Securidaca marajoara, C.S.Costa, A.C.A.Aguiar-Dias & A.O.Simoes, 2013

Costa, Christiane Silva Da, Aguiar-Dias, Ana Cristina Andrade De & Simões, André Olmos, 2013, Securidaca marajoara (Polygalaceae), a new species from the Brazilian Amazon, Phytotaxa 137 (1), pp. 53-56 : 54-55

Securidaca marajoara C. S. Costa, A. C. A. Aguiar-Dias & A. O. Simões, sp. nov. ( Fig. 1 ) .

Shrub, leaves coriaceous, blade ovate to elliptic, glossy at adaxial surface, opaque at abaxial surface, long and lax raceme, yellow flowers, large and conspicuous bracts, foliaceous, elliptic and sericeous, persistent at flower anthesis.

Type:— BRAZIL. Pará: Ilha de Marajó, Muaná , local chamado Jacarequara , campo aberto, baixio seco, campo temporariamente alagado, arbusto, 2 m alt., flor amarela, 21 January 2005, fl., A.S.L. da Silva et al. 4279 (holotype, MG! Isotype, INPA) .

Shrub, 2 m high. Branches terete, covered with short yellow erect trichomes; nodes with 2 glands lateral to the base of the petiole, umbonate, each gland 0.8–1.1 mm diam.; internodes 12–16 mm long. Leaves alternate; petiole 4.5–5.5 mm, pilose, trichomes short, adpress; blade coriaceous, ovate to elliptic, 3.8–5.6 × 2–2.6 cm, apex acute, base rounded, margin straight, glabrous to glabrescent, trichomes, when present, restricted to the base and close to the petiole, adaxial surface glossy, pilose only at the base of the primary vein, abaxial surface opaque, glabrescent, more densely along the primary vein; venation broquidodromous, primary vein slightly raised above and well visible below, secondary veins slightly raised on both surfaces. Raceme axillary or terminal, lax, 6.2–10.1 cm long; rachis angled to flat, pubescent, trichomes yellowish, short, dense and adpressed; pedicel 3–3.7 mm, sericeous, with umbonate to short terete glands attached to the base, 0.5–0.7 mm. Bracts and bracteoles persistent, sericeous, bracts foliaceous, 2.6–6.2 × 2.5–2.9 mm, bracteoles linear, 1.2–1.6 × 0.2–0.3 mm. Flowers yellow, 8.6–10.3 mm long. External sepals free from each other, adaxially pilose, ciliate, the upper sepals ovate, 3.8 × 2.6 mm, the lower sepal cimbiform, 5 × 3.5 mm. Internal sepals obovate with a short claw, adaxially pilose, ciliate, 9.5 × 6.2 mm, inflexed at the apex. Corolla with lateral petals spatulate, shortly unguiculate, ciliate, 7.8–8 × 3.6–3.7 mm, apex truncate. Rudimentary petals scalelike, about 0.3 mm long. Carina about 8.6 mm long, ciliate, cristate (unguicule: 2 mm long, cucule: 5.5 mm long, crest: 1.5 mm long). Stamens with a filament sheath about 7 mm long, fleshy, pilose at the base, margins and dorsal portion. Ovary 1 × 0.5 mm, gibbose, sessile, densely pubescent at the gibbous region and near the base, sessile; style 6.9 mm long, uncinate, glabrous, stigma bilobed. Fruits and seeds unknown.

Etymology:— The epithet of this new species refers to Marajó Island, where the only known specimen was collected.

Distribution and habitat: — Securidaca marajoara is known only for the type collection, from northern Brazil. It grows in the Amazon Rainforest, in riverine forests.

Phenology: —The species was collected during its flowering period in January. The fruiting period is unknown.

Notes:— Securidaca marajoara is characterized by its large and conspicuous bracts, persistent at flower anthesis, by its relatively long inflorescences (6.2–10.1 cm long), small, ovate to elliptic leaves (3.8–5.6 × 2– 2.6 cm) and short internodes (12–16 mm long). The species is sympatric and morphologically similar to S. bialata Bentham (1851: 162) , with similarities regarding the shape of the petiolar and pedicelar glands, leaf size, inflorescence size and architecture, and flower size. Despite their resemblance, the two species can be easily distinguished by the larger, persistent and elliptic bracts of S. marajoara .

Figures

FIGURE 1. A–L: Securidaca marajoara C. S. Costa, A. C. A. Aguiar-Dias & A. O. Simões, A. flowering branch, B. nodal gland, C. detail of inflorescence, depicting the large bracts at the base of flower buds, D. detail of flower, bract (Arrow) and persistent bracteoles, E. pedicelar glands, F–G. external sepals, H. internal sepal, I. lateral petal, J. carina, K. androecium, L. gynoecium (A–L A.S.L. da Silva et al. 4279).