Pentachlaena betamponensis Lowry, Haevermans, Labat & G.E. Schatz, 2000

Lowry Ii, Porter P., Haevermans, Thomas, Labat, Jean-Noël, Schatz, George E., Leroy, Jean-François & Wolf, Anne-Elizabeth, 2000, Endemic families of Madagascar. V. A synoptic revision of Eremolaena, Pentachlaena and Perrierodendron (Sarcolaenaceae), Adansonia (3) 22 (1), pp. 11-31 : 16-18

1. Pentachlaena betamponensis Lowry, Haevermans, Labat & G.E. Schatz , sp. nov.

Arbor, altitudine ignota. Folia petiolo 0.8-1.2 cm longo; lamina obovata, coriacea, 4-5 × ca. 3 cm, apice emarginata, margine integra, basi truncata, nervis secundariis 5- vel 6-jugatis. Inflorescentia terminalis, ramosa, ex floribus ca. 10 constans; axe primario 4-5 cm longo, parce stellato-strigoso; pedunculis 5-6 mm longis, dense stellato-strigosis; bracteis 4-5 × ca. 1 mm, anguste oblongis; involucro sub anthesi leviter undulato, margine dentato, 3-4 mm in diam., dense papilloso-strigoso, flores duos sessiles quemque ca. 3 cm in diam. includente. Flos sepalis 5 imbricatis coriaceis, leviter laciniatis, ca. 1 × 1 cm; petalis 5 obovatis, glabris, ca. 1.5 × 0.8-1 cm, apice rotundatis leviter emarginatis, basi breviter unguiculatis; staminibus 150 ad 200 vel plus; ovario 5-loculari subgloboso in alabastro elobato, sub anthesi lobulos celeriter evolvente, dense stellato-strigoso, ca. 3.5 × 1.5 mm; stylo ca. 3 mm longo, ca. 0.5 mm in diam., basi stellato-strigoso. Fructus ignotus.

TYPUS. — Réserves Naturelles (Razanaparany) 9158, Madagascar, Prov. Toamasina, Betampona RNI , [17°55’S, 49°13’E], 12 Nov. 1957, fl. (holo-, P!; iso-, TEF).

Trees (height unknown). Twigs covered with stellate indumentum. Leaves obovate, brown above, greenish-brown below (in dry material), coriaceous, 4-5 × 3 cm, with scattered papillate stellate indumentum with curly branches on abaxial surface, later becoming glabrous to subglabrous, apex emarginate, margin entire, base truncate, venation brochidodromous, with 5-6 pairs of secondary veins, midrib weakly channeled above, raised below; petiole 0.8-1.2 cm long, with sparse stellate indumentum, adaxially canaliculate; stipules unknown, caducous, scars inconspicuous. Inflorescences terminal, branched, with ca. 10 flowers, primary axes 4-5 cm long, sparsely stellate-strigose, peduncles 5-6 mm long, densely stellate-strigose; bracts 4-5 × 1 mm, narrowly oblong; involucre in flower weakly undulate, margin toothed, 3-4 mm in diam., densely papillate strigose, enclosing 2 sessile flowers each ca. 3 cm in diam.; sepals 5, imbricate, coriaceous, margin slightly laciniate, ca. 1 × 1 cm, glabrous and papyraceous where covered by adjacent sepals, densely stellate strigose where exposed; petals 5, contorted in opposite direction from sepals, obovate, glabrous, 1.5 × 0.8-1 cm, apex rounded, slightly notched, claw short; extrastaminal disc 1 mm high, with an irregular margin; stamens ca. 150-200 or more, filaments ca. 5 mm long, anthers 1 × 1 mm, basifixed; ovary subglobose, not lobed in bud, but becoming so at anthesis, densely stellate-strigose, 3.5 × 1.5 mm, locules 5, number of ovules unknown; style 3 mm long, 0.5 mm in diam., stellate-strigose at base, stigma crateriform with a distinctly undulate margin. Fruits unknown. — Fig. 2 .

This species, known only by the type specimen collected at Betampona RNI ( Fig. 3 ), is easily distinguished by its comparatively small, obovate leaves and branched, 10-flowered inflorescence. It also differs from the other humid forest member of the genus, P. orientalis , by its smaller flowers and entire rather than distinctly laciniate bracts.

VERNACULAR NAME. — Amaninombilahy.

Figures

Fig. 2. — Pentachlaena betamponensis: A, flowering branch; B, leaf (abaxial surface); C, petiole; D, flower at anthesis; E, flower (schematic transverse section); F, petal. (Service Forestier 9158). — Drawn by A. JOUY and A. BERTHELOT.

Fig. 3. — Distributions of Pentachlaena, mapped on the simplified bioclimatic zones of Madagascar (SCHATZ in press, after CORNET 1974). P. betamponensis (*), P. latifolia (•), P. orien- talis (Δ).