New species of Memecylon (Melastomataceae) from Madagascar: treasures of the TEF Herbarium
Stone, Robert Douglas
Candollea
2020
2020-10-29
75
2
219
239
7X8HV
R.D. Stone
R. D. Stone
2020
[801,1210,1484,1508]
Magnoliopsida
Melastomataceae
Memecylon
Plantae
Myrtales
15
234
Tracheophyta
species
subchartaceum
sp. nov.
Holotypus: MADAGASCAR. Reg. Anosy [Prov. Toliara]: forêt de Lakandava(station Jirama), 25.I.1990, fr., Rabevohitra2207(CAS-844951!; iso-: MO-3778128!, P[ P05207253]!, TEF!).
Ob florem ignotum affinitatis incertae, Memecylon sabuloso Jacq.-Fél. et M. ivohibensi Jacq.-Fél. similis, sed ab eis laminae foliaris textura in sicco insolenter tenui fere papyracea bene distincta. Evergreen shrubor tree 3– 7 mhigh; young branchlets very slender, sometimes wiry, subquadrangular to terete; older branchlets somewhat thickened at the nodes, blackish brown; internodes 0.5–2.0(–4.7) cm long, with intervening “aphyllous” nodes sometimes also present. Leavesthin, subchartaceous in dried material, bright green on the adaxial surface, slightly paler abaxially; petioles ± yellow, 0.5–2(–3) mm long; blades lanceolate to narrowly elliptic, (1.8–)2.7–5(–6.8) × (0.5–)0.7–1.2 (–1.9) cm, base narrowly cuneate, apex acute or ± acuminate, the acumen (4–)6–12(–18) mm; only the midnerve clearly visible, ± yellow, subprominent on adaxial and especially abaxial surfaces towards the base of the blade; intramarginal nerves very thin, faintly visible, ± prominent on both surfaces; transverse veins ± obscure or subprominent like the intramarginal nerves, oriented at an oblique angle relative to the midnerve. Flowersnot seen. Fruitsgreen, globose, about the size of a large pea; calycinal crown very short and somewhat membranous in texture; calyx margin 4-microdentate; epigynous chamber shallow; top of ovary nearly smooth (radial partitions very faint).
Etymology. – The adjectival epithet subchartaceumis in reference to the leaves of this species which are unusually thin-textured, almost papery.
Distribution and ecology. – Known from two localities in the Anosy region of southeastern Madagascar, just inland from the coastal city of Tôlan¨ aro (Fort-Dauphin) ( Fig. 2). Habitat in humid forest below 300 melevation.
Conservation status. – Memecylon subchartaceumhas an EOO of 56 km² and an estimated AOO of 12 km² (assuming a 4 km² grid cell size). The known subpopulations in the Lakandava and Bemangidy-Ivohibe forests are both presumably threatened by shifting agriculture (tavy), although the latter site may receive some degree of protection under a conservation agreement between the IUCN and the Rio Tinto mining company. Memecylon subchartaceumis thus provisionally assessed as “Endangered” [EN B2ab(iii)] in accordance with the IUCN Red List Categories and Criteria ( IUCN, 2012).
Notes. – The flowers of M. subchartaceumare still unknown, and its affinity remains uncertain. It has been confused with M. sabulosumJacq.-Fél., which occurs in the same vicinity and has leaves of a similar shape and size (narrowly lanceolate with dimensions 4.5 × 1.2 cmper description). However, in M. sabulosumthe leaf-blades are dark green and ± rigidly coriaceous while in M. subchartaceumthey are a paler green and unusually thin-textured. Memecylon ivohibenseJacq.-Fél. is also similar but in material of that species the leaves although narrowly lanceolate are smaller (dimensions 3 × 0.6 cm). In comparison to the collections of M. subchartaceumfrom its typelocality near Tôlan¨ aro (Fort-Dauphin), the material from Iabakoho notably differs in having somewhat longer internodes and larger leaves.
Paratypi. – MADAGASCAR. Reg. Anosy [Prov.Toliara]: Lakandava forest, 24°58'S 46°58'E, 25.I.1990, y.fr., McPhersonet al. 14893(CAS, K, MO, P, TEF); Iabakoho, Antsotso Avaratra, Ivohibe, 24°34'17"S 47°12' 07"E, 21.V.2006, fr., Birkinshawet al. 1614( CAS, MO, P, TAN); village d’Antsotso Avaratra, forêt de Bemangidy, 24°35' 33"S 47°12'52"E, 22.V.2006, fr., Randriatafikaet al. 656( CAS, NU, P).
3407891305
1990-01-25
I
de Lakandava
Madagascar
foret de Lakandava
15
234
P05207253
1
Reg. Anosy [Prov. Toliara
holotype
3407891310
1990-01-25
K, MO, P, TEF
McPherson
Madagascar
-24.966667
Lakandava forest
1249
46.966667
17
236
1
Reg. Anosy [Prov. Toliara
paratype
3407891316
2006-05-21
CAS, MO, P, TAN
Birkinshaw
-24.57139
Antsotso Avaratra
21
47.201946
Iabakoho
17
236
1
3407891315
2006-05-22
CAS, NU, P
Randriatafika
-24.5925
village d'Antsotso Avaratra
21
47.214447
17
236
1