Rhodolaena macrocarpa G.E. Schatz, Lowry & A.-E. Wolf

Schatz, George E., Lowry Ii, Porter P. & Wolf, Anne-Elizabeth, 2000, Endemic families of Madagascar. VI. A synoptic revision of Rhodolaena (Sarcolaenaceae), Adansonia (3) 22 (2), pp. 239-252 : 248-251

7. Rhodolaena macrocarpa G.E. Schatz, Lowry & A.-E. Wolf , sp. nov.

Haec species a congeneris foliorum venatione secundaria divergente, floribus solitariis atque fructum magni valvis 2-3.3 × 2-2.5 cm distinguitur.

TYPUS. — Andrianjafy, Rabenantoandro, Razafindrakoto, Birkinshaw & Lowry 61, Madagascar, Prov. Antsiranana, massif de Tsihomanaomby, ca. 35 km au Nord de Sambava , W d’Ambavala , forêt dense sur pente, sur sable quartzite, 14°06’03”S, 50°02’52”E, 150 m, 7 May 2000, fr. (holo-, MO!; iso-, K!, P!, TAN!, TEF!) .

Tree to 10 m tall, branches glabrous. Leaves with petiole 0.7-1.6 cm long, canaliculate, glabrous; lamina stiff coriaceous, drying olive green, glossy, narrowly elliptic to elliptic to slightly obovate-elliptic, 3.2-11.2 × 2-6.8 cm, base acute to cuneate and slightly asymmetrical, apex abruptly short acuminate, occasionally rounded, margin weakly to strongly revolute, venation brochidodromous with 9-11 secondary veins per side strongly ascending at 45º angle or less, the secondary veins only slightly raised on upper surface; flowers known only at post-anthesis; peduncles in fruit 4.5-7.5 cm long, 2 mm in diam.; involucre entire, shallowly 3-lobed, lobes

3 mm long, 5 mm broad, densely light olive-tan stellate pubescent; pedicel post-anthesis 3-4 mm long, 2-3 mm in diam., expanding in fruit to 5-7 mm long, 4 mm in diam.; outer 2 sepals triangular to ovate, 1-2 × 0.6-2 mm, inner 3 sepals broadly elliptic, 2.2-2.7 × 1.3-1.8 cm; stamens ca. 60, filament 4.5-6 cm long, anther 0.7 mm long; style 6.5 cm long, stigma capitate with

3 triangular lobes; fruits globose, 1.5-1.7 cm in diam., weakly 3-sided in cross section, valves of dehisced fruits ovate, 2-3.3 cm long, 2-2.5 cm broad, densely stellate-strigose, with the central trichome branch much longer than the others.— Fig. 2 .

Rhodolaena macrocarpa is a medium-sized tree that occurs in low elevation humid forest, and is known only from the type locality N of Sambava ( Fig. 4 ). It is distinguished by its stiff coriaceous leaves drying glossy olive green with secondary veins strongly ascending at a 45º angle or less to the midvein, and its large fruit, exceeding those of all other members of the genus. Based on the available material, R. macrocarpa appears to be the only member of the genus with flowers borne singly above the involucre, whereas in the other species they consistently occur in pairs, one of which develops into fruit and the other aborts, leaving a more or less evident scar.

VERNACULAR NAME.— Voandrozana.

PARATYPES. — MADAGASCAR, Prov. Antsiranana: Service Forestier (Capuron) 27200, Madagascar, Prov. Antsiranana, entre Andrangana et la rivière Anjambazamba (route de Sambava à Antsirabe-Nord ), [14°05’S, 50°03’E], 2-7 Dec. 1966, fr. ( K, MO, P, TEF).

Figures

Fig. 2. — Rhodolaena coriacea: A, flowering branch; B, leaf (adaxial surface); C, leaf (abaxial surface); D, flower (schematic view); E, sepals (inner, outer). — Rhodolaena macrocarpa: F, fruiting branch; G, leaf (adaxial surface); H, leaf (abaxial surface); J, dehisced fruit with involucre (A, Service Forestier 8893; B-E, Service Forestier 8864; F, Andrianjafy et al. 61; G-J, Service Forestier 27200).

Fig. 4. — Distributions of Rhodolaena, mapped on the bioclimatic zones of Madagascar (after CORNET 1974; see SCHATZ 2000). R. humblotii (•), R. macrocarpa (*).