Andrachne gracilipes 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 : 126-129

Andrachne gracilipes Petra Hoffm. , sp. nov.

Species A. ovali similis sed petiolis pedicellis femineisque longioribus sepalis femineis majoribus fructibus minoribus stylis longioribus differt.

TYPUS. — Chauvet 372, Madagascar, prov. Tuléar [ Toliara ], Gorges du Fiherenana, 18 Nov. 1962 (holo-, P!; iso-, TEF).

Apparently dioecious shrub 2- 3 m. Young twigs flattened or terete, striate, light brown, glabrous. Leaves ovate, apically acute to rounded, often mucronate, basally acute to rounded, very shortly decurrent, 2.5-6 cm long, 1-2.7 cm wide, 1.5-3.1 times longer than wide, glabrous or with a few hairs along the midvein abaxially, membranaceous, dull, drying olive-green, concolourous or slightly paler abaxially, midvein slightly raised to slightly impressed adaxially, secondary veins 3-7 pairs, tertiary and finer venation lax, reticulate. Petiole 7-13 mm long, 0.3-0.5 mm wide, deeply and narrowly channelled adaxially, glabrous or with a few hairs. Stipules persistent, ovate, apically obtuse to rounded, 1.5-2 mm long, ca. 1 mm wide, glabrous, margin hyaline, fimbriate.

Staminate flowers not known. Pistillate flowers solitary, ca. 3 mm long, ca. 6 mm wide. Bracts 3(-4?) per flower, ovate, 1.5-2 mm long, 0.7- 1 mm wide, glabrous, margin hyaline. Pedicel terete, 15 mm long, 0.3 mm wide at the base, 0.6 mm wide at the apex, glabrous, articulate just above the base (articulation practically invisible before abscission). Sepals 5, sometimes unequal, spathulate, rounded to obtuse, 3-4 mm long, 2.5- 3 mm wide, slightly accrescent (up to 5 × 4 mm, becoming elliptic to orbiculate), spreading up to fruit maturity, glabrous, margin narrowly hyaline, slightly erose and with scattered hairs. Petals spathulate, apically rounded, hardly exserted from the disc, 0.5-1 mm long, 0.3-0.5 mm wide, membranaceous, glabrous, margin finely erose, with a few hairs. Disc annular, 0.4 mm long, membranaceous to chartaceous, glabrous, margin finely erose; at fruit maturity tearing between the sepals, then appearing antisepalously lobed or divided. Ovary ovoid to globose, densely whitish pubescent. Styles erect, bipartite to the base, the branches terete, 1-1.5 mm long, hardly tapering towards the apex, glabrous. Obturator with a suture between the ovules.

Fruits depressed globose, ca. 4 mm long, 5- 6 mm wide, olive-green when dry, pubescent, 3- lobed, the lobes more or less rounded, without or with very faint dorsal ridges along each lobe; dehiscence of septa apparently irregular but difficult to establish as septa are extremely thin and brittle. Fruiting pedicel (15-)20-50 mm long, 0.5-0.6 mm wide at the base, 1-1.2 mm wide at the apex. Columella ca. 6 times longer than the narrowest width, 4 mm long, 0.7 mm wide in the middle, base thickened to 2 mm, apex thickened to 1.2-1.5 mm. Exo- and mesocarp together ca. 0.2 mm thick when dry, reticulate on inner surface. Endocarp ca. 0.4 mm thick, brownish yellow. Seeds 3.5-4 mm long, 2.5-3 mm wide, very dark brown, rugose, with 6-7 sharply defined, slightly sinuous folds running at right angles from the raphe to the dorsal part of the seed, some of them branching, resulting in 10-12 anastomosing folds running across the dorsal part, folds 2-3 times narrower than the flat ridges between them, extending on the inside of the seed-coat ca. 0.7 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 × 1.5 mm; radicle 1.8 mm long, 0.4 mm in diameter. — Fig. 2.

ETYMOLOGY. — The epithet refers to the slenderness and length of the petiole and pedicel of this species.

D ISTRIBUTION. — Madagascar, Toliara province, around the Analavelona massif and the Fiherenana river. — Fig. 3.

ECOLOGY. — Dry deciduous forest, over basalt and sandstone. As Madame CHAUVET almost certainly collected the type at 250-300 m altitude (J. BOSSER, pers. comment), this species ranges between ca. 250 and 1250 m altitude. Subarid bioclimatic zone of CORNET (1974).

V ERNACULAR NAMES AND USES. — None recorded.

PARATYPES. — MADAGASCAR, Toliara province: Humbert 14232, Forêt d’Analavelona au N du Fiherenana , sur basalte et grès, 950- 1250 m, Mar. 1934 (P!); Humbert 19739, Forêt d’Analavelona (bassin du Fiherenana), forêt tropophile sur basalte, 1000-1200 m, 15-19 Dec. 1946 ( P!) .

Figures

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