Xerochlamys undulata, Hong-Wa, 2009

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 : 333-336

9. Xerochlamys undulata Hong-Wa, sp. nov.

( Fig. 6 )

Arbuscula , foliis ellipticis subtus pilosis ad apices retusis ad bases truncatis et ad margines undulatis, floribus terminalibus, involucro rubro piloso.

TYPUS. — Madagascar. Prov. Toliara, Ranohira, forêt d’Ankijabe , 22°39’58”S, 45°16’45”E, 871 m, 27. VI.2005, fl., Hong-Wa et al. 372 (holo-, MO!; iso-, G!, K!, P!, TAN!).

PARATYPES. — Madagascar. Prov. Fianarantsoa, 5 km east of Ilakaka, valley west of Isalo Mts , 825 m, 14.X.1970, Fosberg 52418 ( MO) . — Ankazomanga , 22°46’36”S, 45°01’28”E, 1067 m, 28. VI.2005, Hong-Wa et al. 386 ( MO, TAN) ; Hong-Wa et al. 387 (MO, P, TAN). — Ianakandrarezo , [22°35’S, 45°23’E], 14. VI.1967, Service Forestier 26379 ( P, TEF) . — Col des Tapia, near limit of Ihosy subdivision, 59 km east of Sakaraha , [22°47’S, 44°58’E], 900 m, 3.II.1975, Croat 30611 ( MO, TAN) . — Col des Tapias , [22°47’S, 45°00’E], Homolle 1548bis ( P) . — III.1960, Keraudren 455 ( MO, P) . — Idem, deuxième col des Tapia entre Ranohira et Sakaraha , 31.X.1960, Léandri 3506 ( MO, P) ; Leroy 3 ( MO) . — [22°46’S, 45°01’E], III.1970, Morat 3476 ( P, TAN) . — 500-1200 m, 26.II.1949, Service Forestier 549 ( MO, P, TEF) . — 514-1268 m, II.1955, Service Forestier 11660 ( P, TEF) . — Ihosy , [22°24’S, 46°08’E], Rauh 1506 ( MO) . — Ilakaka , [22°43’S, 45°11’E], III.1970, Morat 3603 ( P) . — 31.III.1966, Peltier 5785 ( P) . — [22°39’S, 45°13’E], 650 m, 29. V.1955, Service Forestier 14289 ( P, TEF) . — Lalanandro , [22°19’S, 46°07’E], 1245 m, 19.XII.1968, Service Forestier 28500 ( K, MO, P) . — Parc national d’Isalo , [22°08’- 22°40’S, 45°10’- 45°24’E], 514-1268 m, II.1956, Bosser 9182 ( MO, P, TAN) . — [22°36’S, 45°22’E], 800 m, 29. I.1955, Cours 5031 ( P) . — [22°45’S, 45°15’E], 31.X.1940, Decary 16281 ( P) . — [22°11’S, 45°10’E], Decary 16283 ( P) . — Idem, northwest of Ranohira , [22°33’S, 45°19’E], 800 m, 13.II.1990, Du Puy et al. MB668 ( MO, P, TAN) . — [22°36’S, 45°22’E], 800 m, 29. I.1955, Herbier de la Station agricole de l’Alaotra ( G. Cours) 5031 ( MO, P) . — Idem, forêt d’Ampandrabe , 22°36’51”S, 45°20’45”E, 905 m, 19.XII.2001, Hong-Wa & Ludovic 37 ( MO, P, TAN, TEF) . — Idem, plateaux et vallée de l’Isalo au col des Tapias , [22°47’S, 45°01’E], 1000 m, 28.XI-4.XII.1946, Humbert 19611 ( MO, P) . — Idem, à l’ouest de Ranohira , [22°11’S, 45°10’E], 800-1250 m, 19.XI.1960, 29.I-10.IV.1955, Humbert 28696 ( P) ; Humbert 28729 ( P) . — [22°08’S, 45°10’E], 800-1000 m, 30.VII.1928, Humbert & Swingle 5040 ( P) . — 14.X.1970, Keraudren-Aymonin & Aymonin 24675 ( P) . — Massif de l’Isalo à Betamanga , 1000-1300 m, 20.XI.1960, Léandri & Saboureau 3955 ( K, MO, P) . — Idem , south of 11 km Ranohira-Sakaraha, [22°39’S, 45°21’E], 900 m, 8.VIII.1995, Leeuwenberg & Rapanarivo 14619 ( K, MO, P, TAN, WAG) . — Isalo , 800 m, 6.XI.1978, Lorence 2069 ( K, MO, P, TAN) . — Idem , [22°11’S, 45°10’E], 900 m, X.1924, Perrier de la Bâthie 16594 ( P) ; Perrier de la Bâthie 16606 ( P) . — Idem , 22°38’34”S, 45°20’06”E, 820 m, 30.IV.1998, Randrianaivo et al. 226 ( MO) . — Idem, 34 km west of Ranohira along the Sahanafa trail, 22°16’30”S, 45°22’E, 1200-1500 m, 6.VII.1992, A. Randrianasolo 240 ( MO) . — Idem , [22°33’S, 45°25’E], 30.VII.1963, Rauh 10378 ( TAN) . — Ranohira , PK 712, [22°38’S, 45°20’E], 0-800 m, 23.VII.1955, Service Forestier 13897 ( P, TEF) . — [22°47’S, 45°00’E], 19.IV.1958, Service Forestier 18580 ( P, TEF) . — 23. V.1965, Service Forestier 24112 ( K, MO, P, TEF) . — [22°40’S, 45°16’30”E], 800- 1000 m, 11.VII.1992, A. Randrianasolo 243 ( MO) . — Sakaraha, 57 km south of Ranohira , [22°46’S, 45°01’E], 1000 m, 11.VII.1992, A. Randrianasolo 241 ( MO); A. Randrianasolo 242 ( MO) .

DESCRIPTION

Shrubs; young and older twigs pubescent. Leaf blades bright green above, dull green beneath, elliptic, 1-3.5 × 0.6-2 cm, chartaceous, abaxially sparsely pubescent, adaxially glabrous, base cordate occasionally truncate, margin undulate, erose, apex retuse, midrib reddish, flat to slightly sunken above, slightly raised beneath, secondary veins indistinct, 6-10 per side, 1-4 mm apart, looping 0.2-1.5 mm from the margin; petiole 3-7 mm long, pubescent. Flowers solitary or in inflorescences, terminal, with 2 flowers; peduncle 2-3 mm long, pubescent, pedicel 0.5-2.5 mm long, pubescent. Involucre reddish, urceolate, 2-7 × 3-9 mm, red tomentose interspersed with sparse white trichomes, teeth 9-20, 0.8-2 mm long; flowers 11-25 mm long at anthesis from apex of pedicel to apex of petals; sepals oblong, 4-7 × 3-5.5 mm, slightly emarginate, exserted 1-3 mm beyond the involucre; petals pale yellow to white, oblong, 9-17 × 5-8 mm, exceeding the involucre by 7-10 mm; disc 1-2.3 mm tall; stamens 18-23, 4- 10 mm long; ovary globose, 2-4 mm high, style 5-12 mm long, basally pubescent, stigma 0.3-1 mm wide. Fruits globose to ovoid, 4-9 × 4-11 mm, exceeding the accrescent involucre by 1-4 mm; seeds brown, ellipsoid, 2-4 mm long, 2-6 per fruit.

PHENOLOGY

Flowering and fruiting from October to July.

VERNACULAR NAME

Foto.

HABITAT

On sandstone from 500-1500 m within the subhumid and subarid bioclimatic zones.

DISTRIBUTION

Localized around Isalo National Park in SW Madagascar ( Fig. 1 ).

REMARKS

This species can be distinguished from X. bojeriana by its undulate, pubescent leaves, its long petiole (> 3 mm), its pale yellow to white flowers, and the red indumentum covering its involucre. Xerochlamys undulata occurs in the same area as X. villosa , but differs by its small leaf blades that are ≤ 3.5 cm long (vs.> 3.5 cm long in X. villosa ), and are elliptic and pubescent (vs. ovate and glabrous), its pale yellow to white (vs. white) petals, and its red pubescent (vs. yellow tomentose) involucre. Field observations show that the erose leaf margin of X. undulata (the blades appearing to have been eaten by insects) is widespread across individual plants and is a very distinctive feature of this species. Another striking pattern observed in the field is the tendency of X. undulata to grow in dense monospecific populations, interspersed with only few other plant species.

CONSERVATION STATUS

With an extent of occurrence of 3238 km 2, an area of occupancy of 72 km 2 and three subpopulations, only one of which occurs within the Isalo National Park, Xerochlamys undulata is assigned a preliminary conservation status of Endangered [EN B1ab(i, ii,iii,iv)+2ab(i,ii,iii,iv)].

Figures

FIG. 6. — Xerochlamys undulata Hong-Wa: A, leaf; B, flowering branch; C, D, fruit with and without involucre; E, flower. Hong-Wa 372. Scale bars: A, B, 1 cm; C-E, 5 mm.

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]).