Noronhia coriacea

Hong-Wa, Cynthia, 2016, A taxonomic revision of the genus Noronhia Stadtm. ex Thouars (Oleaceae) in Madagascar and the Comoro Islands, Boissiera 70, pp. 1-292 : 78

17. Noronhia coriacea Hong-Wa, spec. nova ( Fig. 11 ).

Typus: MADAGASCAR. Prov. Toliara: Anosy, Andohahela (parcel 3), Ankazofotsy , 25°01’S 46°38’E, 15.V.2001, Randriamampionona 1004 (holo-: MO-6615574!; iso-: BR!, G [ G00341630 ]!, K!, MO-6616000!, P [ P03533041 ]!, TAN!, US!, WAG!) .

Diagnosis

Noronhia coriacea Hong-Wa can be distinguished from other members of the genus by its white bark, its thick, coriaceous, shiny leaf blades and its ovoid and smooth fruits.

Description

Trees to 6 m tall; young twigs flattened, 1.3-1.5 mm diameter, glabrous; bark whitish, smooth to rugose. Leaves opposite, persistent; bud scales rarely persistent; blades glossy green almost silvery above, dull green to yellowish below, oblanceolate to obovate, 6.5-9 3 1.8-2.2 cm, coriaceous, glabrous, domatia absent, base acute to attenuate, margin slightly revolute, apex retuse to rounded, midrib slightly sunken above, distinctly raised above, secondary veins inconspicuous, 9-11 per side, 7-10 mm apart, looping 1-2 mm from the margin; petiole whitish, 6-9 3 1.5-1.7 mm, entirely woody, glabrous. Flowers unseen, but infructescence thyrsoid. Fruiting pedicel 5-7 3 0.9-1.3 mm; young fruits green, unseen mature, ovoid, 11.5-11.8 3 9-10 mm, smooth, apex flat to bluntly pointed, ridged, style persistent; dry pericarp 1.2- 1.5 mm thick; endocarp woody; seed 7-7.5 3 4-4.5 mm.

Distribution, ecology and phenology

Noronhia coriacea occurs in low elevation transitional forest on basement rocks at Andohahela in the south ( Fig. 9 ). It has been collected in fruits in May.

Conservation status

With just a single collection known from a restricted forest (Andohahela Parcel 3), N. coriacea has an AOO of just 4 km 2 and one subpopulation, representing a single location. Despite its occurrence within a protected area (Andohahela), which theoretically provides protection, this species may nonetheless experience a decline in habitat quality in the near future due to the close proximity of the subpopulation to a national road (less than 100 m away), where forest clearance can be observed. Therefore, N. coriacea is assigned a preliminary status of “Vulnerable” [VU D2].

Notes

Noronhia coriacea is somewhat similar to N. retusifolia Hong-Wa, but can be distinguished by having only opposite leaves (vs. opposite to verticillate at the tips of the branches), by the absence (vs. presence) of domatia on the abaxial surface of the leaf blades, and by having smooth (vs. rugose) fruits. The new species can be recognized by its white bark, thick, coriaceous, shiny leaf blades, and ovoid and smooth fruits.

Figures

Fig. 11. Noronhia coriacea Hong-Wa.

Fig. 9. Distribution maps of species of Noronhia Stadtm.ex Thouars. N. christenseniana Dubard to N. domatifera Bosser.