Diospyros hongwae G.E. Schatz, Lowry & Phillipson, 2020

Schatz, George E., Lowry Ii, Porter P. & Phillipson, Peter B., 2020, Taxonomic studies of Diospyros (Ebenaceae) from the Malagasy region. V. Synoptic revision of the Bernieriana group in Madagascar and the Comoro Islands, Candollea 75 (2), pp. 203-218 : 208-210

3. Diospyros hongwae G.E. Schatz, Lowry & Phillipson , sp. nov.

( Fig. 1B–D , 2 ).

Holotypus: MADAGASCAR. Reg. DIANA [Prov. Antsiranana]: env. d’Iraro ( vallée de l’Ifasy ), [13°24'S 48°55'E], 50 m, IV.1951 [31.III.1951], ♀ fl., fr., Service Forestier 3075 ( P [ P03975005 ]!; iso-: MO-6956006 !, G [ G00341733 ]!, P [ P00722702 ]!, TEF!, W!).

Diospyros hongwae G.E. Schatz, Lowry & Phillipson can be distinguished from other members of the Bernieriana group by its large lamina (to 12 × 4.9 cm) with a flat margin and subspherical fruit slightly exserted above the cupuliform calyx, i.e., the apex of the fruit visible.

Shrub to tree 4– 15 m tall. Young stems initially sparsely to moderately densely covered with appressed, very short (<0.1 mm) gray trichomes, glabrescent. Leaves 4–12 × 1.4–4.9 cm, elliptic, glabrous above and below, glossy above, base acute to cuneate, margin flat (weakly undulate in fresh material), apex acuminate, the acumen to 11 mm, rounded, midrib slightly impressed above, raise below, venation weakly brochidodromous with 8–10 secondary veins per side, flat to slightly raised above and below, faintly visible, tertiary venation indistinct; petiole 7–11 mm, 1 mm diam., canaliculate, initially sparsely to moderately densely covered with appressed, very short (<0.1 mm) gray trichomes glabrescent. Male flowers not seen. Female flowers solitary in the axils of leaves and fallen leaves; pedicel 2–3 mm long, 2–3 mm diam., bearing several bracts (based upon bract scars), densely covered with very short, erect, light golden to gray trichomes; flowers ellipsoid at anthesis, calyx fully fused, adnate to the receptacle, the apex entire, 7–8 mm long, 6 mm in diam., glabrous outside, densely covered with very short, erect light golden to gray trichomes inside; calyx rapidly expanding post anthesis, extending an additional 4 mm, cupuliform; corolla tubular, 15 mm long, 4 mm in diam., lobes 4, ovate, 5 × 4 mm, apex acute, adaxially concave, densely covered with very short, appressed trichomes outside, glabrous inside; staminodia c. 18, inserted at base of corolla tube, filaments 3 mm, the distal 1 mm free, antherodes 1.5 mm, ovary subspherical, crowned by conical style, the stigma 4-lobed, lobes 1.5 mm long. Pedicel in fruit expanding to 4– 5 mm in diam., with a distinct apical rim to 6 mm in diam., the apex convex. Receptacle in fruit to 3 mm thick at base. Fruit subspherical, the apex slightly exserted above the prolonged cupuliform calyx, i.e., visible, c. 10–12 mm in diam., densely covered with short (c. 0.5 mm), appressed, light golden trichomes, crowned by the style/stigma remnant, cone-shaped, 2– 4 mm tall, 2 mm in diam. at base, densely covered with shorter (c. 0.2 mm) semi-appressed darker golden trichomes.

Etymology. – The species epithet honors our colleague and good friend Cynthia Hong-Wa, who brought order to the large and complex genus Noronhia Stadtm. ex Thouars (Oleaceae) .

Vernacular name. – “Ambavy” (Hong-Wa 317).

Distribution and ecology. – Diospyros hongwae is known from only three gatherings in dry forest on sandstone and alluvial soils along rivers south of Ambanja ( MADAGASCAR CATALOGUE, 2020), at an elevation of 50– 236 m.

Conservation status. – Diospyros hongwae has a restricted geographic range in the form of an EOO and AOO of 0.263 km ². It is not known from within any protected area, and is threatened by forest clearing for agriculture, grazing, fire, and exploitation for firewood and construction material, all of which are projected to result in continuing decline. With respect to the principal threat of forest clearing for agriculture, it exists at two locations. Therefore, D. hongwae can be assessed for its risk of extinction as “Endangered” [EN B1ab(i,ii,iii,iv, v)+2ab(i,ii,iii,iv,v)].

Notes. – The collections Humbert & Capuron 25932 and Service Forestier 3075 represent a single gathering divided between two separate collection series. Diospyros hongwae can be distinguished from other members of the Bernieriana group by its large leaves with flat margins (weakly undulate in fresh material) and its subspherical fruit, the apex of which is slightly exserted above the prolonged cupuliform calyx and thus visible.

Paratypi. – MADAGASCAR. Reg. DIANA [Prov. Antsiranana]: Ambakirano, Behefaka , Anjahana , 13°20'55"S 49°10'45"E, 236 m, 7.VI.2005, fr., Hong-Wa 317 ( MO, P); ibid. loco, 13.XII.2018, fr., Randrianaivo et al. 3298 ( MO, P, TAN); vallée de l’Ifasy , en aval d’Anaborano , grès et alluvions, [13°24'S 48°55'E], 50–200 m, 31.III.1951, ♀ fl., fr., Humbert & Capuron 25932 ( G, MO, P [2 sheets]).

Figures

Fig. 1. – Diospyros bernieriana (Baill.) H. Perrier: A. Immature fruits with developing calyx. D. hongwae G.E. Schatz, Lowry & Phillipson: B–D. Nearly mature fruits with expanding calyx. [A: Schatz et al. 4342; B–D: Hong-Wa 317] [Photos: A: G.E. Schatz; B–D: C. Hong-Wa]

Fig. 2. – Diospyros hongwae G.E. Schatz, Lowry & Phillipson. A. Fruiting branch; B. Detail of leaf venation (adaxial surface); C. Fruit; D. Female flower prior to anthesis; E. Schematic drawing of female flower with a portion of the calyx removed. [A–E: Hong-Wa 317, P] [Drawing: Alain Jouy]