Memecylon xiphophyllum 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 : 344-346

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

( Fig. 4 )

A M. subsessili H.Perrier ramulis crassioribus, laminis foliorum multo longioribus (usque ad 40 cm) ad apices acutis non conspicue acuminatis, cymulis ad nodos strumosos ramulorum vetustiorum non in axillis foliorum, floribus grandioribus, bracteis caducis non persistentibus differt.

TYPUS. — Madagascar. Toamasina province, 8 km west of Foulpointe [Mahavelona], Analalava forest , 17°42’30”S, 49°26’50”E, alt. 60 m, north-facing slope in deeply shaded understory of evergreen rain forest on laterite, 17.XI.2001, Stone et al. 2393 (holo-, CAS; iso-, G, K, MO, P, TAN, US; flower buds in spirit collection at CAS) .

DESCRIPTION

Evergreen small tree; branchlets terete and thick (up to 7 mm in diameter), leafy only at the apex, with age becoming conspicuously swollen at the nodes; internodes 5-7 cm long. Leaves subcoriaceous, sessile or nearly so, yellowish green on the upper surface (when dry), bright to pale green or violaceous on the lower, very finely granular-rugose on both surfaces; blades narrowly lanceolate, 20- 40 cm long, 4-6.5 cm wide, rounded and narrowly cordate at base, long-attenuate and sharply acute at apex; mid-nerve canaliculate on the upper surface, dark and prominent on the lower, very wide at the base (up to 4.5 mm), becoming progressively narrower toward the apex; transverse veins clearly visible on both surfaces (especially the lower), perpendicular to the mid-nerve and spaced 6-10 mm apart, ± straight or occasionally forked; lateral veins situated 2-3 mm from the margin; young leaves strongly violaceous. Cymes contracted, c. 1 cm long, generally 3-flowered, fascicled at nodes well below the leaves; peduncles c. 2 mm long, axes 1-2 mm long (true pedicels lacking); bracts early deciduous, the bracteoles 1.5 mm long, lanceolate, carinate. Flowers at anthesis not seen; hypantho-calyx obconic in bud, 6.5 mm long, 4.5 mm wide, minutely granular on the outer surface, the margin 4-lobed, the lobes c. 1 mm long, broadly rounded, apiculate. Corolla acute; petals violet, ovate, 2.5 mm long, 2 mm wide, base broadly rounded, apex attenuate and acute. Anthers 2 mm long, the extremity of the connective abruptly and narrowly conical, the dorsal gland crateriform and medially positioned,

A

the pollen sacs occupying greater than half the length on the ventral side; filaments short. Style c. 2 mm long; ovules 9. Fruit unknown.

REMARKS

Memecylon xiphophyllum is known only from the type collection. It somewhat resembles M. subsessile , notably in its terete branchlets, narrowly lanceolate and basally cordate leaves, and transverse veins more or less perpendicular to the mid-nerve. The details of the hypantho-calyx and the anthers are also similar in the two species. Memecylon subsessile differs however in its slender branchlets, much smaller leaves that are short-petioled at the base and strongly acuminate at the apex, and smaller flowers borne in axillary cymes with bracts persistent.

The thick branchlets and foliar mid-nerves of M. xiphophyllum are similar to those of M. crassinerve Blume (an endemic of Nosy-Be island off the northwestern coast of Madagascar), but the broadly oblong and apically rounded leaves of M. crassinerve are completely different.

Figures

FIG. 4. — Memecylon xiphophyllum R.D.Stone: A, leafy branchlet; B, flowering branchlet; C, flower bud just before anthesis; D, same flower bud with petals and stamens removed; E, anther (side view); F, anther (oblique view of dorsal face). Stone et al. 2393. Scale bars: A, 10 cm; B, 5 cm; C, D, 2 mm; E, F, 1 mm.