Olax mayottensis, 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 : 90-93

7. Olax mayottensis

Z.S.Rogers, Malécot & Sikes, sp. nov. ( Fig. 7 )

Olax mayottensis a O. dissitiflora in laminis 4.2-10 × 1.5-4.5 (haud 2-5 × 1-2) cm chartaceis vel interdum (prope apices ramulorum) membranaceo-chartaceis (haud laminis totis membranaceo-chartaceis vel semisucculentis), petiolis robustis 1-2 (haud c. 0.5) mm in transversis, pedicellis c. 1 (haud 0.3-0.5) mm in transversis quam corollis valde brevioribus (haud longioribus vel raro aequantibus), et fructibus ovoideis (haud ellipsoideis vel sphaeroideis), differt.

TYPUS. — Comoros. Mayotte , Grande Terre , Mamoudzou, Réserve forestière de Majimbini, [12°47’S, 45°13’E], 24.I.2001, fl., fr., Barthelat, M ’ Changama & Sifary 267 (holo-, P!; iso-, G!, K!, MO!) .

PARATYPES. — Comoros. Mayotte, Grande Terre, Mamoudzou, Convalescence, Réserve forestière de Majimbini, [12°47’S, 45°13’E], 30.I.2003, fl., Barthelat et al. 1140 (G, K, MO, P!). — Bois de Banjoni , 1850, fl., imm. fr., Boivin s. n. (P!). — Without precise locality ,

9.V.1999, fl., Mas 150 (P!). — Dapani, [13°00’S, 45°12’E] , 11.I.1996, fr., Pascal 321 (P!). — Mlima Combani, [12°48’S, 45°10’E], 300 m , 17.I.1997, fl., Pascal 862 (B, BR, G, K, MO!, NY, P!, PRE, WAG). — Hachiroungou, [12°43’S, 45°04’E], 500 m , 4.III.1997, fr., Pascal 905 (G!, K, MO!, P!, WAG). — Maningoni, canton de M. Daperé, district de Mayotte , 27.III.1958, fr., SF (Ahamada) 17989 (P!, TEF!) .

DESCRIPTION

Trees to 10 m tall. Branches glabrous; young branches 4-sided, ± winged; older branches terete or subterete, darker; bark cracked, exfoliating. Leaves alternate, distichous, ovate, 4.2-10 cm long, 1.3-4.5 cm wide, c. 2-3 times longer than wide; leaf blades chartaceous, some blades near tips of branches membranous-chartaceous, both surfaces glabrous, darker adaxially, base obtuse to broadly rounded (shortly decurrent with petiole), apex acuminate, tip rounded; midrib depressed adaxially, raised abaxially, glabrous; venation conspicuous on both surfaces, more visible abaxially; secondary veins 5-8 pairs; fine venation densely reticulate, sometimes adaxially inconspicuous; petioles 3-6 mm long, 1- 2 mm in diam., glabrous, concolorous compared to the midrib. Inflorescences racemose; axes weakly 4-sided or subterete, c. 0.8 mm in diam., reaching 1.6(-2.3) cm long, proliferating with up to 12(-16) flowers; bracts early caducous, semi-membranous, c. 0.5 mm long, c. 0.7 mm wide, glabrous; floral pedicel 2.5-3 mm long, c. 1 mm in diam. Flowers hermaphroditic, tubular, heterostylous; calyx cupuliform, 0.5-0.7 mm long, glabrous, margin entire, smooth or slightly wavy, semi-membranous; petals 5, white, oblong, (5.1-) 6-7 mm long; petal lobes ovate or subtriangular, 2.3-3.2 mm long, 0.9-1.7 mm wide; petal ligule c. 0.1 mm long, puberulent, with a few much longer (c. 0.5 mm long), irregularly spaced trichomes; trichomes filamentous and twisted; free portion of filaments 0.8-1.5 mm long; fertile stamens 3; anthers oblong, 0.8-1.5 mm long, 0.6-0.7 mm wide, longitudinally dehiscent; staminodes (4) 5 (6), each bifid portion narrowly elliptic, 1.6-2.1 mm long, 0.5-0.6 mm wide, membranous, glabrous, base thick, dark, articulate with filament; nectary disc annular, 0.2-0.3 mm tall, glabrous; ovary ovoid or spheroid, 1.2-1.5 mm long, 1.2-1.4 mm wide; style c. 0.3 mm in diam. at midpoint (narrower near stigma), weakly articulate above ovary in late anthesis; long style 3.5-4.3 mm long; short style 2- 2.5 mm long; stigma capitate, 3-lobed, 0.3-0.4 mm in diam., papillate. Drupes ovoid, 9-13 mm long, 7-9 mm in diam.; accrescent calyx completely encapsulating fruit, crustaceous and thick, adpressed but not fused to fruit wall, forming a “loose collar” at apex of fruit, leaving a 1.5-2 mm wide aperture; stylar remnants c. 0.2 mm long.

REMARKS

Olax mayottensis differs from O. dissitiflora by its larger leaves (4.2-10 × 1.5-4.5 vs. 2-5 × 1-2 cm), chartaceous blades with only those near the branch tips membranous-chartaceous (vs. all leaves membranous-chartaceous or semi-succulent), robust petioles (1-2 vs. c. 0.5 mm in diam.), robust pedicels (c. 1 vs. 0.3-0.5 mm in diam.) markedly shorter than the corolla (vs. longer or rarely of equal length to the corolla), and by the ovoid (vs. ellipsoid or spheroid) fruits.

Most of the collections of this species have been made in the last 10 years and no one has critically evaluated the Mayotte material of Olax until now. Some specimens of O. mayottensis were previously identified as O. andronensis using the information available in the Flore ( Cavaco & Keraudren 1955a), while others were determined using the older synonym, O. dissitiflora , recognized in Capuron’s (1968) work.

DISTRIBUTION AND PHENOLOGY

Olax mayottensis is endemic to Mayotte from 300 to 500 m elevation (Fig. 9). The species flowers and fruits from January through May.

VERNACULAR NAMES

M’Kidrikidri (Pascal 321); Sary vavalouza (Barthelat et al. 267; Pascal 862, 905).

USE

Wood used in carpentry (SF 17989).

CONSERVATION STATUS

Olax mayottensis has been collected inside Majimbini Forestry Reserve.The EOO for the species is 200 km 2 and the AOO is 36 km 2 (grid cell size 3 × 3 km).

Olax mayottensis is assigned a provisional conservation status of Endangered (EN B1ab + B2ab).

Figures

FIG. 7. — Olax mayottensis Z.S.Rogers, Malécot & Sikes: A, flowering branch; B, flower (two petals, one anther, and two staminodes removed); C, fruit. Barthelat et al. 267 (type). Scale bars: A, 1 cm; B, 2 mm; C, 4 mm.