Memecylon subchartaceum R.D. Stone, 2020

Stone, Robert Douglas, 2020, New species of Memecylon (Melastomataceae) from Madagascar: treasures of the TEF Herbarium, Candollea 75 (2), pp. 219-239 : 234-236

publication ID

https://doi.org/ 10.15553/c2020v752a6

DOI

https://doi.org/10.5281/zenodo.5708764

persistent identifier

https://treatment.plazi.org/id/039D905A-FF83-F616-DF05-7C8B77F8FEDE

treatment provided by

Carolina

scientific name

Memecylon subchartaceum R.D. Stone
status

sp. nov.

Memecylon subchartaceum R.D. Stone   , sp. nov. ( Fig. 9 View Fig ).

Holotypus: MADAGASCAR. Reg. Anosy [Prov. Toliara]: forêt de Lakandava (station Jirama), 25.I.1990, fr., Rabevohitra 2207 (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 shrub or tree 3– 7 m high; 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. Leaves thin, 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. Flowers not seen. Fruits green, 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).

[ A – B, E: Rabevohitra 2207, CAS; C: McPherson et al. 14893, CAS; D: Birkinshaw et al. 1614, MO] [Drawing: S. Burrows]

Etymology. – The adjectival epithet subchartaceum   is 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 View Fig ). Habitat in humid forest below 300 m elevation.

Conservation status. – Memecylon subchartaceum   has an EOO of 56 km ² and an estimated AOO of 12 km ² (assuming a 4 km ² 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 subchartaceum   is thus provisionally assessed as “Endangered” [EN B 2ab(iii)] in accordance with the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – The flowers of M. subchartaceum   are still unknown, and its affinity remains uncertain. It has been confused with M. sabulosum Jacq.   -Fél., which occurs in the same vicinity and has leaves of a similar shape and size (narrowly lanceolate with dimensions 4.5 × 1.2 cm per description). However, in M. sabulosum   the leaf-blades are dark green and ± rigidly coriaceous while in M. subchartaceum   they are a paler green and unusually thin-textured. Memecylon ivohibense Jacq.   -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. subchartaceum   from its type locality 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., McPherson et al. 14893 (CAS, K, MO, P, TEF); GoogleMaps  

Iabakoho, Antsotso Avaratra , Ivohibe , 24°34'17"S 47°12'07"E, 21.V.2006, fr., Birkinshaw et al. 1614 ( CAS, MO, P, TAN); GoogleMaps   village d’Antsotso Avaratra , forêt de Bemangidy , 24°35'33"S 47°12'52"E, 22.V.2006, fr., Randriatafika et al. 656 ( CAS, NU, P). GoogleMaps  

TEF

TEF

CAS

USA, California, San Francisco, California Academy of Sciences

P

Museum National d' Histoire Naturelle, Paris (MNHN) - Vascular Plants

TEF

Centre National de la Recherche Appliquée au Developement Rural

A

Harvard University - Arnold Arboretum

B

Botanischer Garten und Botanisches Museum Berlin-Dahlem, Zentraleinrichtung der Freien Universitaet

E

Royal Botanic Garden Edinburgh

MO

Missouri Botanical Garden

S

Department of Botany, Swedish Museum of Natural History

K

Royal Botanic Gardens

TAN

Parc de Tsimbazaza

NU

Department of Microbiology, Faculty of Science