Andrachne cerebroides Petra Hoffm., 2000

Hoffmann, Petra, 2000, Revision of Andrachne sect. Pseudophyllanthus (Euphorbiaceae), with the description of two new species from Madagascar, Adansonia (3) 22 (1), pp. 123-133 : 125-126

Andrachne cerebroides Petra Hoffm. , sp. nov.

Species A. ovali similis sed foliis majoribus longe acuminatis petiolis pedicellis femineisque longioribus robustisque sepalis femineis majoribus differt.

TYPUS. — SF (Capuron) 23576, Madagascar, prov. Fianarantsoa, Est, au Sud de Farafangana (route de Manombo , aux P.K. 13-17), restes de forêt, sur latérites de basalte, 11 Oct. 1964 (holo-, P!; iso-, K!, TEF!) .

Apparently dioecious shrub 2.5 m. Young twigs flattened, green, glabrous. Leaves ovate, apically long acuminate, hardly mucronate, basally obtuse to rounded, shortly decurrent, 3.5- 8.5 cm long, 1.5-7 cm wide, 1.5-2.8 times longer than wide, glabrous, thinly chartaceous, moderately shiny, drying olive-green, concolourous, midvein slightly raised to slightly impressed adaxially, secondary veins 4-6 pairs, tertiary and finer venation hardly prominent, lax, reticulate. Petiole 4-12 mm long, 0.5-1 mm wide, channelled adaxially, glabrous or with a few hairs. Stipules persistent, deltoid, apically acute to acuminate, 1-1.5 mm long, 0.7-1 mm wide, glabrous or sparsely hairy, margin hyaline, fimbriate.

Staminate inflorescence axes up to 5 mm long, rarely branched once, curled, with numerous (up to 40 per inflorescence) pedicel stumps ca. 0.2 mm long (“podia” in WEBSTER 1965: 325) arranged distichously and in pairs ( Fig. 1N ). Bracts 2 per flower, deltoid, unequal, larger on the outside than within each pair of flowers, 0.5- 0.8 mm long, 0.2-0.5 mm wide, pubescent abaxially, glabrous adaxially, margins fimbriate. Buds globose, slightly depressed apically. Staminate flowers (1-)2-3 per inflorescence, 2 mm long, 3 mm wide. Pedicel filiform, 3-5 mm long, 0.2- 0.4 mm wide, glabrous, articulate just above the base (articulation practically invisible before abscission, leaving a “podium” ( WEBSTER 1965: 325) after abscission). Sepals 5, more or less orbicular, 1.5-2 mm long, 1.5-2 mm wide, sparsely pilose abaxially, glabrous adaxially, margin entire, hyaline, sparsely fimbriate. Petals 5, oblong to spathulate, apically rounded, basally shortly clawed, 0.8-1.2 mm long, 0.5-0.8 mm wide, glabrous, margin erose. Disc 1.5 mm in diameter, antisepalously lobed, glabrous; lobes 0.5 mm long, emarginate, no sutures visible. Androecium 1 mm long, 1 mm wide, glabrous; stamens 5, antisepalous; filaments terete, fused at the base for ca. 1/2 of their length, bent downwards apically; anthers 0.5 mm long, 0.6-0.8 mm wide, deeply 4-lobed. Pistillode obconical, 3- lobed apically, 0.3 mm long, 0.2 mm wide, pilose.

Pistillate flowers solitary or in twos, 2-3 mm long, 4-6 mm wide. Bracts several per flower, deltoid, ca. 0.5 mm long, ca. 0.5 mm wide, pilose, margin fimbriate. Pedicel terete, 15-25(-55) mm long, 0.3-0.5 mm wide at the base, 0.6-1 mm wide at the apex, glabrous, articulate ca. 1 mm from the base, leaving a “podium” ( WEBSTER 1965: 325) after abscission. Sepals 5, usually unequal, oblong to orbiculate, 2-3 mm long, 2-2.5 mm wide, glabrous, slightly accrescent (up to 4 × 4 mm), spreading at anthesis, reflexed at fruit maturity, margin hardly hyaline, entire. Petals elliptic, spathulate or orbiculate, apically rounded, 0.5- 1(-2) mm long, 0.3-0.7(-1.5) mm wide, membranaceous, glabrous, margin slightly erose, sometimes absent, small and large petals in the same flower. Disc annular, often antipetalously lobed, lobes apically emarginate, 0.4-0.5 mm long, more or less fleshy, glabrous, margin slightly erose or entire, tearing irregularly at fruit maturity. Ovary globose to nearly cylindrical, densely whitish appressed-pubescent. Styles horizontally spreading, bipartite to the base, the branches terete, 0.5-1 mm long, hardly tapering towards the apex, glabrous. Obturator without suture between ovules.

Fruits olive-green when dry, pubescent; dehiscence of septa in only one line running roughly parallel to the pericarp, this line erose and irregular as septa are very thin and brittle. Fruiting pedicel 22-55 mm long, 0.5 mm wide at the base, 1.5 mm wide at the apex. Columella ca. 5 times longer than the narrowest width, 3.5-4 mm long, 0.7-0.8 mm wide in the middle, base thickened to 1.2 mm, apex thickened to 1 mm. Exo- and mesocarp together ca. 0.2 mm thick when dry, rough on inner surface. Endocarp ca. 0.5 mm thick, brownish yellow. Seeds 3.5-4 mm long, 2.5-3 mm wide, medium brown, with ca. 8 vaguely defined, slightly sinuous folds running at right angles from the raphe to the dorsal part of the seed, some of them branching, resulting in 15- 18 anastomosing folds running across the dorsal part, folds 2-3 times narrower than the flat ridges between them, in some places fading into a shallow irregularly foveolate-rugulose pattern, extending on the inside of the seed-coat up to 0.3 mm deep into the endosperm, raphe only slightly impressed, extending ca. 0.2 mm deep into the endosperm. Cotyledons oblong, apically nearly truncate, 2.5 × 1.8 mm; radicle 1.5 mm long, 0.5 mm in diameter. — Fig. 1.

ETYMOLOGY. — The epithet refers to the brain-like sculpture of the seed.

DISTRIBUTION. — Madagascar, Fianarantsoa province, around Farafangana and Manombo.— Fig. 3.

ECOLOGY. — Evergreen wet lowland forest, on laterite derived from basalt. Humid bioclimatic zone of CORNET (1974).

V ERNACULAR NAMES AND USES. — None recorded.

PARATYPES. — MADAGASCAR, Fianarantsoa province: Bosser 18539, Farafangana , vestige de forêt de basse altitude, Dec. 1963 ( P!) ; Bosser 18600, 15 km de Farafangana, forêt de basse altitude, Dec. 1963 ( P!) ; SF (Capuron) 23592, au Sud de Farafangana (route de Manombo , au P.K.18,5), restes de forêt, sur latérites de basalte, 14-17 Oct. 1964 ( P!, TEF!) .

Figures

Fig. 1.— Andrachne cerebroides: A, habit with columellae; B, mericarp of fruit after dehiscence; C, columella with persistent disc, petals and sepals; D, seed, lateral view; E, embryo, lateral view; F, young fruit; G, seed, dorsal view; H, pistillate flower, showing “podium” at base of pedicel; I, disc and petals of pistillate flower; J, pistillate flower, sepals removed; K, disc and petals of staminate flower; L, staminate flower; M, androecium; N, staminate inflorescence showing “podia” left after abscission and two buds. A-J, drawn from SF (Capuron) 23576; K-M, drawn from Capuron 23592; N, drawn from Bosser 18539.

Fig. 3. — Geographic distribution of Andrachne cerebroides (triangles) and Andrachne gracilipes (circle).