Swartzia ingens Barneby

Description

Authors: Benjamin M. Torke and Vidal de Freitas Mansano

Type: Brazil, Mun. Oriximiná, margem esquerda do Rio Trombetas, próximo ao Vicinal ES-9 da estrada entre Cachoeira Porteira e o Perimetral Norte, 24 Nov 1987 (fl), C. A. Cid Ferreira et al. 9664 (holotype: INPA; isotypes: K, MG, NY, RB, US).

Description: Tree to ca. 10 m; trunk to ca. 15 cm in diameter young branchlets thinly to somewhat densely strigulose, glabrescent Leaves imparipinnate, or, not uncommonly, paripinnate by abortion of the terminal leaflet, with 3-6 pairs of opposite to subopposite lateral leaflets; stiplules ca. 0.6 x 0.3, triangular, sparsely strigulose adaxially, caducous; petiole 1.2-2.5 cm, unwinged, glabrous to sparsely strigulose, the pulvinus 3-13 mm; rachis 8-45 cm, unwinged, often longitudinally bicarinate adaxially, glabrous to thinly strigulose; stipels unknown, apparently caducous; petiolules 4.5-9.6 mm, essentially glabrous; leaflet blades 1.6-2.7 x longer than wide, 6.5-22 x 3-22 cm, thickly chartaceous, elliptic to weakly obovate, the margin decurved or somewhat revolute, the base acute to obtuse-rounded, the apex shortly caudo-acuminate, the acumen pointed or rounded, 3-17 mm long, the adaxial surface glabrous, the abaxial surface often more or less glaucous or canescent, minutely malpighio-strigulose, the trichomes deciduous but the bases persistent, the midrib usually at least somewhat raised-cariniform adaxially, raised abaxially, other venation raised to immersed on both surfaces, the secondary veins 8-12, initially ascending at 16-31°, forming loose submarginal loops, these with several included intersecondary veins semiparallel to secondaries but less ascending. Inflorescences usually simple racemes, rarely one-branched, borne from axils of coeval leaves or from slightly older defoliate portion of branchlets, to ca. 35-flowered; axes 7-16 cm, thinly to somewhat densely golden-strigulose; bracts 0.9-1.5 x 0.6-0.8 mm, triangular to ovate, strigulose abaxially; pedicels 12-17.2 mm, dorso-ventrally compressed, thinly to somewhat densely golden-strigulose; bracteoles 0.5-1 mm, inserted in distal half of pedicel, triangular to ovate-lanceolate, opposite to strongly subopposite; flower buds 8.3-10.9 x 6.2-8.3 mm, ellipsoid, weakly umbonate, mostly glabrous, sometimes strigulose at extreme base. Calyx segments 3-4 in number, 8.2-12.7 x 4.2-9.6 mm, subequal, elliptic or irregularly shaped, strongly recurved, entirely or essentially glabrous. Petal yellow, glabrous; claw 4.6-4.8 mm; limb 12-15.5 x 11.8-14.2 mm, broadly ovate to elliptic, the base truncate to obtuse. Stamens yellow, glabrous, essentially dimorphic, most clearly of two size categories, but usually with a few intermediate; larger stamens 11-14, adaxial, the filaments 17.4-23.2 mm, somewhat dorso-ventrally compressed basally, tapering apically, the anthers 1.3-1.8 x 1-1.1 mm, elliptic to oblong in outline; smaller stamens ca. 180, the filaments 4.5-14.3 mm, the anthers 0.9-1.4 x 0.7-0.9 mm, elliptic to oblong in outline. Gynoecium green, glabrous; stipe 16.5-18.9 mm; ovary 6.8-8.2 x 2.2-3 mm, inequilaterally arcuate-elliptic in outline, laterally compressed, the locule glabrous; ovules ca. 10-13; style 1.5-2.4 mm, obliquely terminal, apically tapering, usually somewhat down-curved; stigma punctiform; Mature fruits unknown; immature fruits (with seeds not yet enlarged) purplish, glabrous, the stipe 1.9-2.2 cm, the body 2.9-3.4 x 1.2-1.4 cm, elliptic in outline, laterally flattened, broadly acute at base, rounded at apex, obliquely apiculate by persistent style.

Common names: No common names have been recorded.

Geographic distribution: Swartzia ingens is known from only five collections from the central drainage of the Trombetas River, a northerly black-water tributary of the Amazon River in northwestern Pará, Brazil.

Ecology: The species has been collected in "terra firme" rainforest, in one case growing over rocky outcrops, and also in seasonally inundated riverine "igapó" forest. Nothing else is known of its ecology.

Phenology: Flowering may be sporadic or with more than a single annual peak. Flowers have been collected in November, immature fruits in June.

Taxonomic notes: Malpighian trichomes, caudo-acuminate leaflets, bracteolate pedicels, a yellow petal with the limb basally acute to truncate, and a glabrous gynoecium with the stipe much longer than the narrowly elliptic ovary, which in turn is substantially longer than the style all point to a close relationship between S. ingens and the core members of S. section Recurvae, to which it was assigned by Torke and Mansano (2009). Among these species, S. ingens is diagnosed by the combination of 3-6-jugate leaves with an unwinged rachis, relatively large, decurved or revolute margined leaflets, relatively small stipules, bracts and bracteoles, and large, glabrous flower buds contrasting with golden strigulose inflorescence axes and pedicels. The frequently glaucous, but glabrous to sparsely strigulose lower leaflet surface is also characteristic. Barneby's (1992) speculation about a potentially close relationship with S. lucida, a species now included within sect. Unifoliolatae, is not supported in the majority of infrageneric characters. The citation of an isotype at MO in the protologue was apparently made in error, as no material of the type collection has been found in that herbarium. The distribution of S. ingens in the Trombetas drainage and perhaps adjacent black-water drainages, which flow southward from ancient granitic uplands of the Guiana Shield, exemplifies a pattern of endemism shared by several other species of the genus, including S. duckei of section Orthostylae, S. oriximinensis of section Recurvae (this a distantly related species with unifoliolate leaves), and an undescribed species of section Swartzia (Prance et al. 22235, 22253).

Uses: No uses have been recorded.

Etymology: Barneby (1992) adapted the specific epithet, meaning unusually large, in reference to the leaves.

Conservation status: Data are insufficient to make a definitive assessment. The basin of the Trombetas River where the species occurs is still largely covered by intact Amazonian ecosystems, but deforestation is spreading into the interior from the PA-254 road, and to a lesser extent, along the northern section of the BR-163. Swartzia ingens has been documented from or is likely to occur within the Trombetas and Faro State Forests, as well as the Rio Trombetas Biological Reserve.

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