Memecylon draconopterum R.D. Stone, 2022

Stone, Robert Douglas, 2022, Ten new species of Memecylon (Melastomataceae) from Madagascar, Candollea 77 (1), pp. 81-103 : 86-88

Memecylon draconopterum R.D. Stone , sp. nov. ( Fig. 3 ).

Holotypus: MADAGASCAR. Reg. Atsinanana [Prov. Toamasina]: Betampona R. N. I ., piste principale à 4 km via piste de Betakonana, 17 °55'55"S 49°12'11"E, 500 m, XI–XII.1998, fl., Rabenantoandro et al. 59 (MO-5167753!; iso-: P [ P00516015 ]!) .

Affine Memecyloni subsessili H. Perrier, sed ab eo foliis perfecte sessilibus (non breviter petiolatis petiolis 1–2 mm longis), laminis foliaribus brevioribus plerumque 5–9 × 1.5–3 cm ad basin cordatis amplexicaulibusque (non 7.5–19 × 2–3 cm ad basin cordatis non amplexicaulibus), cymis 1- ad 3- (non 3- ad 9-) floris, bracteis deciduis (non persistentibus), antheris 3 mm (non 2 mm) longis, antherae connectivo ad extremitatem fere subulatam (non breviter conicam) et septis interstaminalibus membranaceis (non vix evolutis) differt.

Shrubs 2 m high; branchlets terete (quadrangular on new growth but this is not continuing below the first internode); bark blackish brown on young branchlets, soon exfoliating in shreds or in shorter, rectangular patches; lower branchlets whitish; internodes mostly 1.5–3 cm long. Leaves subcoriaceous, quite sessile, slightly roughened on both surfaces when dry, fibrous when torn; blades lanceolate, 5–9(–10) × (1–) 1.5–3 cm, base strongly cordate and amplexicaul, apex acuminate-acute; midnerve slightly grooved on the upper surface, somewhat prominent on the lower; transverse veins perpendicular to the midnerve, ± invisible. Cymes axillary and at defoliated nodes, 0.5– 1 cm long, 1– 3(– 5)-flowered; peduncles (1.5 –)2– 3(– 6) mm long; bracts caducous, not seen. Flowers terminating each secondary axis, subsessile (true pedicels nearly absent); hypantho-calyx obconic, 3 × 3 mm, lobes scarcely developed, rounded; petals violet, ovate, 2.5–3 × 1.5 mm, acuminate-acute; anthers 3 mm long, dolabriform, the anther sacs situated fronto-ventrally; extremity of connective long and narrow, almost subulate; gland punctiform; epigynous chamber with membranous partitions; style 4 mm long (before anthesis). Fruits unknown.

Etymology. – The epithet draconopterum is a compound formed from the Greek nouns drákon meaning “dragon” and pterón meaning “wing”. It functions as an adjective and means “dragon-winged”, in reference to the shape of the leaves.

Distribution and ecology. – East-central Madagascar (Atsinanana region), known only from the type collection from the Réserve Naturelle Intégrale de Betampona, c. 31 km

2 mm

[A–E: Rabenantoandro et al. 59, MO, P] [Drawing: S. Burrows]

northwest of the coastal city of Toamasina. Habitat in remnant of lowland humid forest, elevation 500 m.

Conservation status. – Memecylon draconopterum is known from a single location (estimated AOO of 4 km ²) within the Betampona strict nature reserve (2,248 ha) managed by Madagascar National Parks. This area was formerly connected with the Ankeniheny-Zahamena corridor to the west, but deforestation in the vicinity of Toamasina (Tamatave) has left it as an isolated remnant of lowland forest surrounded by anthropogenic vegetation ( GOODMAN et al., 2021). Ongoing pressures include illegal cutting of trees for timber and construction, collection of non-timber forest products, and presence of invasive plant species ( GOODMAN et al., 2021). Based on its limited AOO and the apparent threats, M. draconopterum would meet the criterion B for listing as “Critically Endangered” in accordance with the IUCN Red List Categories and Criteria ( IUCN, 2012), but it might be better assessed as “Near Threatened” [NT], contingent on the continued effectiveness of habitat-specific conservation and management measures ( IUCN, 2019). The species is still poorly known, and we need better information on its local distribution and abundance.

Notes. – Memecylon draconopterum is closely related to M. subsessile H. Perrier , as evidenced by a suite of shared characters, such as the brownish-black, rapidly exfoliating bark of the younger branchlets, the narrow leaves that are cordate at base and acuminate-acute at the apex, and the presence of an anther-gland. Both of these species also inhabit the same region of east-central Madagascar. However, the new species is separated from M. subsessile by at least eight characters (see diagnosis, above), most notably by its shorter, completely sessile leaves with bases broadly cordate-amplexicaul (vs. cordate but distinctly short-petiolate and not clasping). The posterior extremity of the connective in M. draconopterum is remarkably long and narrow (vs. shortly conical-acute in. M. subsessile ).

Figures

Fig. 3. – Memecylon draconopterum R.D. Stone. A. Flowering branch; B. Section of branchlet showing exfoliating character of bark; C. Floral bud; D. Petal; E. Stamen.