Xerochlamys diospyroidea (Baill.) Baker

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 : 326-329

5. Xerochlamys diospyroidea (Baill.) Baker ,

Journal of the Linnean Society, Botany 25: 296 (1889). — Sarcolaena diospyroidea Baill. , Bulletin de la Société linnéenne de Paris 1: 565 (1886). — Leptolaena diospyroidea (Baill.) Cavaco , Bulletin du Muséum national d’Histoire naturelle, 2 e sér., 23: 135 (1951). — Type: Madagascar, Prov. Fianarantsoa, Ambatomenaloha, [20°37’S, 46°33’E], 1876, fl., Grandidier 62 (holo-, P! [P00047871]).

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Prov. Fianarantsoa, Itremo , [20°32’S, 46°33’E], 1700 m, IX.1956, Bosser 10022 ( P, TAN) . — 1964, Bosser 18876 ( P, TAN) . — Idem, along road between Finandrahana and Itremo , 27-40 km west of Finandrahana , 1400- 1500 m, 26. I.1975, Croat 29847 ( MO, TAN) . — [20°33’S, 46°36’E], 1300-1400 m, 27. I.1975, Croat 29899 ( MO, TAN) . — Idem , 20°36’38”S, 46°35’03”E, 1570 m, 18.VIII.2003, Hong-Wa et al. 144 ( MO, P, TAN) . — Idem, massif de l’Itremo, Ianasana , 20°34’08”S, 46°35’44”E, 1433 m, 23. VI.2005, Hong-Wa et al. 350 ( MO, P, TAN) ; Hong-Wa et al. 351 (MO, P, TAN). — Hong-Wa et al. 352 (MO, P, TAN). — Idem, montagnes ouest d’Itremo , [20°32’S, 46°33’E], 1500-1700 m, 17- 22. I.1955, Humbert 28153 ( MO, P) . — Idem , 20°35’09”S, 46°35’46”E, 1440 m, 23.III.1999, Labat et al. 3029 ( B, G, K, MO, P, TAN, WAG) . — 20°35’34”S, 46°35’37”E, 1410 m, 26.III.1999, Labat et al. 3038 ( B, G, K, MO, P, TAN, WAG) . — Idem, Antsirakambiaty , 20°35’22”S, 46°34’01”E, 1830 m, 27.III.1999, Labat et al. 3052 ( B, G, K, MO, P, TAN, WAG) . — Idem , 20°58’45”S, 46°58’73”E, 1513 m, 23.II.2001, Ludovic & Razafitsalama 4 ( MO, P, TAN, TEF) . — Idem, Ianasana, 7 km à l’ouest d’Itremo , 20°36’06”S, 46°34’18”E, 1630 m, 1.II.1999, Messmer & Andriatsiferana 750 ( G, MO, P) . — [20°32’S, 46°33’E], 1300-1800 m, XI.1970, Morat 3659 ( P, TAN) . — [20°34’S, 46°38’E], 1500 m, II.1919, Perrier de la Bâthie 12486 ( P) . — [20°36’S, 46°32’E], 1500 m, 6-8.III.1999, Rabenantoandro et al. 63 ( MO, P, TAN) . — Idem, route to Morondava, 42.5 km west of Ambatofinandrahana , [20°35’S, 46°36’E], 1500 m, 6.VII.1992, A. Randrianasolo 234 ( MO) . — Idem, eastern margin of the Itremo Massif, c. 19 km west of Ambatofinandrahana , 20°34’21”S, 46°34’54”E, 1580- 1700 m, 10.III.2000, Schatz et al. 3960 ( MO, P) . — Idem , Anasana, PK 112, [20°32’S, 46°33’E], 3.VIII.1959, Service Forestier 19503 ( P, TEF) . — Idem , rive droite de l’Ambatorangotana, massif de l’Itremo, [20°34’S, 46°35’E], 1650-1700 m, 21.II.1970, Service Forestier 29042 ( MO, P, TEF) . — Around Ambatofinandrahana , [20°33’S, 46°48’E], 17.II.1938, Decary s. n. ( TAN) . — Rauh 799 ( TAN) . — Mt. Ambatomenaloha ( Itremo massif), [20°37’S, 46°33’E], 1500 m, 17. I.1955, Service Forestier 11551 ( K, P, TEF) .

DESCRIPTION

Shrubs to small trees; young twigs tomentose, older twigs pubescent. Leaf blades dark green above, lighter beneath, ovate to rounded, rarely elliptic, 2-4.5 × 1.5-3.4 cm, subcoriaceous, densely covered with erect golden trichomes, base rounded, margin revolute, apex obtuse to emarginate, midrib visible only beneath, secondary veins indistinct, 6-10 per side, 2.5-4 mm apart, looping 1-3.5 mm from the margin; petiole 2-5 mm long, pubescent. Inflorescences terminal sometimes axillary, with 2-8 flowers; peduncle 1-3 mm long, pubescent, pedicel absent to 0.5 mm, pubescent. Involucre brown, cupulate, 3-10 × 4-10 mm, with dense golden trichomes, teeth 18-27, 1- 3.2 mm long; flowers 15-25 mm long at anthesis from apex of pedicel to apex of petals; sepals oblong, 6-10 × 3-7 mm, deeply emarginate, exserted 1-4 mm beyond the involucre; petals dark pink fading to white, oblong, 12-24 × 5-13 mm, exceeding the involucre by 9-14 mm; disc 2-3 mm tall; stamens 20-44, 8- 17 mm long; ovary ovoid, 3 mm high, style 6-14 mm long, pubescent, stigma 0.5-1 mm wide. Fruits subglobose to globose, 6-10 × 7-10 mm, exceeding the accrescent involucre by 2-5 mm; seeds brown, ellipsoid 2-4 mm long, 3-12 per fruit.

PHENOLOGY

Flowering and fruiting from October to June.

VERNACULAR NAMES

Kitoto.

HABITAT

Xerochlamys diospyroidea is one of the dominant elements of the evergreen sclerophyllous Uapaca bojeri (tapia) woodland in the Itremo massif, occurring on quartzite, marble, and metamorphic and igneous substrates from 1100-1800 m in the subhumid bioclimatic zone.

DISTRIBUTION

In central Madagascar in the area around Itremo ( Fig. 4 ).

REMARKS

Xerochlamys diospyroidea can be easily recognized by its dense golden indumentum that covers the flattened young twigs, both surfaces of the leaves and the involucre, its leaf blades less than 5 cm long, and its dark pink flowers fading to white at maturity.

The type specimen of this species (Grandidier 62) has relatively small (<3 cm long) elliptic leaf blades with an acute apex, while all other specimens collected from the same region have larger, more or less ovate to round leaf blades with an obtuse to rounded apex. However, Humbert 28153 has lamina of both shapes: the specimen at MO and the one of duplicates at P have small elliptic and acute leaf blades corresponding to those of the type, whereas the other specimen at P has four fragments, three with small elliptic blades and one with larger rounded blades. Apart from differences in leaf shape and size, indumentum density varies slightly between the two forms. It is unclear whether the two entities comprising Humbert 28153 represent different developmental stages of the same individual or were collected from separate plants; they are both in flower. The elliptic form is the less common of the two, but both come from the same area and are certainly variants of the same taxon, perhaps occurring in different habitats, or possibly one of them displaying post-fire morphology. Despite this variation, both forms can be easily distinguished from other co-occurring species such as X. itremoensis , which is glabrous, X. elliptica , which is also glabrous and moreover differs in having mostly white flowers (vs. dark pink fading to white at senescence in X. diospyroidea ), and X. bojeriana , which is pubescent, but has white trichomes and small leaf blades (<3 cm long) and short petiole (<3 mm long). Field observations also indicate that these four species distinctly differ in growth form; X. diospyroidea is a dense, erect shrub to a small tree, X. bojeriana is a slender, erect shrub, X. elliptica is a small tree, and X. itremoensis is a prostrate shrub.

CONSERVATION STATUS

Xerochlamys diospyroidea is a very abundant local endemic from the Itremo massif, and has not been recorded within a protected area. With an extent of occurrence of 468 km 2, an area of occupancy of 63 km 2, and only five known subpopulations, this species is preliminarily assigned a status of Endangered [EN B1ab(i,ii,iii,iv)+2ab(i,ii,iii,iv)].

Figures

FIG. 4. — Distributions of Xerochlamys elliptica F.Gérard (Å), X. diospyroidea (Baill.) Baker (▲), X. tampoketsensis F.Gérard (■) and X. villosa F.Gérard (●) mapped on the bioclimatic zones of Madagascar (after Cornet [1974], simplified by Schatz [2000]).