Inga loubryana Poncy, 2007

Poncy, Odile, 2007, A new species of Inga Mill. (Fabaceae, Mimosoideae) from the Guianas, Adansonia (3) 29 (2), pp. 249-254 : 250-253

Inga loubryana Poncy , sp. nov.

( Figs 1 ; 2 )

Arbor grandis , ad sectionem Leptingam pertinens, Ingae paraensis Ducke affinis sed praecipue differt minoribus floribus, cum campanulato calyce et infundibuliformi corolla, atque fructu amplo, sinuatis crassis prominentibusque suturis munito.

TYPUS. — French Guiana. Sinnamary , Piste de St-Elie, PK 19, 11. V.1991, fl., Loubry 1135 (holo-, P; iso-, CAY, US).

PARATYPES. — French Guiana. Montagne de la Mirande , IV.1951, fl., SF 3766 ( P). — Mont Grand Matoury , 4°52’N, 52°21’W , 12.X.1995, fr., Poncy 993 ( P). — “Cayenne” , 31.XII.1955, fr., Béna, SF (BAFOG) 1105 ( P, U). — Paracou , 5°3’N, 52°80’W , 30.VI .2000 , fl., Pétronelli 221 (CAY, P). — Sinnamary , Piste de St-Elie, 13.V .1991 , fl., Sabatier 3570 (CAY, NY, P). — St-Laurentdu-Maroni, Route de l’Acarouany , km 1,1, 14.I .1957 , fr., SF 7650 (NY, P, U). — St-Laurent-du-Maroni, Route de Mana , 9.I .1945 , fr., SF 7145 (CAY, NY, P, U). — Ibid ., 4.IV.1956, fr., SF 7437 ( CAY, NY, P, U) .

Guyana. Bartica , Moraballi Creek , 1.X.1939, fr., Fanshawe 259 (= FD 2995) ( FDG, K, U). — Mazaruni, Puruni Riv., Takutu Creek, 4.XII.1944, fr., Fanshawe 2136 (= FD 4872) ( BRG, K, NY). — Potaro Riv., Mahdia Riv., 16. I .1943, fr., Fanshawe 1038 (= FD 3774) ( FDG, K) .

OTHER MATERIAL EXAMINED. — French Guiana. Gourdonville , 18.VIII.1914, old infl., Benoist 1551 ( P, NY, U). — St-Laurent-du-Maroni, 14.IV.1961, fl., Aubréville 253 ( P). — Ibid., Route de Mana, 7. I.1946, fr. immat., SF 7139 ( P, U). — Ibid. , 10. I.1956, fr. (carp. coll. not seen), SF 7148 ( P). — Ibid. , Route de Cayenne, trace de l’abattis Bonnol, 22.VIII.1956, fl ., SF 7539 ( CAY, NY, P). — Ibid. , 14.XI.1956, fr., (carp. coll. not seen) , SF 7598 ( P, U). — Ibid. , Route de Charvein à l’Acarouany, 15.VII.1953, old fl ., SF 16 M ( P, U). — Ibid. , Route de Cayenne, chantier FOSMA, scierie Margot , fr. immat., 1.XII.1953 , SF 116 M ( P, U). — Sinnamary , Piste de St-Elie, 5°20’N, 53°W, 27.VII.1991, fl., Sabatier & Prévost 3652 ( CAY, NY, P, U, US). — Ibid., immat. inflorescence, Sabatier & Prévost 3654 ( CAY, NY, P, U, US). — Ibid., same tree as the former, immature pod, Sabatier & Prévost 3948 ( CAY, P). — Ibid., km 15.7, 5°17’N, 53°3’W, 21.VIII.2002, fl., Prévost & Sabatier 4554 ( CAY, K, NY, P) .

DESCRIPTION

Middle-sized to large trees, up to 35 m high and 70 cm in diameter. Trunk irregular, without buttresses. Outer bark lenticellate, reddish brown. Branchlets lenticellate, even the youngest ones, the latter glabrous or brownish pubescent. Lenticels whitish, thin, longitudinally elongated.

Leaves paripinnately compound with 2 or 3 pairs of leaflets. Stipules linear, 2-3 mm long, caducous. Petiole and rachis not winged, cylindrical or flattened and slightly canaliculate, lignified and lenticellate on old leaves, glabrous or with sparse light hairs. Petiole 1-2(+) cm long, rachis segments approximately twice as long (2-4 cm). Foliar nectaries generally conspicuous, orbicular, the border thick, sessile or shortly stipitate (occasionally markedly stipitate), the distal one sometimes lacking. Petiolule reduced to pulvinus, black, 2-3 mm long. Leaflets elliptic, the proximal ones 5.5-8.5 × 2-3.5 cm, the distal ones (7.5-)9-13 × (2.5-)3-5(-6) cm, base cuneate to attenuate, apex acute, sometimes with a short and wide acumen (c. 6 × 5 mm), mucronate. Venation camptodromous. Blades variable in aspect, typically chartaceous, often discoloured, dark green above, paler and greyish below, the primary vein prominent on both faces. In some samples (“glossy inga”), inferior surface very smooth, glossy, looking densely and tiny dotted, the secondary veins not prominent.

Inflorescences umbellate, 1-3 axillary to adult leaves or young leaves of new growth units. Peduncle (1-)2-4(-5) cm long, glabrous or puberulous. Rachis globose or shortly clavate, c. 2 mm diam., 15-20-flowered, on some specimens with a linear bract 2-3 mm long near or at base of the umbel. Floral bracts scaly, curved, navicular or spatuliform, 1.5-2 mm long, puberulent, persistent. Pedicel slen- der, 3-6 mm long. Calyx narrowly campanulate, 1-1.5 mm long, the teeth inconspicuous, often irregular, puberulent. Corolla 5-6(-7) mm long, glabrous, funnelform. Staminal tube exserted up to 3 mm from the corolla. Ovary glabrous, ovules 15-20, stigma narrowly cup-shaped.

Fruit a large and robust pod, up to 40 × 4 cm, 10- 20-seeded, the valves shallowly transversally wrinkled, the sutures subligneous and thickened up to 5 mm at maturity, undulating around seeds.Seeds not contiguous, prominent at maturity, up to 2.5 × 1.5 cm.

ETYMOLOGY

The species is named in honour of Denis Loubry, who first collected excellent flowering materials at Piste de St-Elie.

DISTRIBUTION RANGE AND HABITAT

Dense evergreen rainforest in northern French Guiana and Guyana, on white sand or laterite. Not recorded from Suriname.

NOTE ABOUT THE MORPHOLOGICAL VARIATION wITHIN THE SPECIES

The present delimitation of Inga loubryana is mainly based on flower and fruit characters, that distinguish it from the close species I. paraensis , after the following key:

— Calyx <2 mm, corolla ≤ 7 mm; staminal tube exserted; mature pod up to 40 × 4 cm, margins subligneous and thickened, undulating around seeds, those not contiguous ..... .............................................................................................................. Inga loubryana

— Calyx> 2 mm, corolla> 8 mm; staminal tube not exserted; mature pod up to 28 × 2.5 cm, straight, seeds contiguous ........................................................................ Inga paraensis

The typical leaf of I. loubryana (mostly bijugate) differs from that of I. paraensis (mostly trijugate) by its less marked petiolule, its narrower leaflets, with a cuneate base, venation not prominent adaxially, the nerves prolongating marginally towards the apex.

As it is usually the case in the genus, and given the vegetative variability, sterile or poorly fertile materials (old inflorescences, or immature fruits) may be difficult to assign with certainty to a particular species. Awaiting more informative collections, we include here several specimens that show minor leaf variation against the typical series (“ paratypes ”) and list them separately (“other material examined”). Some of them represent the form mentioned before as “inga vernissé” (= “glossy inga”) after the particular texture of leaflets. This form remains poorly known, so far the only few fertile specimens available have too young inflorescences or pods to be assigned with certainty to I. loubryana . However the tree proves to be locally abundant at the study site of Piste de St-Elie station, French Guiana. The difficulty to obtain fertile materials, in a plotted area where labelled trees are regularly visited, is informative about its phenology, suggesting that the species flowers very rarely. According to D. Loubry’s phenological observations, the trees are deciduous.

Lastly, potentially distinct inflorescential characters are visible on the specimen Prévost & Sabatier 4554, but this collection has old wilted inflorescences.

The present provisional delimitation of I. loubryana therefore includes some morphological variation, further collections may confirm this variability but they may lead us to recognize two distinct species.

Figures

FIG. 1. — Inga loubryana Poncy: A, habit; B, stipules; C, foliar nectary; D, base of umbel; E, flower; F, stigma; G, H, stamens; I, pod. Scale bars: A, 2 cm; B, C, 2 mm; D, 1 mm; E, 4 mm; F-H, 0.5 mm; I, 3 cm. A-H, Loubry 1135; I, Béna 1105.

FIG. 2. — Inga loubryana Poncy, herbarium specimen Fanshawe 2136 (= FD 4872) (Guyana).