Memecylon interjectum 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 : 348-350

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

( Fig. 7 )

Similis M. perangusto Jacq.-Fél. sed laminis latioribus, inflorescentiis plerumque ad nodos inferiores defoliatos non in axillis foliorum, bracteis brevibus squamiformibusque non acicularibus, pedicellis longioribus differt.

TYPUS. — Madagascar. Antsiranana province, Masoala peninsula, canyon of the upper Ampanavoana river, 15°37’40”S, 50°04’30”E, alt. c. 250 m, shallow soil of steep, east-facing rock outcrop on west side of river, 10.XII.2001, Stone et al. 2408 (holo-, CAS; iso-, CAS, G, K, MO, P, TAN, TEF, UC, US, WAG; fruits in spirit collection at CAS) .

DESCRIPTION

Shrub 2 m high; branchlets narrowly 4-winged when young (the wings often slightly crisped), becoming terete with age; internodes 1.5-3.5 cm long; axils with a small tuft of persistent bristles 1.5-2 mm long. Leaves thin but firm (neither coriaceous nor papyriferous), bright green on the upper surface (when dry), somewhat paler below, both surfaces dull and finely granular-rugose; petioles 1.5-2.5 mm long; blades broadly lanceolate, 5-8 cm long, 1.5- 2.4 cm wide, cuneate at base, attenuate and acute or ± acuminate at apex; mid-nerve impressed on the upper surface, prominent and yellow-coloured on the lower; transverse veins scarcely visible, oriented at an oblique angle relative to the mid-nerve. Cymes 1.5 cm long, mostly 5-flowered, umbelliform or with a short axis above the peduncle, solitary or fascicled in the lower axils and also at the nodes below the current leaves; peduncles (1-)2-3(-4) mm long; bracts squamiform, deciduous; pedicels slender, 4- 6 mm long. Flowers not seen. Fruits globose, 5 mm in diameter; calycinal crown erect, 4-microdentate; epigynous chamber with partitions cruciform, scarcely pronounced.

REMARKS

This species is known only from the type collection. It has the acute leaf apices of M. perangustum but differs conspicuously from that species by its wider leaves (which in M. perangustum are mostly 0.9-1.5 cm wide, rarely to 1.9 cm). Another seemingly close relative, M. gracilipedicellatum Jacq. -Fél., differs from both of the aforementioned species in having leaf blades less than three times longer than wide with apices obtuse.

Here it must be mentioned that M. perangustum is somewhat variable in its leaf morphology. The type (Rakotoniaina RN-2365, P) has narrowly lanceolate leaves that are abruptly rounded and then narrowly cordate at the base, as does one other collection (Rakotoniaina RN-5928, P). In four other specimens from the type region, the leaf bases are gradually narrowed to the petiole and not at all rounded or cordate (Rakotoniaina RN-2431, Rakotoniaina RN-2634, Rakoto Jean de la Croix RN-7718, and Razanaparany RN-8748; all at P). A recent collection from the Réserve naturelle intégrale de Betampona (Andrianarisata 151, CAS, MO, P) has leaves less than six times longer than wide; these specimens do not key cleanly to M. perangustum in Jacques-Félix (1985a) and superficially resemble M. interjectum , but their acicular inflorescence bracts and short pedicels nonetheless identify them as M. perangustum .

Figures

FIG. 7. — Memecylon interjectum R.D.Stone: A, habit; B, infructescence. Stone et al. 2408. Scale bars: A, 5 cm; B, 5 mm.