Olax capuronii, Rogers & Malécot & Sikes, 2006

Rogers, Zachary S., Malécot, Valéry & Sikes, Kendra G., 2006, A synoptic revision of Olax L. (Olacaceae) in Madagascar and the Comoro Islands, Adansonia (3) 28 (1), pp. 71-100 : 77-79

2. Olax capuronii

Z.S.Rogers, Malécot & Sikes, sp. nov. ( Fig. 2 )

“ Olax suarezensis ” Capuron, Olacacées, Opiliacées et Santalacées arbustives ou arborescentes de Madagascar: 18 (1968), nomen inval. [ineffective publication].

Olax capuronii e O. madagascariensi in laminis obovatis raro ellipticis vel ovatis 1-4.2 cm longis (haud ovatis, raro ellipticis vel obovatis, 4.5-11.5 cm long), nervatura adaxiali inconspicua (haud utrinque vulgo manifesta), apicibus rotundatis obtusis vel raro acutis (haud acuminatis raro acutis), et fructibus obovoideis (haud sphaeroideis), differt.

TYPUS. — Madagascar. Prov. Antsiranana, Orangéa, à l’Est de Diégo-Suarez , [12°15’S, 49°23’E], 24.III.1964, fl., imm. fr., Service Forestier (Capuron) 23275 (holo-, P!, iso-, P-00418013!, TEF!) .

PARATYPES. — Madagascar. Prov. Antsiranana, Baie des dunes, 12°14’26”S, 49°22’17”E, 2 m, 18.V.2004, imm. fr., Andrianjafy et al. 427 (MO!, P, TAN, WAG!) . — Diégo- Suarez, Vovo Village District , 12°19’05”S, 49°23’07”E, 85 m, 22.IV.1993, fl., Harder et al. 1682 (MO!, P!). — Forêt d’Analabe, Fivondronana Vohémar, Firaisana Nosy be, Fokontany Anjiabe, 13°04’50”S, 49°54’07”E, 11.VII.2003, imm. fr., Rabehevitra et al. 260 (K!, MO!, P, TEF). — Forêt de l’Orangéa, Fivondronana Antsiranana I, Firaisana Ramena , 12°14’20”S, 49°21’49”E, 13 m, 29.VIII.2001, imm. fr., Rabenantoandro & Razanatsoa 576 (MO!, P, TAN) . — Same locality, 18.X.1954, fr., SF (Capuron) 11333 (P!, TEF!) . — Same locality, 9.XI.1961, imm. fr., fr., SF (Capuron) 20372 (P[2]!, TEF!) . — Same locality, 1.II.1969, fl., fr., SF (Capuron) 28742 (P!, TEF!) .

DESCRIPTION

Trees to 4 m tall. Branches glabrous; young branches 4-sided, winged; older branches terete, darker; bark cracked, exfoliating. Leaves alternate, distichous, obovate, rarely elliptic or ovate, 1-4.2 cm long, 6- 21 mm wide, c. 1.5-2 times longer than wide; leaf blades coriaceous, glabrous, strongly wrinkled and dark green adaxially, smooth or slightly wrinkled and lighter green abaxially, base obtuse or rarely acute (strongly decurrent with petiole), margin revolute, apex obtuse, broadly rounded, rarely acute or emarginate, often with an abaxially decurved apicule; midrib depressed adaxially, raised abaxially, glabrous; venation inconspicuous or adaxially represented by 2-4 faint pairs of depressed secondaries, abaxially inconspicuous or faintly visible; petioles 0-0.5 mm long, c. 1 mm in diam., glabrous. Inflorescences racemose; axes 4-sided, c. 0.8 mm in diam., reaching 1.1 cm long, proliferating with up to 9 flowers; floral pedicel 1.9-3 mm long, c. 0.5 mm in diam. Flowers hermaphroditic, tubular, heterostylous; calyx cupuliform, green, 0.3-0.5 mm long, glabrous, margin wavy, semimembranous; petals 3, white, oblong, 6.5-8 mm long; petal lobes ovate, 2.5-3 mm long, 1.5-2 mm wide; petal ligule 0-0.1 mm long, sparsely puberulent, with a few much longer (c. 0.5 mm long), irregularly spaced trichomes; free portion of filaments 0.5-1.5 mm long; fertile stamens 3; anthers oblong, c. 1.5 × 0.8 mm, longitudinally dehiscent; staminodes 6, each bifid portion narrowly elliptic, c. 2 × 0.5 mm, membranous, glabrous, base thick, dark, articulate at filament; nectary disc annular, c. 0.1 mm tall, glabrous; ovary ovoid, c. 2 × 1 mm; style c. 0.3 mm in diam., articulate above ovary in immature fruit; long style 4-5 mm long; short style c. 1.5 mm long; stigma capitate, 3-lobed, c. 0.3 mm in diam., papillate. Drupes obovoid, slightly depressed at apex, 1.9-2.2 cm long, 1.6-1.8 cm in diam.; calyx in fruit not accrescent, circular, c. 3 mm in diam., margin entire; stylar remnants c. 0.2 mm long.

REMARKS

Olax capuronii has flowers with 3 petals, 3 stamens, 6 staminodes, and a non-accrescent calyx in fruit. This combination of characters suggests an affinity with O. madagascariensis , but O. capuronii differs from that species by its 1-4.2 cm long, obovate, rarely elliptic or ovate leaves (vs. 4.5-11.5 cm long, ovate, rarely elliptic or obovate, leaves), inconspicuous or only faintly visible adaxial venation (vs. venation usually visible on both surfaces), rounded, obtuse, or rarely acute or emarginate leaf apex (vs. acuminate or rarely acute apex), and obovoid (vs. spheroid) fruit. When sterile, O. capuronii should not be confused with O. antsiranensis , a species with leaves of similar size and sometimes shape, because leaf blades of the former are more coriaceous, more distinctly veined, and have more strongly revolute margins.

This species was not treated by Cavaco & Keraudren (1955a) in the Flore as collections were not yet available. We concur with Capuron (1968), who intended to describe it as a new species, and therefore would like to honor him with our choice of epithet.

DISTRIBUTION AND PHENOLOGY

Olax capuronii is endemic to three sandy littoral forest fragments (Orangéa, Vovo, Vohémar) in

northern Madagascar from 0 to 85 m elevation (Fig. 9). The species has been recorded in flower from February to April and in fruit in May, July to August, and October through November.

VERNACULAR NAME

Hazomena (Andrianjafy et al. 427).

CONSERVATION STATUS

Olax capuronii has not been collected inside any formally protected areas. The EOO for the species is 212 km 2 and the AOO is 400 km 2 (grid cell size 10 × 10 km). These figures indicate that O. capuronii should be considered Endangered (EN B1ab + B2 ab).

Figures

FIG. 2. — Olax capuronii Z.S.Rogers, Malécot & Sikes: A, branch; B, flower (one petal, one stamen, and two staminodes removed); C, fruit. A, C, Service Forestier 20372; B, Service Forestier 23275 (type). Scale bars: A, 1 cm; B, 2 mm; C, 5 mm.