Memecylon amplifolium 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 : 350-352

Memecylon amplifolium R.D.Stone , sp. nov.

( Fig. 8 )

Affinis M. perrieri Danguy sed laminis foliorum grandioribus (plerumque 5-7 × 2.5-4 non 3.5-4.5 × 1.5 cm) et late ellipticis differt.

TYPUS. — Madagascar. Antsiranana province, 79 km south of Antsiranana on Route nationale 6, 14.5 km east of the old building site of Colas à Marotaolana , camp 2 km before Anjahakely , 12°53’43”S, 49°18’27”E, alt. c. 550 m, dry semi-deciduous forest, 27. V.1997, Andrianantoanina & Bezara 1065 (holo-, CAS; iso-, MO, P).

PARATYPES. — Madagascar. Antsiranana province, Ambohipiraka, X.1932, Perrier 18761 ( P) . — Antsiranana province, calcaires lapiazés de l’Ankarana, près d’Anbondromifehy, 28.IV.1966, Capuron SF-24729 ( P) .

DESCRIPTION

Evergreen shrub to small tree 5 m high; branchlets terete, thickened at the nodes; internodes c. 1-2 cm long. Leaves coriaceous, dark green and shining on the upper surface, paler and dull on the lower, drying brownish and rugose on both surfaces; petiole distinct but very short, robust, flattened on the adaxial side; blades obovate to broadly elliptic, (4-) 5-7 cm long and (2-) 2.5-3.9 cm wide, cuneate at base, broadly short-acuminate and acute at apex (the acumen up to 5 mm long); mid-nerve impressed on the upper surface, ± prominent on the lower (especially toward the base); one pair of lateral nerves faintly visible on both surfaces, the course curvilinear and 3.5-5 mm from the margin in the basal half of the blade; transverse veins ± obscure. Cymules contracted, c. 1 cm long, generally solitary at the nodes below the current leaves or the “aphyllous” (scale-bearing) nodes alternating with those bearing normal leaves; peduncles 1-3 mm long, axes 1-3(-4) mm long; bracts deciduous. Flowers not seen. Fruits (immature?) ellipsoid, 7-9 mm long, 5.5-6 mm in diameter, on pedicels 1.5-2 mm long; calycinal crown spreading, 1 mm long, the margin thin and 4-emarginate between the ± truncate lobes.

REMARKS

This species belongs to a group of ellipsoid-fruited taxa that inhabit the dry forests of western and northern Madagascar. Others in this group include the widely distributed M. perrieri and the localized endemics M. buxifolium Blume and M. multinode Jacq. -Fél. Additional characters shared by these species are their coriaceous leaves drying brownish and their deciduous bracts.

Danguy (1922) described M. perrieri from a single flowering collection (Perrier 1048, P), but the taxonomy of this species has been in a confused state ever since. This is mainly because the species concept of Perrier de la Bâthie (1932, 1951) was based on discordant elements. He described the fruits of M. perrieri as oblong (11 mm long, 5 mm wide), but his circumscription included specimens in which the fruits are ellipsoid (Perrier 32, P) or globose (Pervillé 542, P). Jacques-Félix (1985b) later characterized the fruit of M. perrieri as globose, again based on Pervillé 542 (which is furthermore part of the original material of M. myrtiforme Naudin ). Although the proper determination of the Pervillé specimen remains unclear, it is entirely different from M. perrieri and must be excluded from that species. It is also different from M. myrtiforme (lectotypified by Wickens [1976], based on Du Petit-Thouars s.n., P, barcode no. 62664).

As now conceived, M. perrieri includes several specimens with fruits that are clearly ellipsoid (Perrier 32, P; Herb. Jard. Bot. Tananarive 6171, P; Humbert 32555, MO, P; Rahanyamalala s.n. in 1990, P; Schatz 2989, CAS, MO, P; Noyes et al. 1070, MO, P). Its circumscription also includes all of the material previously assigned to M. ankarense H.Perrier. The fruit of M. ankarense has been described as globose and 15 mm in diameter ( Perrier de la Bâthie 1932, 1951; Jacques-Félix 1985b), but this was based on a single example in very poor condition, found in an envelope on an isotype sheet (Perrier 1191, P, barcode no. 57714). In all other respects the type of M. ankarense is indistinguishable from M. perrieri , and there is no doubt that the two are conspecific.

Although M. amplifolium might be regarded as a large-leaved form of M. perrieri , there are two factors that argue against this. First, the leaves of M. amplifolium are distinctly larger and do not seem to represent one extreme in a continuous range of variation in M. perrieri . Second, one does not find these large-leaved plants occasionally throughout the distribution of M. perrieri ; they have instead a coherent range in a limited area of Antsiranana province.Additional collections from the Sahafary forest, Saharenana river basin (Capuron SF-24494, 24506, P), previously included in M. perrieri (Jacques-Félix 1985b) , are similar to M. amplifolium except that the leaf blades are broadly oblanceolate with the bases attenuate. It may eventually be necessary to include these specimens in the circumscription of M. amplifolium , or alternatively the Sahafary population could warrant recognition as yet another localized endemic.

Figures

FIG. 8. — Memecylon amplifolium R.D.Stone: A, habit; B, fruit. A, Andrianantoanina & Bezara 1065; B, Capuron SF-24729. Scale bars: A, 5 cm; B, 3 mm.