Noronhia dauphinensis

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 : 88-90

21. Noronhia dauphinensis Hong-Wa, spec. nova ( Fig. 14 ).

Typus: MADAGASCAR. Prov. Toliara: Anosy, Fort-Dauphin , Iaboko , Antsotso , forêt Ivohibe , 24°33’52”S 47°14’25’’E, 112 m, 26.XI.2005, Razakamalala et al. 2380 (holo-: MO-6615557!; iso-: G [ G00341620 ]!, P [ P06490461 ]!, TAN!) .

Diagnosis

Noronhia dauphinensis Hong-Wa can be distinguished from other congeneric species by its distichous, oblong to elliptic leaf blades subtended by a short petiole and its compact inflorescences.

Description

Small trees to 8 m tall, trunk to 8 cm diameter; young twigs cylindrical to somewhat flattened, 1.2-1.7 mm diameter, glabrous; bark medium gray to brownish, smooth. Leaves opposite, persistent; bud scales deciduous; blades dark green above, lighter below, oblong to elliptic or lanceolate, 6-12.5 3 2.5-7 cm, coriaceous, glabrous, domatia absent, base rounded to acute, margin slightly revolute, apex acuminate, the acumen 3-7 mm long, midrib sunken above, raised below, secondary veins conspicuous, 8-12 per side, 10-20 mm apart, looping 1.5-4 mm from the margin; petiole medium gray to brownish, 2-7 3 1.5-3 mm, entirely woody, glabrous. Thyrses geminate, multiflorous, compact; peduncle 1-3 mm long, moderately pubescent; pedicel 1.5-3 mm long, moderately pubescent; calyx sparsely pubescent outside, glabrous inside, lobes triangular, 0.7-1 3 0.9-1.4 mm; corolla white, cupuliform, 3.5-4.2 mm long, glabrous on both sides, the tube 1.5-3 mm long, lobes oblong, apex obtuse; corona present, 1.2-1.5 mm long, undivided; stamens 1.2-1.7 mm long, anthers oblong, 0.9- 1.2 mm long; pistil 1.3-1.8 mm long, stigma slightly bilobed. Fruiting pedicel 5-6 3 1-1.2 mm; young fruits green, dark brownish when mature, ovoid, 8.5-10 3 6.5-7.5 mm, surface smooth, apex flat, with the persistent style; dry pericarp 0.4 mm thick; endocarp woody.

Etymology

This species is known only from the region of Fort-Dauphin, from which the epithet “dauphinensis” is derived.

Distribution, ecology and phenology

Noronhia dauphinensis occurs in low-elevation humid forests on basement rocks north of Fort-Dauphin in the south ( Fig. 9 ). It produces flowers and fruits from November to May.

Conservation status

The assessment was based on six collections representing five localities and yielded an EOO of just 7 km 2 and two subpopulations representing a single location (Bemangidy-Ivohibe forest). Some of the collections are encompassed within the newly established protected area of Tsitongambarika (including Bemangidy-Ivohibe), which will gradually be less subject to threats. However, others are found outside of the new protected area and will likely experience continuing decline in habitat quality and in the number of mature individuals resulting from forest exploitation. Thus, N. dauphinensis is assigned a preliminary status of “Endangered” [EN B2ab(iii,v)].

90 Boissiera 70

Notes

Noronhia dauphinensis most closely resembles N. boivinii , from which it differs mainly by its thyrsoid inflorescences (vs. fasciculate flowers), cupuliform (vs. urceolate to campanulate), white (vs. pink to reddish) corolla, and bilobed (vs. capitate) stigma. The new species can be recognized by its distichous, oblong to elliptic leaf blades subtended by a short petiole and its compact inflorescences.

Paratypi

MADAGASCAR. Prov. Toliara: Fort-Dauphin, Bemangidy Forest , 24°34’05”S 47°12’38”E, 100 m, 10. II .2006, Lowry et al. 6741 ( G, MO, P); Iabakoho, Antsotso Avaratra, Ivohibe , 24°34’10”S 47°12’26”E, 105 m, 24. V .2006, Birkinshaw 1642 ( MO, P, TAN); ibid. loc ., 24°35’33”S 47°12’52”E, 22. V .2006, Rajoharison et al. 156 ( MO, P, TEF); ibid. loc ., 24°33’52”S 47°11’43”E, 386 m, 1.XI.2005, Razakamalala et al. 2463 ( G, MO, P, TAN); ibid. loc., Razakamalala et al. 2551 ( MO, P, TAN) .

Figures

Fig. 14. Noronhia dauphinensis Hong-Wa.

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