Noronhia stevensiana

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 : 254-256

79. Noronhia stevensiana Hong-Wa, spec. nova ( Fig. 64, 65A ).

Typus: MADAGASCAR. Prov. Antsiranana: DIANA , Diégo II , Antsalaka, Montagne d’Ambre AP, 12°37’17”S 49°10’46”E, 1038 m, 12. VI .2010, Hong-Wa 711 (holo-: MO-6615564!; iso-: P!, TAN!).

Diagnosis

Noronhia stevensiana Hong-Wa can be distinguished from other members of the genus by its partially woody petioles, its chartaceous and lanceolate leaf blades, its somewhat compact inflorescences, with cupuliform, cream-white pinkish flowers, and its crustaceous, subglobose fruits without a distinct apex.

Description

Trees to 14 m tall, trunk to 20 cm diameter; young twigs flattened to cylindrical, 0.5-2 mm diameter, glabrous; bark dark gray, smooth to rugose. Leaves opposite, persistent; bud scales deciduous; blades medium green above, lighter below, lanceolate to oblong, 6-14 3 1.5-4 cm, chartaceous, glabrous, domatia absent, base acute, margin flat to slightly undulate, apex acuminate, the acumen 5-22 mm long, midrib flat to slightly sunken above, raised below, secondary veins conspicuous, 8-15 per side, 6-16 mm apart, looping 1.5-4 mm from the margin; petiole medium gray, 4-12 3 1-1.7 mm, partially woody, glabrous. Thyrses solitary to geminate, pauciflorous, compact to somewhat diffuse; peduncle 5-10 mm long, moderately pubescent; pedicel 2-5 mm long, moderately pubescent; calyx moderately pubescent outside, glabrous inside, lobes triangular, 0.8-1.5 3 1-2 mm; corolla pink fading to white cream tinged pink, cupuliform, 2.5-3.5 mm long, glabrous on both sides, the tube 1.3-2.5 mm long, lobes widely ovate, apex obtuse; corona present, 1-1.5 mm long, undivided; stamens 1.5-1.7 mm long, anthers obovate, 1-1.1 mm long; pistil 1.3-2.2 mm long, stigma capitate. Fruiting pedicel 4-5 3 1.6-1.8 mm; young fruits green, purplish black when mature, subglobose to ovoid, 17.5-21 3 14.5-19 mm, surface smooth to rugose, sometimes covered with a white pellicle, apex flat; dry pericarp 0.7-0.8 mm thick; endocarp crustaceous; seed 19 3 8.5 mm.

Etymology

This name honors Peter F. Stevens for his contribution to the knowledge of the Malagasy flora, for his invaluable mentorship, and for sharing his passion for plants.

Distribution, ecology and phenology

Noronhia stevensiana occurs in mid- to high-elevation humid forests on lavas on the Montagne d’Ambre in the north ( Fig. 62 ). It produces flowers and fruits from January to June.

Conservation status

Noronhia stevensiana is currently known only from nine collections representing seven localities. With an EOO of 33 km 2, an AOO of 24 km 2, and three subpopulations representing three locations, all included within Montagne d’Ambre PN, which is still sub-ject to continuing decline in habitat quality and loss of mature individuals as a result of illicit exploitation and encroachment for crop and khat cultivation, N. stevensiana is assigned a preliminary status of “Endangered” [EN B1ab(iii,v)+2ab(iii,v)].

256 Boissiera 70

Notes

Noronhia stevensiana resembles N. schatzii , but these two taxa can be distinguished by the texture of their petioles, the density of their inflorescences, the pubescence of their peduncles and pedicels, and the shape of their fruits. Identifying features include partially woody petioles, chartaceous and lanceolate leaf blades, somewhat compact inflorescences, with cupuliform, cream-white pinkish flowers, and crustaceous, subglobose fruits without a distinct apex.

Paratypi

MADAGASCAR. Prov. Antsiranana: Joffreville, Montagne d’Ambre PN , 12°32’19”S 49°09’32”E, 1219 m, 23. I .2009, Hong-Wa 577 ( MO, P, TAN); ibid. loc., Hong-Wa 578 ( MO, P, TAN); ibid. loc., Hong-Wa 580 ( MO, P, TAN); ibid. loc ., 12°30’55”S 49°10’34”E, 891 m, 24. I .2009, Hong-Wa 590 ( MO, P, TAN); ibid. loc ., 12°30’56”S 49°10’40”E, 931 m, 16. V .2010, Hong-Wa & Ortiz 680 ( MO, P, TAN); ibid. loc ., 12°32’35”S 49°08’46”E, 1315 m, 17. V .2010, Hong-Wa & Ortiz 685 ( MO, TAN); ibid. loc ., 12°36’17”S 49°11’22”E, 1035 m, 9. V .2008, Trigui et al. 383 ( G, MO, TEF); ibid. loc ., 12°37’48”S 49°10’44”E, 1030 m, 16. VI .2008, Trigui et al. 543 ( G, MO, TEF) .

Figures

Fig.65.Photographs of Noronhia Stadtm.ex Thouars.

Fig. 62. Distribution maps of species of Noronhia Stadtm. ex Thouars.N. similis Hong-Wa to N. tubulosa H. Perrier.