Indigofera dumbeana M.Pignal & L.P.Queiroz, 2019

Pignal, Marc & Paganucci de Queiroz, Luciano, 2019, The genus Indigofera (Leguminosae) in New Caledonia: two new species and a key for the species, PhytoKeys 119, pp. 53-66 : 53

Indigofera dumbeana M.Pignal & L.P.Queiroz sp. nov. Figs 2 , 3 , 4b ; Table 1

Type.

NEW CALEDONIA. Province Nord, Bois des collines schisteuses près de l’embouchure de la Dumbéa, [22°9.7668'S, 166°26.4336'E], May 1870, bt, fl, B. Balansa 2807 (holotype: P! [P03615849], isotype, P! [P03615850]).

Diagnosis.

Indigoferae zollingerianae Miq. similis, floribus parvis (c. 4.5-6.5 mm longis) foliisque cum aliquot foliolis (11-23), sed brevioribus 10.5-11.3 cm longis foliis cum valde canaliculata rachidi, brevioribus plerumque 17-32 mm longis, ovatis vel obovatis (vs. elliptico-lanceolata) apice obtuso vel leviter emarginato, secundorum nervorum 6-7 paribus, (vs. 9-10 secundorum nervorum paria), fructu tantum 5-6 seminibus contiguis, ellipsoideisque, versus 23-26 cm longa folia leviter vel haud canalicalata rachidi, 35-85 mm longa elliptica vel lanceolata foliola acuminato apice, 9-10 secundorum nervorum paria atque circa 16 nuda in cumulo disposita semina), praecipue differt.

Description.

Small tree or shrub 3-5 m high, branches mostly plagiotropic and horizontal (Veillon 7138, P), young stems flexuous, quadrangular or terete, internodes 10-15 mm long (but c. 5 mm long for the flexuous parts); indumentum of young branches and leaves of straight, white, adpressed T-shaped hairs. Stipules 1-1.5 × c. 0.2 mm, narrowly triangular to falciform, pubescent. Leaves 10.5-11.3 cm long, pinnate, 15-19-foliolate; petiole 10-15 mm long, furrowed, sparsely pubescent; rachis yellowish to light brown, strongly furrowed, non articulated and with thin appressed hairs, thick brown multicellular hairs (colleters) at the leaflets attachments, segments at the leaflets attachments 10-14 mm long; stipels 0.2-0.3 mm long, setiform, early caducous, mostly absent; leaflets opposite, secondary veins visible on both sides of the lamina, upper and lower surfaces with dense, white hairs; terminal leaflet 27-34 × 15-19 mm, ovate to obovate, apex rounded to slightly emarginate, mucronate, base acute, secondary veins 7-12 pairs, lateral leaflets 20-17 × 12-14 mm, obovate, apex slightly emarginate, mucronate, secondary veins 6-7 pairs, petiolules 1.2-2 × 0.4-1.5 mm, dark brown on dry specimens, not furrowed. Inflorescence a c. 50 mm long raceme, with more than 40 flowers; peduncle pubescent, quadrangular, c. 10 mm long; pedicel c. 1.5 × 0.2 mm. Flower c. 6.5 mm long; calyx c. 1.5 mm long, campanulate, asymmetrical, 5-lobed, the vexillary (upper) lobes shorter and shallow deltoid, the carinal (lower) lobe longer and acuminate; petals white; standard petal c. 5-6 × 4.5 mm wide, obovate, apex slightly emarginate, pubescent outside with apressed T-shaped hairs; wing petals c. 4 × 1.5 mm, slightly shorter than the keel, narrowly obovate to oblong-linear, apex rounded; keel petals 5-5.5 × 2 mm, obovate, apex rounded, valvately connate along the lower margin halfway to the tip; androecium diadelphous (9 stamens fused and the vexillary one free), staminal tube c. 6 × 1.5 mm; ovary c. 5-ovulate, c. 5 mm long, sessile, glabrous, style c. 2.5 mm long, hook-shaped at apex, stigma capitate. Pod c. 38 × 3 mm, straight, linear, apex acuminate, indehiscent; valves brown, pubescent with appressed white T-shaped hairs. Seeds 5-7, c. 3.5 × 5 mm, ellipsoid; testa black.

Distribution and habitat.

Indigofera dumbeana grows in lowland forests, mostly in wood edges areas (fide Veillon 7138, P and Veillon 7482, P).

Phenology.

Flowering in March and April, fruiting in May to November.

Etymology.

The specific epithet refers to the Dumbéa River in the mouth of which B. Balansa collected the type material.

Conservation status.

We assessed I. dumbeana as endangered both because it presents small EOO (2358 km2) and AOO (20 km2), and it is located rather in sclerophyllous forests that are perhaps the most endangered formations in New Caledonia, especially at low elevation ( Bouchet et al. 1995). Additionally, this species is known by few and rather old collections which could indicate its rarity in the island.

Discussion.

We agree with B. Schrire who annotated in 2004 the P00379654 specimen (M. Debray 2296) as a new species allied to I. australis Willd. Specimens of Indigofera dumbeana were previously referred to I. australis by Guillaumin (1936). These species are clearly rendered distinct by the habit as I. dumbeana presents plagiotropical, almost horizontal branches, stipules triangular or asymmetrical and falciform (vs. linear), and flowers with a five lobate calyx and white petals (vs. flowers with a truncate calyx and pink to purple petals). Indigofera dumbeana is more similar to I. zollingeriana , both occurring as a tall shrub or small tree habit with plagiotropical branches, but they are clearly distinct by the fruit straight with rectangular seeds linearly arranged (vs. fruit sinuous with transversely compressed seeds arranged like a stack of coins in I. zollingeriana ). Additionally, they present important differences in leaf and flower traits as presented in Table 1 .

Paratypes.

NEW CALEDONIA. Tronc grêle, hauteur 4 m, cime légère, croissant en massifs, 200 mètres au dessus du niveau de la mer, localisé, s.d., fr., I. Pancher s.n. (P! [P03615856]); Province Nord: Forêt derrière Ouéholle, [20°35.316'S, 164°31.464'E], 17 Aug 1967, fr, A. Nothis 440 (NOU [NOU070806], P! [P02851253]); Pouembout: commun, localisé en lisière de forêt, forêt plate, vers 500 m, forêt dense de moyenne altitude, substrat schistes, [21°1.998'S, 164°49.002'E], 18 June 1992, fr., J.-M. Veillon 7482 (NOU [NOU070809], P! [P02851258, P02851259]); Province Sud: Tontouta [c. 22S; c. 166°13'E], 29 Sept. 1975, fr, M. Debray 2296 (NOU, P [P00379654]; Sur un monticule de la région de Païta, [22°7.95'S, 166°22.566'E], s.d., fr, I. Pancher (Mus. Néocal. 177) (P! [P00888524, P03615848, P03615857]); sur les monticules argilo-schisteux de Païta, [22°7.95'S, 166°22.566'E], s.d., fr, I. Pancher s.n. (P [P03615844]; Nakutakoin: vallée au sud du pic Jacob, exposition S.W, vers 300 m, en lisière de forêt vallicole (vu aussi à l’intérieur), substrat phtanites, sol brun, [22°0.9'S; 166°25.002'E], 24 Aug 1989, fr., J.-M. Veillon 7138 (P [P03567480, P03615801], NOU [NOU070810]).

Figures

Figure 2. Map of the New Caledonia archipelago showing the major vegetation types (from Jaffre et al. 2012) and the distribution of the new species Indigofera monieriana and I. dumbeana.

Figure 3. Indigofera dumbeana sp. nov. a Flowering branch b Calyx (open) c Standard petal d Wing petal e Keel petals f Gynoecium g Fruit h Seeds a-f after Balansa 2807 g-h after Nothis 440. Drawn by Felipe Santos.

Figure 4. Leaflets comparison of the two new New Caledonian species of Indigofera in and their most related species. a Indigofera monieriana (M. Pignal 2245) b I. dumbeana (B. Balansa 2807) c I. zollingeriana (B. Balansa 1222) d I. australis (C. Walter s. n.). Left: adaxial surface, right: abaxial surface. Scale bar: 1 cm.