Mediusella bernieri (Baill.) Hutchinson

Hong-Wa, Cynthia, 2009, Endemic families of Madagascar. XII. Resurrection and taxonomic revision of the genera Mediusella (Cavaco) Hutchinson and Xerochlamys Baker (Sarcolaenaceae), Adansonia (3) 31 (2), pp. 311-339 : 318-319

2. Mediusella bernieri (Baill.) Hutchinson

The Families of Flowering Plants Arranged According to a New System Based on their Probable Phylogeny: 347- 348 (1973). — Leptolaena bernieri Baill. , Bulletin de la Société linnéenne de Paris 1: 564 (1886). — Xerochlamys bernieri (Baill.) H.Perrier , Bulletin de la Société botanique de France 128: 59 (1931). — Type: Madagascar, Prov. Antsiranana, Vohémar, [13°21’S, 50°00’E], 1835, fr., Bernier 365 (holo-, P! [4 sheets: P00389104-06, P00490752]).

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Prov. Antsiranana, Ambararata , route de Daraina, 50 km d’Ambilobe, 13°01’15”S, 49°26’26”E, 79 m, 29. V.2005, Hong-Wa et al. 253 ( CNARP, MO, P, TAN) . — Andrafiamena, [12°57’S, 49°19’E], 759 m, 19. I.1954, Service Forestier 8223 ( P, TEF) . — Ankotekona , massif de l’Ankotekona au sud de Mangaoka, [12°19’S, 49°04’E], 100-150 m, 3.II.1966, Service Forestier 24465 ( P, TEF) . — Daraina, forêt de Solaniampilana-Maroadabo, 13°10’36”S, 49°41’54”E, 110 m, 5.III.2004, Gautier et al. 4424 ( G, MO) . — Idem, Bekaraoka Sud, 13°10’36”S, 49°41’54”E, 167 m, 31. V.2005, Hong-Wa et al. 268 ( CNARP, MO, P, TAN) . — Idem , Hong-Wa et al. 269 ( CNARP, MO, P, TAN) . — Idem, Bekaraoka Sud, 13°10’28”S, 49°41’50”E, 153 m, 1. VI.2005, Hong- Wa et al. 286 ( CNARP, MO, P, TAN) . — Idem, forêt d’Antsaharaingy, 12°55’S, 49°40’E, 75 m, 3.III.2005, Nusbaumer & Ranirison 1534 ( G, MO, P) . — Idem, forêt de Bekaraoka, 13°60’29”S, 49°42’14”E, 185- 460 m, 17.II.2004, Ranirison & Nusbaumer 453 ( G, MO) . — Idem, piste d’Ambohitsitondroina , 7 km au sud-ouest de Befarafara, 25.X.2003, Ratovoson et al. 754 ( CNARP, MO, TAN) . — Idem, Ratovoson et al. 761 ( CNARP, MO, TAN) . — Irodo, 12°38’33”S, 49°30’15”E, 59 m, 27. V.2005, Hong-Wa et al. 249 ( CNARP, MO, P, TAN) . — Sahafary , Andranomadiro, 10 km à l’ouest d’Irodo, 12°36’24”S, 49°26’21”E, 190 m, 27.VII.2004, Be et al. 52 ( CNARP, MO, P, TAN) . — Idem, forêt de Sahafary, 12°34’36”S, 49°27’41”E, 180 m, 24.VII.2004, Guittou et al. 33 ( MO) . — Idem, 12°36’18”S, 49°26’35”E, 270 m, 26. V.2005, Hong-Wa et al. 206 ( CNARP, MO, P, TAN) . — Idem, 12°36’34”S, 49°27’27”E, 282 m, 26. V.2005, Hong-Wa et al. 217 ( CNARP, MO, P) . — Idem , 26. V.2005, Hong-Wa et al. 218 ( CNARP, MO) . — Idem , forêt d’Andrafiabe, 12°34’34”S, 49°27’37’ E, 271 m, 10.IX.2004, Rakotondrafara et al. 271 ( CNARP, MO, P, TAN) . — Idem, plateau de Sahafary, 12°35’S, 49°26’5”E, 123 m, 24.II.2001, Razafitsalama & Ludovic 8 ( MO, TAN, TEF) . — Idem , bassin de la Saharenana, forêt de Sahafary, [12°34’S, 49°26’E], 100-300 m, 25.IV.1963, Service Forestier 22704 ( MO, P, TEF) . — Idem , 26.II.1964, Service Forestier 23317 ( K, MO, P, TEF) . — Vohémar, [13°21’S, 50°00’E], 1846, Bernier 2537 ( P) . — Without precise locality, Baron 6182 ( K, P) .

DESCRIPTION

Shrubs to small trees 8 m tall, trunk to 20 cm dbh. Leaf blades bright green above, dull green to sometimes whitish beneath, broadly ovate, 3-6 × 2-4 cm, flat, sub-bullate, base rounded to cordate, margin revolute, apex obtuse to rounded or sometimes acute, midrib yellowish, slightly sunken above, distinctly raised beneath, secondary veins conspicuous, 5-12 per side, 4-9 mm apart; petiole 6-11 mm long. Flowers rarely solitary, usually in inflorescences, terminal, with 2-(3) flowers; peduncle 1-2 mm long, glabrous, pedicel 1-2 mm long, glabrous. Involucre green, urceolate, 3-10 × 3-8 mm, 0.7-1 mm thick, teeth 8-10, 0.5-1.8 mm long; flowers 14-22 mm long at anthesis from apex of pedicel to apex of petals; sepals 4-6 × 3-4 mm; petals white to pale yellow, 11-16 × 5-10 mm, exceeding the involucre by 7-11 mm; disc 1-4 mm tall; stamens 20-50, 6- 12 mm long; ovary 3-7 mm high, style 4-8 mm long, stigma 2 mm wide. Fruits ovoid, 6-11 × 4-9 mm, exceeding the accrescent involucre by 2-7 mm; seeds 5 × 3 mm, 2-3 per fruit.

PHENOLOGY

Flowering and fruiting from February to July.

VERNACULAR NAME

Zahana.

HABITAT

Dry forests on sandstone, limestone and metamorphic and igneous rocks from 50 to 300 m in the dry bioclimatic zone.

DISTRIBUTION

From Ankotekona to Vohémar in NE Madagascar ( Fig. 1 ).

REMARKS

Mediusella bernieri can be recognized by its broadly ovate leaf blades that are bright green above and dull green to sometimes whitish beneath, with an obtuse to rounded, sometimes slightly acute apex, and revolute margins; the prominent venation often makes them appear sub-bullate. Its flowers are pale yellow and its fruits are longer than the woody involucre.

CONSERVATION STATUS

Mediusella bernieri is known from nine subpopulations in an area of occupancy of 108 km 2 and an extent of occurrence of 3055 km 2. It is restricted to the northern part of Madagascar but is locally abundant, particularly in the region of Daraina. However, none of the subpopulations occurs in a protected area, which suggests a projected population reduction within three generations due to habitat destruction. This species is provisionally considered to be Endangered [EN A3c; B1ab(i, ii,iii,iv)+2ab(i,ii,iii,iv)].

Figures

FIG. 1. — Distributions of Mediusella arenaria (F.Gérard) Hong-Wa (▲), M. bernieri (Baill.) Hutchinson (✚), Xerochlamys itremoensis Hong-Wa, G.E.Schatz & Lowry (●) and X. undulata Hong-Wa (■) mapped on the bioclimatic zones of Madagascar (after Cornet [1974], simplified by Schatz [2000]).