Memecylon impressivenum R.D.Stone, 2006

Stone, Robert Douglas, 2006, New species of Memecylon L. and Warneckea Gilg (Melastomataceae) from Madagascar and Mayotte, Adansonia (3) 28 (2), pp. 337-358 : 348

publication ID 10.5281/zenodo.5187074

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scientific name

Memecylon impressivenum R.D.Stone

sp. nov.

Memecylon impressivenum R.D.Stone View in CoL , sp. nov.

( Fig. 6 View FIG )

Similis M. inalato Jacq.-Fél. a quo ramulis junioribus anguste quadrialatis non teretibus, foliis parvioribus ad apices late obtuseque acuminatis, venis transversis in paginis superioribus foliorum conspicue impressis, pedunculis brevioribus, floribus subsessilibus differt.

TYPUS. — Madagascar. Antsiranana province, Masoala peninsula, canyon of the Ampanavoana river , 15°40’45”S, 50°09’35”E, alt. c. 150 m, understory of evergreen rain forest, relatively dry site on small spur ridge west of river, 8.XII.2001, Stone et al. 2406 (holo-, CAS; iso-, CAS, G, K, MO, P, TAN, TEF, UC, US, WAG) GoogleMaps .


Evergreen shrub 2-3 m high; branchlets quadrangular and narrowly 4-winged when young (the wings ± straight to slightly crisped), becoming terete with age and thickened at the nodes; internodes 2-4 cm long. Leaves subcoriaceous, sessile or nearly so (petioles up to 1 mm long), dark green and somewhat shining on the upper surface, paler and dull beneath, rugose on both surfaces (when dry); blades elliptic-ovate, 3.5-5.5 cm long, 1.5- 2.5 cm wide, gradually rounded toward the base then narrowly subcordate above the petiole, apex broadly acuminate (the acumen c. 5 mm long, obtuse); mid-nerve impressed on upper and lower surfaces; transverse veins oriented at an oblique angle relative to the mid-nerve, conspicuously impressed on the upper surface, obscure on the lower; lateral nerves situated 1-1.5 mm from the margin; young leaves strongly violaceous. Cymes umbelliform, 1- 5-flowered, axillary and solitary but often opposite, often hidden beneath the leaves; peduncles filiform, 1-2 cm long, quadrangular and narrowly 4-winged; bracts lanceolate, 1-2 mm long, the bracteoles similar but smaller. Flowers subsessile, ochroleucous; hypantho-calyx campanulate, c. 2 mm long and 2.8 mm wide; calyx shallowly 4-lobed, the lobes broadly rounded. Corolla rounded and apiculate in bud; petals suborbicular, 2 mm long, 1.5 mm wide, apiculate, the margins scarious. Anthers 1.5 mm long, the connective shortly conical and ± incurved but lacking a dorsal gland, the pollen sacs occupying more than half the length on the ventral side; filaments c. 1.5 mm long. Style c. 3 mm long. Fruits not seen.


This species is known only from the type collection. The long, slender peduncles and anthers lacking a dorsal gland suggest a close relationship with M. alatum Aug.DC. , M. mocquerysii Aug.DC. , and M. inalatum . It is perhaps most similar to M. inalatum which is based on a fruiting specimen (Capuron SF-24056, P) from Toamasina province, Analalava forest on laterite west of Foulpointe (approximately 230 km to the south). A recent collection from the eastern Masoala peninsula, Aridy 123 (CAS, MO, P, TAN), is tentatively included in the circumscription of M. inalatum , although it differs from the type in some details (i.e. the somewhat smaller leaves with transverse veins obscure and the peduncles which are less than 3 cm long and quadrangular in cross-section). Aridy 123 has mainly fruits, but the specimen at CAS also has flower buds that are identical to those of M. impressivenum .

Another species with umbellate cymules on long, axillary peduncles is the Tanzanian M. cogniauxii Gilg , under which M. mocquerysii was previously placed as a synonym (Jacques-Félix 1985a: 432). While these two species superficially resemble one another, their branchlets and floral characteristics are remarkably different, and phylogenetic analyses of DNA sequences place M. cogniauxii in a separate group along with most of the other east- African species sampled thus far ( Stone 2004 and unpubl. data).


California Academy of Sciences


Conservatoire et Jardin botaniques de la Ville de Genève


Royal Botanic Gardens


Missouri Botanical Garden


Museum National d' Histoire Naturelle, Paris (MNHN) - Vascular Plants


Parc de Tsimbazaza


Centre National de la Recherche Appliquée au Developement Rural


Upjohn Culture Collection


University of Stellenbosch


Wageningen University

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