Swartzia lanata Torke & Mansano

Torke, B.M. & Mansano, V..F. 2013. Increments to the genus Swartzia (Leguminosae) from the southern Amazonian Craton. Kew Bulletin 68: 269. https://doi.org/10.1007/s12225-013-9442-4

Type

Type: Brazil, Pará, Mun. Marabá, Rio Itacaiunas, tributary of Rio Tocantins, Serra Buritirama, 5°30'S, 50°15'W, June 1970, fl, J. M. Pires & R. P. Belem 12269 (holotype RB-452826!; isotype IAN!).

Morphology General Habit

Small tree exceeding 5 m; trunk to c. 10 cm in diam.; pubescence of erect or appressed, straight, wavy or twisting, white or tan, elongate hairs, some rather like fungal hyphae, these frequently over 1 mm long; leaf-bearing portion of branches 5 – 13 mm thick at middle of internodes, densely whitish-lanate or sericeous, glabrescent

Morphology Leaves

Leaves imparipinnate, with 6 – 7 pairs of opposite lateral leaflets; stipules c. 20 – 40 × 5 – 10 mm, ovate-lanceolate to narrowly triangular, glabrous adaxially, densely lanate to sericeous abaxially, sometimes glabrescent, parallel-reticulate veined; petioles 10 – 20 cm long, 3.2 – 6.4 mm thick at middle, basally pulvinate, terete to subterete, unwinged, densely whitish-lanate to sericeous, glabrescent, the pulvinus c. 7 – 12 × 6 – 8 mm, terete, basally dilated, often obscured by dense pubescence; rachis 24 – 40 cm long, 1.5 – 5.5 mm thick at middle of segments, terete to subterete, often longitudinally bicarinate adaxially, sulcate between ridges, densely whitish-lanate to sericeous, glabrescent; stipels 0.5 – 1.6 × 0.3 – 0.8 mm, triangular, sometimes caducous; petiolules 2.9 – 10.5 × 2 – 4 mm, pulvinular, cylindrical, adaxially canaliculate, densely whitish-lanate to sericeous, glabrescent; laminas 2 – 4.7 × longer than wide, 12 – 32 × 4 – 11 cm, thickly chartaceous, oblanceolate, oblong-elliptic, elliptic, or obovate, the medial or distal ones largest and most elongate, the base acute to obtuse, the apex usually gradually to abruptly acuminate or more or less rounded, the acumen when present usually pointed, the adaxial surface lustrous, mostly glabrous, sometimes sericeous or lanate on midrib at base, the abaxial surface densely whitish sericeous to floccose-lanate, glabrescent, the midrib and secondary veins impressed adaxially, the higher order veins more or less immersed adaxially, all venation salient abaxially, the secondary veins c. 15 on each side of midrib, most ascending initially at 25° – 40°, gradually curving upward toward margin, often forming loose submarginal loops, particularly in distal half of leaflet, with included intersecondary veins semi-parallel to secondaries but less ascending

Morphology Reproductive morphology Inflorescences

Inflorescences simple racemes, borne from nodes on defoliate portion of branches or on trunk, to c. 60-flowered, the flowers spirally arranged, unopened ones densely clustered distally on inflorescence; axis 10 – 28 cm long, 3 – 4.9 mm thick near base, terete, densely tawny-pilose to lanate; bracts 6.3 – 12.8 × 2.9 – 5.6 mm, ovate to elliptic, abaxially convex, apically acuminate to narrowly acute, basally truncate, glabrous adaxially, densely sericeous to pilose abaxially; pedicels 16 – 24 mm long, 1.3 – 2 mm thick at middle, terete, densely tawny-pilose to lanate; bracteoles lacking; flower buds 8.2 – 10.5 × 7.7 – 10.6 mm, globose to somewhat ellipsoid or oblate, weakly umbonate, densely tawny-pilose

Morphology Reproductive morphology Flowers Calyx

Calyx mostly glabrous adaxially, but villous centrally at insertion of stamens, densely tawny-lanate to tomentose abaxially, sub-actinomorphic, entire in bud, splitting irregularly; segments 4 – 5 in number, c. 6 – 10 × 4.5 – 9 mm, subequal, more or less elliptic, recurved

Morphology Reproductive morphology Flowers Corolla

Corolla monopetalous; petal adaxial, yellow, patchily sericeous on claw and base of veins abaxially, the claw 2.5 – 2.8 mm long, 0.4 – 0.8 mm wide at base, 1.3 – 2.1 mm wide at apex, clavate, the limb 18.2 – 22.5 × 16.8 – 19.1 mm, ovate, basally obtuse to truncate, apically rounded, the venation subpalmate with 7 – 9 pairs of primary veins, the central vein more robust than others

Morphology Reproductive morphology Flowers Androecium

Androecium glabrous, strongly zygomorphic, the stamens dimorphic, of two size classes; outermost abaxial stamens larger than others, 6 – 9 in number, the filaments c. 22 – 23 mm long, 0.1 – 0.2 mm thick at middle, golden-yellow, dorso-ventrally compressed, tapering apically, the anthers c. 4.7 × 1.3 mm, oblong in outline, the connective obtuse to broadly acute apically, usually somewhat prolonged beyond thecae; smaller stamens c. 160, adaxial to central on floral axis, the filaments 9.5 – 15.5 × 0.1 – 0.2 mm, golden-yellow, terete to elliptic in cross section, the anthers 1.8 – 3.1 × 0.8 – 1 mm, brown, oblong-elliptic in outline, the connective obtuse to broadly acute, usually somewhat prolonged beyond thecae

Morphology Reproductive morphology Flowers Gynoecium

Gynoecium unicarpellate; stipe 5 – 8 mm long, 1 – 1.4 mm thick at middle, more or less terete, densely lanate; ovary 9 – 11.5 × 2.3 – 2.7 mm, arcuate-filiform, densely lanate, the locule glabrous; ovules c. 15; style 0.9 – 1.5 × c. 0.5 mm, terminal, terete, basally villous, apically glabrous; stigma truncate

Morphology Reproductive morphology Fruits

Mature fruits not seen; immature fruits with the stipe c. 11.5 × 1.4 mm, terete, densely lanate, the body c. 6 × 1.3 cm, falcate-lanceolate, narrowly acute at base and apex, laterally compressed, swollen at ellipsoidal seed chamber, probably moniliform in multi-seeded fruits, tomentose-villous, glabrescent

Note

A many-flowered inflorescence with a robust axis, ebracteolate pedicels, a yellow petal with the base of the limb obtuse or truncate, an elongate gynoecium with the stipe and style much shorter than the ovary, and a truncate stigma belie a close relationship between the new species and several species of Swartzia section Terminales (R. S. Cowan) Torke & Mansano, to which it is assigned; in the context of the section, it is unique in the following combination of characters: lateral leaflets 6 – 7-paired, each with the undersurface densely sericeous to floccose-lanate and the midrib impressed on the upper surface, stipules 2 – 4 cm long, inflorescence axes densely pilose-lanate, bracts 6.3 – 12.8 mm long, pedicels 16 – 24 mm long, flower buds 8.2 – 10.5 × 7.7 – 10.6 mm, densely pilose, larger stamens 6 – 9, ovary 9 – 11.5 × 2.3 – 2.7 mm, densely lanate, the locule glabrous.

Swartzia lanata belongs to section Terminales, a group of about 30 species that is highly diversified in Amazonia. The Amazonian members of the section are characterised by ebracteolate pedicels, a yellow petal and elongate gynoecia, often with the stipe and style relatively reduced, and moniliform fruits. Within the section, the new species is most closely allied to a taxonomically challenging complex that includes species such as S. costata (Rusby) R. S. Cowan, S. fugax Benth., S. laurifoliaBenth., S. leptopetalaBenth., and S. mangabalensis R. S. Cowan, but it is easily separated from these and other similar species by multiple diagnostic differences (Table 3), most notably its relatively more numerous leaflets, which are densely sericeo-lanate on the lower surface. The trichomes that make up the leaflet indument often exceed 1 mm in length and are among the longest to be found on vegetative organs in any species of the genus.

Two separate collections made by Pires and Belém in March and June of the same year, respectively, were both numbered 12269 in Pires’ number series. Only the latter collection is treated as the type.

The specific epithet refers to the wooly pubescence that covers the young stems, leaf stalks and leaflet undersurface.

Distribution

Swartzia lanata is known only from the basin of the Rio Itacaiunas on the eastern flank of the Serra dos Carajás in southeastern Pará. Map 2.

Ecology

Based on current knowledge, the species appears to be restricted to upland terra firme sites and may be associated with outcrops of manganese and copper bearing rock. One collection is from liana forest.

Conservation

Swartzia lanata is assigned to the IUCN Red List category of Vulnerable (VU), based on application of criterion B1. The species is known from only two localities. Its possible association with serpentine substrates leads us to speculate that the extent of occurrence is less than 20,000 km2. Continuing decline is suggested by the fact that the known distribution lies within a region at the heart of industrial-scale mining for manganese, copper, gold, and rare minerals. Much of this region has undergone rapid settlement and deforestation, however a large block of mostly intact forest, where the species is to be expected, is nominally protected as the Carajás, Itacaiunas and Tapirapé-Aquiri National Forests, the Tapirapé Biological Reserve and the Xikrin do Rio Catete Indigenous Area.

Phenology

Flowering collections have been made in June and July.