Corresponding author: Pedro Acevedo-Rodríguez (
Academic editor: Hanno Schaefer
The new genus
While working on a treatment of
A.
Small trees or shrubs. Stipules wanting. Leaves alternate, trifoliolate; leaflets serrate. Flowers solitary, axillary or in short racemes, actinomorphic, unisexual with staminate flowers sometimes bearing a rudimentary 2-locular gynoecium; pedicels elongated, non-articulate; calyx 4-merous, sepals of similar length, in two whorls; petals wanting; disc cupular; stamens (5)6, the filaments slightly of unequal length, connate at base, ovary 2-locular, with a single ovule per locule. Fruit of 1–2 basally connate, indehiscent monocarps, with fleshy exocarp, and a semi-woody endocarp; seeds exarillate, with papery testa.
One species, known only from Guyana and Brazil (Roraima).
1 | Flowers actinomorphic, apetalous, solitary, or in short axillary racemes; nectary disc cupular; pedicel non-articulate, >4 times as long as the calyx; pollen 4- to 5-porate , 4- or 5-angled in polar view |
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– | Flowers zygomorphic, petaliferous, on lateral cincinni in a racemiform or paniculate thyrse; nectary disc unilateral, semi-annular, 2- to 4-lobed, or rarely annular; pedicels articulate, 1–2 times as long as the sepals; pollen 3-porate, triangular in polar view |
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The name
Brazil. Roraima, Sema Ecological Station, Ilha de Maracá,
Shrub or small tree to 7 m tall. Branches terete, glabrous, brown with grayish lineate lenticels. Leaves trifoliolate; petioles flattened-canaliculate adaxially, 1.6–4.5 cm long, minutely puberulent; leaflets elliptic, 6–10.8 × 1.3–3.4 cm (the lateral ones smaller), chartaceous, the base cuneate on distal leaflets, obtuse-acute and asymmetrical on lateral ones, the apex acute to acuminate, the margins serrate. Flowers axillary, solitary or in short (1–2 cm long), axillary racemes; pedicels 8–10 mm long; sepals 4, concave, obovate, rounded at apex, puberulent, ca. 2 mm long; disc cupular, glabrous, with sub-fimbriate margin; filaments glabrous, 4–5 mm long; pistillode ca. 0.4 mm long; pistillate flowers unknown. Monocarps ellipsoid, divaricate, glabrous, 1–1.2 cm long; exocarp red, fleshy and thin; endocarp subwoody. Seed obovoid, ca. 1 cm long, with papery testa.
Pollen grains in
Pollen of
Known only from Brazil (Roraima) and Guyana, on terra firme forest.
Guyana
The above cited collections by
I thank Bobbi Angell for the great botanical illustration of the new species, Mark T. Strong for preparing the SEM samples and pictures, and for proofreading the manuscript, Ken Wurdack for locating additional collections at NY, Genise Somner and Douglas Daly for their helpful comments, and the curators of BM, K, NY, & W for making their collections available for this study.