–0.5 × c. 0.2 mm, brown, thick, forming the 2 lateral apices of the rachis articles; leaflets opposite, widely obovate to orbicular, dark green above, greyish to whitish pale green below, base rounded to obtuse, apex mostly emarginate, rarely rounded, mucronate, the mucron c. 0.2 mm long, brown, margin entire, slightly revolute, secondary veins 2–5, brochidodromous, invisible adaxially, obscure to invisible abaxially; terminal leaflet 7–17 × 6–12 mm, lateral leaflets (4–)9–12 × 4–6 mm; petiolules 0.6–1.5 mm long, of the same color as the rachis. Inflorescence a 5–7 cm long raceme (6–13 cm long in fruiting state); peduncle 10–15 mm long, pubescent; bracts 1.1–8 mm long, triangular, shortly acuminate, pubescent; pedicel 2–3 × 0.2–0.25 mm. Flower 8–10 mm long; calyx 2–2.5 mm long, campanulate, asymmetrical, 5-lobed, the vexillary (upper) lobes shorter and deltoid, the carinal (lower) lobe longer and acuminate; petals white, sometimes tinged with pink, never red, standard petal c. 8–9.4 × 4.5–5 mm, elliptical or ovate, apex emarginate, pubescent outside with appressed T-shaped hairs, wing petals c. 7–7.5 × 1.5–2.5 mm, slightly shorter than the keel, narrowly obovate to oblong-linear, apex rounded, keel petals 7–9 × 2–2.5 mm, narrowly obovate, spathulate, apex rounded, valvately connate along the lower margin halfway to the tip; androecium diadelphous (9 stamens fused and the vexillary one free), staminal tube 7.5–9 × c. 2 mm; ovary c. 6-ovulate, c. 5.5 mm long, sessile, glabrous, style c. 3.5 mm long, hook-shaped at apex (hook c. 1.2 mm), stigma capitate. Pod 27–38 × c. 3 mm, straight, linear, apex acuminate by 2–4 mm, indehiscent or late dehiscent; valves reddish brown in the living plants, glabrescent or with white appressed T-shaped hairs. Seeds 2–4, c. 2.5 × 1.2–1.5 mm, rectangular; testa black.

Indigoferamonieriana occurs in shrubby maquis vegetation or low forests on schisto-serpentine soil or ferritic soil. It is found in low altitudes on coastal formations from sea level up to about 700 m. Although it occurs in an open environment, it grows under the shadow of higher bushes (See Fig. 2). Coastal formations, especially sclerophyll forests, have greatly reduced (Bouchet et al. 1995, Jaffré et al. 2002).

Flowering from January to March, fruiting from May to November.

This species is dedicated to Louis-Guillaume Lemonnier (1717–1799), “associé de l’Institut, ci-devant membre de l’Académie des sciences, conseiller d’État honoraire, et premier médecin du Roi” (Cuvier 1861) [Associate of the French Institute, former member of the Academy of Sciences, Honorary State Councilor, and First Physician of the King] who herborised with C. Linnæus, J.-J. Rousseau, Antoine and Bernard de Jussieu. We adopt the spelling “Monier” used by J.-B. Fusée Aublet in his herbarium kept at the Paris Museum and known as “Jean-Jacques Rousseau herbarium” (P-JJR), from the name of its most famous owner.

Indigoferamonieriana was provisionally assessed as vulnerable based on IUCN (2017) criterium B as it presents a restricted EOO (7070 km²) and AOO (32 km²), and its estimated range covers about half of New Caledonia’s main island.

Guillaumin (1936) noted that several virgate specimens from New Caledonia could not be reported to the typical Indigoferaaustralis and he preferred to determine them as I.australisvar.gracilis DC. However, a careful examination of the type collection of this variety (Sieber Fl. Novae. Holl. 380, G, K, P) shows that the New Caledonian material is clearly distinguished from I.australis by the less numerous leaflets (5–9 vs. 17–25 in I.australis), mostly obovate with an emarginate apex, lower surface whitish or greyish green and inconspicuous venation (vs. leaflets mostly elliptical with acute to rounded apex, green lower surface and raised venation; see Table 1 for further distinctive characters). Besides, I.australis is restricted to Australia and, although presenting a broad morphological variation (Wilson and Rowe 2010), its diagnostic features do not overlap with I.monieriana. The new taxon is also remarkable for its articulate leaf rachis and its dark ferruginous colleters (multicellular thick secretory hairs) at the insertion of petiolules on the rachis.

NEW CALEDONIA. Province Nord: Arbrisseau de 2–3 m de hauteur, NaKéti [=Nakety], sur les collines schisto-serpentineuses, [21°32.814'S; 166°2.532'E], Oct 1869, fr., B. Balansa 2471 (P [P03615799, P03615800]); Mont Poumé [=Poum], [20°15.282'S, 164°1.584'E], May 1871, fr., B. Balansa 3332 (P [P03615852, P03615853]; Village de Voh, [20°59.055'S, 164°39.3881'E], 25 Jul 2015, fr., D. Fleurot 53 (P [P00993550]); Kaala-Gomen, Taom, au-dessus de l’ancienne carrière, Mt. Homédéboa, 720 m, maquis arbustif, sol ferrallitique ferritique sur pente forte érodée, [20°46.998'S, 164°34.002'E], 16 Jan 2007, fl., R. Barrière & F. Rigault 71 (NOU [NOU016084]); Village de Voh, Tribu de Gatope, presqu’île de Gatope, forêt de 2 à 4 m de hauteur à Terminalia et Homalium, [20°59.148'S, 164°40.368'E], 17 Nov 2004, fr., J.-N. Labat et al. 3511 (P [P00454773]; Voh, Vavoutou, forêt sèche, 10 m, [21°0.45'S, 164°41.283'E], 18 Nov 2009, fr., J.-N. Labat et al. 4050 (P [P00749569]; Voh, Gatope, presqu’île de Gatope, maquis minier. Serpentine. Strate inférieure, [20°59.683'S, 164°40.133'E], 20 Nov 2009, fr., J.-N. Labat et al. 4082 (NOU, P [P00749614]; Au-dessus de Gomen, Mt. Kaala, 500–700 m, maquis sur pente raide serpentineuse, [20°38.55'S, 164°23.448'E], 18 Mar 1966, fl., H.S. MacKee 14586 (NOU [NOU070814], P [P03615845, P03615846, P03615847]; Pente S Mt. Kaala, [20°38.55'S, 164°23.448'E], 27 Mar 1980, fl. H.S. MacKee 37971 (NOU [NOU070811], P [P03055971]); suffrutex 0,5 met, Montagne de Gomouen, Gatope, [20°58.014'S, 164°39.786'E],1867, fl, fr., E. Vieillard 2535 (P [P00888525 to P00888532]); Province Sud:Collines ferrugineuses situées à l’embouchure du Dotio [=Dothio], [21°36.882'S, 166°12.684'E], 1 Nov 1870, fr, B. Balansa 3003 (P [P03615854, P03615855], MO); Tontouta: col de Mo, 400 m [c. 21°58'S, 166°11'E], 27 Jan. 1969, fr, H.S. MacKee 20168 (P [P00888523]); Tontouta [c. 21°58'S, 166°11'E], 25 Dec. 1971, fr, H.S. MacKee 24758 (P [P03615805]); Basse Tontouta (rive gauche) [c. 21°58'S, 166°11'E], 14 Jan. 1982, fl., H.S. MacKee 40197 (P [P03615806]) .