Memecylon longipes R.D. Stone, 2022

Stone, Robert Douglas, 2022, Ten new species of Memecylon (Melastomataceae) from Madagascar, Candollea 77 (1), pp. 81-103 : 94-96

Memecylon longipes R.D. Stone , sp. nov. ( Fig. 8 ).

H o l o t y p u s: MADAGASCAR. R e g. S AVA [Pr o v. Antsiranana]: Vohémar, Tsarabaria, Manakana , Ambondrombe , 13°42'46"S 50°05'25"E, 18. V.2004, fr., Rabehevitra et al. 1033 ( P [ P05206873 ]!; iso-: CAS-1065645!, G [ G00415905 ]!, MO-4777798!) .

Aff ine Memecyloni ambrensi Jacq.-Fél. et M. arenicolae R.D. Stone , sed a primo internodiis brevibus plerumque 2.5–5 cm (non 5–8 cm) longis et foliis minoribus 5–10 cm × 3–6 cm (non usque ad 14 × 8 cm), ab ambobus fructuum pedicellis sursum dilatatis, fructu basi plusminusve truncata incrassataque et apice sub corona calycinali prominente constricto differt.

Evergreen trees 5 – 7 m high; young branchlets terete, c. 2 mm thick, surface smooth, chocolate brown; older branchlets c. 4 mm thick, lighter brown, finely longitudinally fissured; nodes thickened; internodes (1–)2.5–5(–6.2) cm long. Leaves coriaceous, sessile, dull green on the upper surface, dull green or brown on the lower; blades elliptic, 5–10 × 3–6 cm, base rounded to subcordate, apex rounded to obtuse or retuse; midnerve finely canaliculate adaxially, somewhat prominent abaxially especially towards the base of the blade; transverse veins scarcely visible, c. 8 pairs, oriented at an oblique angle relative to the midnerve, weakly prominent on both surfaces or ± obscure abaxially, confluent with the equally weak lateral nerves c. 2–3 mm from the margin. Flowers unknown. Infructescences solitary or fascicled in groups of 2– 3 at the defoliated nodes of upper branchlets (rarely in the lower leaf axils); peduncles stout, 1 – 4 mm long, often extended by a short internode 1–1.5 mm long; bracts triangular-cucullate, 1–1.5 mm long, rapidly deciduous. Fruiting pedicels 7–9 mm long, slender towards the base, becoming dilated upwards and confluent with the base of the fruit. Fruits ellipsoid-urceolate, (10–)12–15(–17) × 8–11(–12) mm, base ± truncate beneath a ± conspicuous torus (thickened rim), apex constricted beneath the persistent calycinal crown c. 1.5 × 3 mm, calyx margin conspicuously sinuate-dentate; stylopodium prominent, ± filling the epigynous chamber.

Etymology. – The epithet longipes is a compound derived from the Latin adjective longus meaning “long” and the noun pes meaning “foot”. It functions as an adjective and refers to the long and upwardly dilated fruiting pedicels of this species.

[A: Rabevohitra et al. 5152, MO; B–D: Rabehevitra et al. 1033, CAS] [Drawing: S. Burrows]

Distribution and ecology. – Northeastern coast of Madagascar (SAVA region), near the village of Ambondrombe c. 37 km S of Vohémar. Habitat in littoral forest on sand.

Conservation status. – Memecylon longipes is known from two locations with an estimated AOO of 8 km ². The coastal area and littoral forests to the south of Vohémar do not currently receive any formal protection, in spite of the fact that the Ambondrobe [Ambondrombe] forest where this species occurs was recommended for protected area status ( CONSIGLIO et al., 2006). Anthropogenic threats in this area are evidently not well documented. Based on its limited AOO, M. longipes is provisionally assessed as “Critically Endangered” [CR B1ab(iii)+B2ab(iii)] in accordance with the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – Memecylon longipes is closely related to M. ambrense Jacq. -Fél. and M. arenicola R.D. Stone , as evidenced by several shared characters including their thick, terete branchlets; sessile, elliptic to broadly elliptic leaves that are rounded to subcordate at base and ± rounded at the apex; and fruits with stylopodium prominent and ± filling the epigynous chamber. All three species are endemics of extreme northern Madagascar but are wholly allopatric, with M. ambrense restricted to the volcanic Montagne d’Ambre massif and both M. longipes and M. arenicola found only along the eastern coast and separated from each other by a distance of 44 km. The ellipsoid fruits of M. longipes , with their characteristically dilated pedicels, annular thickening above a ± truncate base, and conspicuously 4-dentate calycinal crown, are very different from the globose fruits of M. arenicola . The flowers of both species remain unknown.

Additional specimens examined. – MADAGASCAR. Reg. SAVA [Prov. Antsiranana]: Vohémar, Tsarabaria, Manakana , à l’Est du village d’Ambondrombe , 13°41'48"S 50°05'18"E, 14.III.2004, fr., Rabevohitra et al. 5152 ( CAS, MO, P, TEF) .

Figures

Fig. 8. – Memecylon longipes R.D. Stone. A. Fruiting branch; B, C. Leaves; D. Fruit.