79. Guatteria heteropetala Benth. — Plate 4c, f; Map 17

Guatteria heteropetala Benth.(1843) 360; R.E.Fr. (1939) 538; Erkens & Maas (2008) 405. — Heteropetalum brasiliense Benth. (1860) 69; R. E.Fr. (1930) 74, t. 2. —

Type: R.H. Schomburgk 1 950 (holo K; iso B, BM 2 sheets, F, G 2 sheets, K, L, P, U), Brazil, Amazonas, Rio Negro, anno 1839.

Heteropetalum spruceanum R.E.Fr. (1930) 75, t. 3. — Type: Spruce 3184 (holo B; iso BM, BP, C, E, G 3 sheets, K, MG, NY, P), Venezuela, Bolívar, Río Pasíba (‘Vasiva’), affluent of Río Casiquiare, Dec. 1853.

Heteropetalum spruceanum R.E.Fr. var. longipetalum R.E.Fr. (1957a) 330. — Type: Maguire et al. 36261 (holo NY; iso S), Colombia, Guainía, Río Atabapo, between San Fernando de Atabapo and Cacagual, 18 Nov.1953.

Tree 3–6 m tall, to c. 4 cm diam, sometimes several-stemmed (O. Huber & Medina 5818), young twigs sparsely covered with appressed hairs, very soon glabrous. Leaves: petiole 8–22 mm long, 1–3 mm diam; lamina narrowly elliptic to narrowly oblong-elliptic, 6–18 by 2–6.5 cm (leaf index 2–4.7), coriaceous, not verruculose, dull, greyish or brownish green above, brown or brownish green below, glabrous above, sparsely covered with appressed hairs to glabrous below, base attenuate, apex acute, acuminate (acumen 5–15 mm long) or obtuse, primary vein impressed, flat, or more or less raised above, secondary veins distinct, 11–15 on either side of primary vein, slightly raised above, smallest distance between loops and margin 1–2.5 mm, tertiary veins raised above, reticulate. Flowers in 1(–2)-flowered inflorescences in axils of leaves, sometimes accompanied by lateral shoot from axial bud; pedicels 5–10 mm long, 1.5–2 mm diam, fruiting pedicels to c. 15 mm long, c. 2.5 mm diam, rather densely to sparsely covered with appressed hairs, articulated at 0.2–0.4 from the base, bracts 5–6, soon falling, the 2 uppermost still present at flowering time, broadly elliptic, c. 2 mm long at the base to 6 mm long at the top; flower buds conical; sepals free, broadly ovate to broadly ovate-triangular, acuminate, 6–7 by 5–6 mm, appressed, outer side densely covered with appressed hairs; petals yellow or reddish yellow in vivo, strongly unequal, narrowly ovate to ovate, outer ones 7–12 by c. 4 mm, outer side densely covered with appressed hairs, inner ones 13–32 by 8–13 mm, outer side densely to rather densely covered with appressed hairs; stamens c. 1.5 mm long, connective shield papillate. Monocarps 2–13, reddish to reddish violet in vivo, black to brown in sicco, ellipsoid to narrowly ellipsoid, 12– 22 by 6–12 mm, smooth or somewhat longitudinally ridged, sparsely covered with appressed hairs, soon glabrous, apex rounded to slightly hard-pointed, wall 0.2–0.5 mm thick, stipes 0–2 by 0–2 mm. Seed ellipsoid, 13–18 by 6–7 mm, pale brown, pitted to transversely grooved, raphe not distinct from rest of seed.

Distribution — Amazonian Colombia (Guainía), Venezuela (Amazonas), Brazil (Amazonas).

Habitat & Ecology — In periodically inundated, black water-flooded igapó forest. At elevations of up to 125 m. Flowering: March, July to December; fruiting: January, February, May.

Vernacular names — Venezuela: Majagua (Maguire et al. 36261, Velazco 1883), Palo de boya negro (O. Huber & Medina 5818).

Note — Guatteria heteropetala is one of the few species in the genus occurring in periodically inundated forests. It is easily recognizable by strongly unequal petals, the inner ones being almost twice as long as the outer ones. This was the main reason why this taxon was placed by earlier authors in the segregate genus Heteropetalum. Recent research (Erkens et al. 2009) proved, however, that it should better be merged into Guatteria.