Description

Trees: branches basitonic?, in axils of cataphylls; twigs terete, ca. 2 mm diam.; epidermis brownish; terminal bud slender, ca. 3 X 2 mm; cataphylls caducous; indument pubescent, persisting for at least two flushes, the hairs dense, up to 0.5 mm long, straight, erect, yellowish. Leaves: petioles pulvinate, 0.5–0.8 cm X 1.5–2.5 mm, terete; blades thinly chartaceous, flat to bullate, broadly elliptic, 7–15 X 3–7 cm; base acute to obtuse, 70–100°; apex obtuse to acute, 70–100°, ultimately acuminate for up to 1.5 cm; margin plane; primary vein above and below raised; secondary veins 6–8 pairs, equidistant, brochidodromous, above and below raised, diverging at 55–65°, evenly arching, chordal angle ca. 30°, the angle uniform along blade length; tertiary veins above impressed, below raised, random-reticulate; higher order veins above inconspicuous, below slightly raised; surface above dull dark green, below shiny light green; indument above absent, the primary vein tomentose, below minutely puberulous, the hairs isolated, up to 0.2 mm long, straight, erect, yellowish, denser on the veins, caducous after one flush. Staminate inflorescences: basitonic, pendulous, peduncles up to 5 cm long, the hypopodia ca. 3 cm X ca. 0.4 mm, branch orders 3, the second-order branches ca. 5, dispersed, lowest branch up to 0.5 cm long, color and indument of all axes as on twigs; bracts and bracteoles caducous (not seen). Staminate flowers: pedicels ca. 2.4 X 0.6 mm, the diameter even throughout; receptacle flat, ca. 0.8 X 2 mm; tepals membranaceous, elliptic, ca. 2.5 X 1.2 mm, at anthesis spreading, reddish, somewhat translucent, adaxially glabrous; stamens of whorls I and II spathulate, the anthers reniform, ca. 0.8 X 0.6 mm, glabrous, the locelli 4, apical, in a strong arch, introrse, the glands absent; whorl III columnar, ca. 1.2 X 0.8 mm, glabrous, the locelli 4, the upper pair latrorse, the lower pair extrorse, the glands fused, forming a continuous ring; whorl IV absent; all stamens yellowish; pistillode absent. Pistillate flowers: pistil ca. 2.5 X 1.5 mm; ovary globose, ca. 1.5 mm long, glabrous. Fruits unknown.

Field notes

Shrubs up to 3 m tall and 3 cm diam. Tepals pink to red.

Distribution (Figure 11)

Upper Jari river on the Tumucumaque mountain range on the Brazil/French Guiana border, at 380–670 m elev.; a specimen from Mt. St. Marcel (500 m elev.) in southern French Guiana, may also belong to this species.  An understorey rain forest species of well-drained soils on granitic outcrops.  Flowers in August, at the beginning of the dry season.

Additional specimens examined

French Guiana: Mont St. Marcel, 26 Mar 1976 (pist. fl), Sastre 4551 (CAY, P n.v.).

Brazil. Amapá: Upper Rio Jari, 20 Aug 1993 (pist. fl), de Granville et al. 12383 (CAY n.v., K n.v., MO, NY n.v., U n.v., US); 25 Aug 1993 (stam. fl), de Granville et al. 12457 (CAY n.v., MO, US).

Discussion

Rhodostemonodaphne tumucumaquensis has bright green-drying, undulate to somewhat bullate leaves.  The four specimens cited here were originally included in the description of R. leptoclada Madriñán.  Unlike R. leptoclada, which has green flowers, the flowers of R. tumucumaquensis are red.  As originally described and illustrated the pistillate individuals of R. tumucumaquensis have their tepals and stamens dehiscing in a ring after anthesis, while in R. leptoclada they are not.  The collection from Mt. St. Marcel (initially though of as intermediate between the two above mentioned species) has flower buds at a very early stage of development; it has reddish tomentose twigs and leaves drying darker than R. leptoclada, and it very likely belongs to R. tumucumaquensis.