Xerochlamys tampoketsensis F.Gérard

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 : 332-333

8. Xerochlamys tampoketsensis F.Gérard

Comptes rendus de l’Association française pour l’Avancement des Sciences 1914 (sess. 43): 409 (1915). — Type: Madagascar, Prov. Mahajanga, cimes gneissiques du Tampoketsa, entre le Bemarivo et l’Anjobona , [16°08’S, 48°02’E], VII.1905, fr., Perrier de la Bâthie 3032 (holo-, P! [2 sheets: P00389120-21 ]) .

Xerochlamys rupestris F.Gérard, Comptes rendus de l’Association française pour l’Avancement des Sciences 1914 (sess. 43): 408 (1915). — Type: Madagascar, Prov. Mahajanga, région du Cap St André, Mt. Ambohitrosy , rochers granitiques, [16°47’S, 45°01’E], V.1904, fr., Perrier de la Bâthie 3027 (holo-, P! [ P00389118 ]; iso-, P! [ P00389119 ]) .

ADDITIONAL MATERIAL EXAMINED. — Madagascar. Prov. Antananarivo, Analanomby , [19°45’S, 47°05’E], 2.IX.1937, Herbier du Jardin botanique de Tananarive 3027 ( P) . — Andranofeno-Sud , 18°04’53”S, 47°10’23”E, 1400 m, I.2000, Andrianjafy et al. 6 ( MO, P, TAN) . — Idem, 34 km north of Ankazobe along the route from Antananarivo-Mahajanga at PK 135, 18°04’53”S, 47°10’23”E, 1400 m, 4.III.2000, Schatz et al. 3947 ( MO) . — Tampoketsa d’Ankazobe, route Tananarive- Majunga , PK 184, [17°53’S, 47°03’E], IV.1958, Descoings 3286 ( MO, TAN) . — Idem, PK 181, [17°52’S, 47°04’E], 31. I.1972, Jacquemin 895 ( P) . — 23.II.1973, Jacquemin 1250 ( P) . — Idem, cimes du Tampoketsa au-dessus de Mahatsinjo , [17°52’S, 47°03’E], 1300 m, I.1927, Perrier de la Bâthie 17876 ( K, MO, P, TAN) . — Prov. Mahajanga, Antsiafabositra , 17°13’41”S, 46°59’55”E, 560 m, 7. V.2005, Andrianjafy et al. 1026 ( MO, P, TAN) . — Andrianjafy et al. 1033 ( MO, P, TAN) . — Beveromay, cime du Tampoketsa de Tsaratanana entre le Mahajamba et le Bemarivo , [16°47’S, 47°52’E], 1200 m, VII.1920, Perrier de la Bâthie 13214 ( P) . — Mahatsinjo , 17°49’55”S, 47°01’39”E, 1398 m, 16.VII.2005, Hong-Wa et al. 495 ( MO, P, TAN) . — Idem , sur le Tampoketsa, au sud de Mahatsinjo, [17°45’S, 45°01’E], VII.1925, Perrier de la Bâthie 17329 ( P) .

DESCRIPTION

Small trees 2-5 m tall, tortuous; young twigs tomentose, older twigs glabrous. Leaf blades dark green above, dull green beneath, elliptic to suboblong, 3-6 × 2-3 cm, subcoriaceous, white-pubescent when young, glabrous at maturity or trichomes restricted to the abaxial midvein, base rounded, margin plane, apex obtuse, sometimes rounded, midrib yellow, slightly sunken above, distinctly raised beneath, secondary veins prominent, 7-10 per side, 2.5-5 mm apart, looping 1-2.3 mm from the margin; petiole 3-7.5 mm long, pubescent. Flowers sometimes solitary or usually in inflorescences, terminal, with 2 flowers; peduncle 0.5-1 mm long, pubescent, pedicel 1-3 mm long, pubescent. Involucre brown, cupulate, 5-7 × 4-10 mm, with white trichomes, teeth 13-20, 1.2-2.4 mm long; flowers 20-30 mm long at anthesis from apex of pedicel to apex of petals; sepals oblong, 7-9 × 4-7 mm, slightly emarginate, exserted 3-4 mm beyond the involucre; petals pale yellow, oblong, 19-24 × 8-12 mm, exceeding the involucre by 14-17 mm; disc 2.7-3.3 mm tall; stamens 27-40, 11- 16 mm long; ovary ovoid, 2.7-4 mm high, style 11-12 mm long, pubescent, stigma 1 mm wide. Fruits globose to subglobose, 6-11 × 6-12 mm, exceeding the accrescent involucre by 2-8 mm; seeds black, flattened-ellipsoid, 3-4 mm long, 2-6 per fruit.

PHENOLOGY

Flowering and fruiting from January to July.

HABITAT

Dry habitats on gneiss and granite from 500-1400 m in subhumid and dry bioclimatic zones.

DISTRIBUTION

From near Cap St André to Tampoketsa d’Ankazobe and Tampoketsa d’Analamaitso in NW Madagascar ( Fig. 4 ).

REMARKS

This species can be recognized by its generally glabrous leaf blades that are sometimes pubescent along the midvein, its pubescent petiole, and its pale yellow flowers each subtended by a brown involucre.

Xerochlamys tampoketsensis is somewhat variable in leaf shape and size. On material with small (≤ 4 cm long) leaf blades (Descoings 3286, Perrier 3032), the blades are more or less suboblong; the former specimen also has leaves with a midrib bearing evident indumentum. Larger leaves (> 4 cm long), such as those found on Perrier 13214 and on Andrianjafy 1026 and 1033, are elliptic and glabrous. This variability appears to have led Cavaco (1952b) to regard the taxon recognized here as a variety of X. diospyroidea , especially because the small leaved specimens superficially seem comparable to material of the latter. However, X. tampoketsensis differs from X. diospyroidea by its suboblong to elliptic (vs. ovate to rounded) leaf blades, its white pubescence restricted to the midvein at maturity when present (vs. golden pubescence throughout the leaf surfaces), its pale yellow (vs. pink) petals and the number of seeds per fruit (2-6 vs. 3-12).

CONSERVATION STATUS

With an extent of occurrence of 19 780 km 2, an area of occupancy of 63 km 2, and six subpopulations, of which just one occurs in a protected area (Tampoketsa d’Analamaitso), X. tampoketsensis is provisionally classified as Vulnerable [VU B1ab(ii, iii,iv)+B2ab(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]).