Homalium acuminatifolium Appleq., 2018

Applequist, Wendy L., 2018, A revision of the Malagasy species of Homalium sect. Blackwellia (Salicaceae), Candollea 73 (2), pp. 221-244 : 225

1. Homalium acuminatifolium Appleq. , spec. nova ( Fig. 1 ).

Holotypus: MADAGASCAR. Prov. Toliara: forêt au S d’Eminiminy , Parcelle I dans la RNI d’Andohahela , 24°39'00"S 46°48'30"E, 0 – 500 m, 10 – 26.XI.1993, fl., Randriamampionona 682 ( MO-6087923!; isotype: MO-6087899 !, P [ P04735190 ]!, TAN) .

Homalium acuminatifolium Appleq. differs from H. axillare (Lam.) Benth. in having lanceolate (to narrowly lanceolate or ovate), acuminate leaves.

Tree to 15 m, 30 cm dbh; young twigs glabrous. Leaves lanceolate to narrowly lanceolate (ovate), 4–7.3 × (1.1–)1.3 –2.1(–3) cm; petiole 3– 8 mm; base convex (rounded); apex long-acuminate; margins shallowly serrate, with glands small, usually protruding at apex of tooth; adaxial surface drying grayish to blackish, greenish or darker brown, abaxial surface pale brown to brown. Inflorescences racemose, lateral, (2 –) 4 – 10 cm, short-pubescent; flowers pedicellate with pedicels (0.3–)0.5 – 1.4(– 2.3) mm; bracts broadly elliptical to broadly ovate, 0.4– 1 mm. Flowers 9-merous; calyx tube short with a rounded base, sparsely pubescent; sepals ligulate with acute apex, 1.3–2.3 mm; petals ligulate with acute apex, 1.4– 2.3 mm; sepals and petals yellowish-white, probably somewhat accrescent, usually much longer than calyx tube, often spreading and often becoming somewhat reflexed after flowering, densely ciliate with long trichomes, both surfaces sparsely pubescent or adaxial surface sparsely hispid; sepal glands glabrous; filaments 1.7–2.6 mm, sparsely pubescent; ovary densely hispid to pilose; styles 4–5, 1.3–2 mm, basally hispid to pilose.

Vernacular names. – “Hazofotsy” (Réserves Naturelles 2098); “Zôra” (Randriamampionona 682, Réserves Naturelles 2098, 6733).

Distribution, ecology and conservation status. – Homalium acuminatifolium is native to low- to mid-elevation humid forests in the southeastern part of the province of Toliara; it sometimes occurs along waterways and on laterite and granite. GeoCAT estimates the Extent of Occurrence at c. 791 km ² and the Area of Occupancy at 28 km ²; there are seven distinct locations, though four of these are within a few km of one another. The species does occur in the protected area of Andohahela, but its habitat outside Andohahela is threatened with continuing degradation. Therefore a conservation status of “Vulnerable” [VU B1ab(iii)+B2ab(iii)] would seem to be warranted.

Note. – Sleumer determined available specimens of this taxon as H. axillare (Lam.) Benth. “ forma foliis ovato-lanceol.” The flowers resemble those of H. axillare but the leaves are distinctly different in shape, being usually lanceolate (to narrowly lanceolate or ovate) with a long-acuminate apex. Leaf margins are shallowly serrate and the small marginal glands usually protrude from tooth apices. The racemes are sometimes very numerous and crowded and the petals and sepals are more commonly spreading at anthesis, though these characters are variable.

Paratypi. – MADAGASCAR. Prov. Toliara: à la base et en avant de la forêt de Manantantely près de Fort-Dauphin , 50–300 m, 1.III.1947, fl., Humbert 20373 ( P) ; Farafara Vatanibe, W du village de Malamba , au bord de la Belomotse , 24°51'02"S 47°00'20"E, 135 m, 14–18.XI.2009, post-fl., Rakotovao et al. 4517 ( MO) ; SW de la forêt d’Ankiboriabo , Marovato , parcelle I d’Andohahela RNI , 24°36'S 46°50'E, 250–750 m, 14.XI.1993, fl. & fr., Randriamampionona 659 ( BM, BR, CANB, CAS, G, K, L, M, MO, P, PRE, S, US, USMS) ; Magatisaka, 24°35'07"S 47°02'15"E, 669 m, 21.XI.2009, fl., Razakamalala 4774 ( MO) ; Ifarantsa , Fahibe , 11.XII.1950, fl. & fr., Réserves Naturelles 2098 ( P) ; FortDauphin , Naniliha [ Enaniliha ], 15.IX.1954, Réserves Naturelles 6733 ( P) .

Figures

Fig. 1. – Homalium acuminatifolium Appleq. A. Flowering branch; B. Flowers. [Randriamampionona 682, TAN] [Drawing: R.L. Andriamiarisoa]