Brexia arborea H. Perrier

Schatz, George E. & Lowry Ii, Porter P., 2004, A synoptic revision of Brexia (Celastraceae) in Madagascar, Adansonia (3) 26 (1), pp. 67-81 : 73-75

3. Brexia arborea H. Perrier

Bull. Soc. Bot. France 80: 203 (1933). — Lectotype (here designated): Perrier de la Bâthie 16000 (Leg. Ursch), Madagascar, Prov. Toamasina, Est, Analamazoatra, rive gauche de la Vohitra, bud, fl. (P!; iso-, K!, MO!, P!, TAN!).

Brexia arborea is assumed to be a cauliflorous medium-sized tree, known only from humid forest at Analamazaotra-Périnet RS (Fig. 2), where it inexplicably has not been collected since 1924. It can be recognized by its leaves with entire margins, and flowers and fruits that are the largest in the genus.

Among the original syntypes designated by PERRIER DE LA BÂTHIE (1933), one of the 3 duplicates in the Paris herbarium of Perrier de la Bâthie 16000 carries a “Type” sticker (undoubtedly affixed after the species was described), and is here chosen as the lectoype.

CONSERVATION STATUS. — Although Brexia arborea has not been collected since 1924, and therefore in theory has an EO of less than 100 km 2, an AO of perhaps no more than 10 km 2, and is known from only a single locality, the projected habitat stability in the effectively protected Analamazaotra-Périnet RS suggests an assessment of Vulnerable (VU D2).

MATERIAL EXAMINED. — MADAGASCAR: D’Alleizette 1480, Analamazaotra-Périnet RS; Humbert 2261 , Analamazaotra-Périnet RS; Perrier de la Bâthie 16000, Analamazaotra-Périnet RS.

4. Brexia australis G.E. Schatz & Lowry , sp. nov.

Haec species a congeneris foliis subsessilibus margine spinoso atque inflorescentia pseudoumbellata flores geminatos vel solitarios gerente pedunculo 3-17 mm longo insidente distinguitur.

FIG. 2. — Distributions of Brexia , mapped on the bioclimatic zones of Madagascar (after CORNET 1974; see SCHATZ 2000).

TYPUS. — McPherson, Dumetz & Rabevohitra 14118, Madagascar, Prov. Toliara, forest of Petriky, region of Fort Dauphin , 25°05’S, 46°52’E, 25 m, 16 Oct. 1989, fl. (holo-, MO!; iso-, P!, TAN!) .

Shrub to tree 2-5 m tall. Leaves 1.8-12 × 1.4- 4.5 cm, elliptic to occasionally obovate (juvenile leaves to 21 × 6.6 cm, oblanceolate to oblong), glabrous above and below, glossy above, midrib flat to slightly raised above, prominently raised below, secondary venation weakly brochidodromous with 6-9 secondary veins per side, the base obtuse to rounded, the margin spinose, the spines unequal, some less than 0.1 mm, others to 3 mm, the apex rounded. Petioles often subsessile, occasionally 1-3(-7) mm long (5-21 mm on juvenile leaves), 2 mm in diam., terete, glabrous. Inflorescences axillary, a 2-flowered pseudoumbel, or sometimes reduced to a single flower, subtended by a minute bracteole, the peduncle 3-17 mm long, the pedicels 4-10 mm long, 1 mm in diam., to 7 mm and 2 mm in diam. in fruit, subtended by a minute bracteole. Sepals connate for 3 mm at their base, 5 × 5 mm, broadly ovate, glabrous, the margin entire, the apex rounded. Petals 10-12 × 7-10 mm, oblong, glabrous, membranous with evident venation, the base truncate, the margin entire, the apex obtuse. Disk 5-lobed, the lobes free, 6 × 4-7 mm, membranous, glabrous, the margin irregularly shallowly to deeply 4-8-laciniate. Stamens fused to the disk at their base, 17 mm long; filaments 12 mm long, flattened, 1.2 mm broad at their base; anthers 5 × 2.5 mm, lanceolate, dorsifixed. Ovary 10 mm tall, 3.5 mm in diam. at the base, ovoid, 10-ribbed, crowned at the apex with 5-lobed stigma, the lobes folded inward. Fruit 2.7-4.0 cm long, 1.3-1.6 cm in diam., ellipsoid to oblong, 5-angled-winged, the wings to 1 mm, the apex acuminate to apiculate, to 4 mm long, woody. Seeds 5-7 mm long, 3-5 mm in diam., ellipsoid. — Fig. 3 .

Brexia australis is known from extreme southern Madagascar in humid to subarid forest on sand from west of Fort Dauphin at Petriky to west of Cap Sainte Marie (Fig. 2). It can be distinguished by its subsessile leaves with spinose margins, and inflorescences of paired or sometimes solitary flowers borne on a short peduncle 3-17 mm long.

CONSERVATION STATUS. — With an EO of less than c. 800 km 2, an AO of perhaps 400 km 2, and only 3 subpopulations, none of which are encompassed within the protected areas network, Brexia australis is assigned a preliminary status of Endangered (EN B1ab2ab).

PARATYPES. — MADAGASCAR. Prov. Toliara: Descoings 2583, environs de Manambaro, W de Fort Dauphin , [25°09’S, 46°45’30”E], 21 Feb. 1957, fl .

(TAN); Dumetz, Gereau & Rabevohitra 650, Petriky, 15 km WSW of Fort Dauphin, 25°04’S, 46°51’E, 0- 10 m, 11 Apr. 1989, fr. (MO, P, TAN); Gereau, Schatz & Dumetz 3224, same locality, 9 Mar. 1989, fl., fr. (MO, P, TAN, TEF); Humbert & Capuron 28992, Baie des Galions (Ranofotsy) au SW de Fort Dauphin, [25°09’S, 46°43’E], 1-100 m, 18-21 Feb. 1955, fl. (P); Humbert & Capuron 28995, same locality, fr. (P); Humbert & Capuron 29321, falaise côtière NW du Cap Sainte Marie, vers Lavanono, [25°28’S, 45°00’E], 1-150 m, 8 Mar. 1955, fl. (P); Miller & Randrianasolo 6204, 5 km S of Manambaro, 23 km W of Fort Dauphin, 25°05’S, 46°49’E, 150 m, 29 Mar. 1991, fl., fr. (MO, P); Rabevohitra 2119, Petriky, 15 km WSW of Fort Dauphin, 25°04’S, 46°52’E, 10 m, 12 Jan. 1990, bud, fr. (MO, P, TAN, TEF); Randriantafika et al. 77, forêt littorale sur sable de Petriky, Ambovo, Manambaro, Fort Dauphin, 25°03’39”S, 46°52’09”E, 10 m, 17 June 1999, fl. (MO, P, TAN).

Figures

FIG. 3. — Brexia australis: A, adult leaves; B, adult leaf showing detail of venation; C, flower; D, flower (exploded diagram); E, petaloid disc segment (enlarged); F, fruit. A-D, McPherson 14118; F, Miller 6204.