Memecylon buxifolium Blume

4. Memecylon buxifolium Blume in Mus. Bot. 1: 363. 1851.

Lectotypus (designated by JACQUES- F ÉLIX, 1985b: 31): MADAGASCAR. Reg. DIANA [Prov. Antsiranana]: île de Nossibé [Nosy Be], 4.XI.1840, ster., Pervillé 344 (L [L.2543432]!; isolecto-: BR [BR0000006260873]), K [K000313579]!, P [P00057733, P00057734, P00057735]!).

Memecylon dumosum Naudin in Ann. Sci. Nat., Bot., sér. 3, 18: 270. 1852 [nom. illeg.].

= Memecylon perrieri Danguy in Compt. Rend. Assoc. F ranç. Avancem. Sci. Assoc. Sci. F rance [45E session, Rouen 1921]: 545. 1922. Holotypus: MADAGASCAR. Reg. Betsiboka [Prov. Mahajanga]: Belambo, III.1900, fl., Perrier de la Bâthie 1048 (P [P00062681]!; iso-: P [P00062682]!).

Shrubs or small trees 1 – 5 m high; branchlets slender, quadrangular when young, becoming terete with age; successive nodes alternately bearing normal leaves and floral bracts (these c. 3 mm long, lance-linear, rapidly deciduous); internodes between normal leaves (0.8 –)1.1 –2.5(–5.8) cm long. Leaves coriaceous, bright green and shining on the upper surface, paler and dull on the lower, drying brownish and minutely granular-roughened on both surfaces; petioles 1 –3(–4) mm long; blades elliptic to elliptic-lanceolate, (2–) 2.5–4(–5.7) × (0.7–)1–1.6(–2.2) cm, mostly 2–3 times longer than broad, cuneate at base, generally acute at apex but sometimes obtuse-apiculate or vaguely acuminate-obtuse; only the midnerve clearly visible, finely impressed on the upper surface, somewhat prominent on the lower; one pair of lateral nerves faintly visible on both surfaces (especially in larger leaves and in fresh material), the course curvilinear and 1 – 2 mm from the margin in the basal half of the blade; transverse veins ± obscure. Cymules up to 1(–1.5) cm long, 1 – 2(– 3)-flowered, borne in the leaf axils and at the intervening “aphyllous” nodes; peduncles 0.5 – 6 mm long; secondary axes 0.5–4 mm long; bracts deltoid, c. 1 mm long, soon deciduous. Flowers on pedicels 0.5– 1(– 2) mm long; hypantho-calyx green, campanulate, 2 × 2.5 mm, margin sinuate; corolla rounded in bud; petals white, suborbicular, 2 × 2 mm, base broadly short-unguiculate; staminal filaments slender, 3 mm long; anthers 1.2 mm long, connective dorsally incurved by the median gland, thecae positioned at the anterior end, extremity obtuse; style 5–7 mm long; ovary 8–10-ovuled. Fruits ellipsoid, 7–10(–11) × 5–6 mm; calycinal crown spreading, 1 mm long; epigynous chamber with partitions joined in pairs to form V-shaped structures beneath the petal scars, each then joined to the center by a line.

Distribution and ecology. – Western Madagascar, in scattered locations from the extreme north (DIANA region) southward through the Sofia, Boeny, Betsiboka, and Melaky regions to near Morondava (Menabe region). Habitat in dry, deciduous forest, on various substrates, or in littoral forest or thicket on sands, at low elevations c. 0– 250 m.

Conservation status. – Memecylon buxifolium is known from 30 locations with an estimated EOO of 115, 436 km ² and an AOO of 120 km ². Roughly half of the known locations are in protected areas including the Réserve Spéciale d’Ankarana, the Paysage Harmonieux Protégé de Beanka, the Parc National de Tsingy de Bemaraha, and the Paysage Harmonieux Protégé de Menabe Antimena (GOODMAN et al., 2018). Dry forests in western Madagascar have been reduced by almost 40 % since the 1970s, and the rate of deforestation between the years 2000 and 2005 was 0.42 % per year (WAEBER et al., 2015, and references cited therein). Dry forests in unprotected areas are under pressure from clearing for subsistence and commercial agriculture, collecting of firewood and charcoal production, grazing of zebu cattle, and mining or oil exploration (WAEBER et al., 2015). Among the protected areas, there has been an acute loss of dry forest cover in Menabe Antimena (18,637 ha or 22.7 % between the years 2006 and 2016; GOODMAN et al., 2018). Anthropogenic fires have increased in recent years in both Menabe Antimena and Bemaraha (GOODMAN et al., 2018). Based on its limited AOO and the apparent threats, M. buxifolium would meet the criterion B for listing as “Endangered” [EN] in accordance with the IUCN Red List Categories and Criteria (IUCN, 2012), but it might be better assessed as “Near Threatened” [NT] contingent upon the continued effectiveness of habitat-specific conservation and management measures (IUCN, 2019).

Notes. – Memecylon buxifolium as presently circumscribed is the most common and widely distributed member of Memecylon sect. Buxifolia in Madagascar. It is also the most variable in terms of the size of the leaves. No specimens were cited in the protologue (BLUME, 1851), and the later statement by JACQUES- F ÉLIX (1985b: 31) that the holotype is in L is accepted here as an implicit lectotypification.

The type locality of Memecylon perrieri was given by PERRIER DE LA BÂTHIE (1951) as Belambo, rive gauche de l’Ikopa, en amont de Maevatanana (Boina). JACQUES- F ÉLIX (1985b) erroneously characterized the fruit of M. perrieri as globose, based on a specimen from the sand dunes at Ambongo (Pervillé 542, P) later excluded from that species (STONE, 2006b). JACQUES- F ÉLIX (1985b) also circumscribed M. buxifolium narrowly to include only the plants from Nosy Be. In comparing the original material of M. buxifolium and M. perrieri, one sees that the leaves of the latter are indeed larger, but with subsequent collections it is clear that both of these types are part of a ± continuous range of interpopulational variation (data not shown). In conclusion, there seems to be no objective basis for maintaining M. perrieri as a separate species.

Memecylon buxifolium includes most of the material previously assigned to M. ankarense H. Perrier (JACQUES- F ÉLIX, 1985b), but not the type of that species. STONE (2006b) made an error in stating that M. perrieri and M. ankarense were conspecific. Currently, M. ankarense is seen as more closely related to M. boinense H. Perrier (fide JACQUES- F ÉLIX, 1985b), the latter species belonging to the Malagasy clade sensu STONE (2014) and not a member of Memecylon sect. Buxifolia.

The collection Bernardi 11919 from Nosy Komba has floral bracts that are large and foliaceous (in fact having the appearance of small leaves, including a distinctly petiolar base). The same unusual feature is seen in some populations from the mainland of western Madagascar (e.g. Réserves Naturelles 10200, Stone 2644).

The following collections from the Oronjia protected area and the forêt de Belamoty (DIANA region near Antsiranana city) appear close to Memecylon buxifolium but have leaves obovate, mostly 1.7–2.3 × 1–1.6 cm (1.5–2 times longer than broad) and ± rounded at the apex. These populations remain unplaced to species pending further study: Rabenantoandro & Razanatsoa 624 (MO, P), Be et al. 78 (K, MO, NY, P), Ratovoson et al. 1150 (CAS, MO, P), Ratovoson et al. 2080 (MO).

Additional specimens examined. – Reg. DIANA [Prov. Antsiranana]: Nossi-bé [Nosy Be]- Tafondro, 15.XII.1967, fr., Bernardi 11905 (G, K, L, P); Nossi-Komba, 16.XII.1967, fl., Bernardi 11919 (K, L, P); Nossibé [Nosy Be], bord de la mer à Ampombilava, II–III.1851, fl. & fr., Boivin (P); Ankarana du Nord, I–II.1960, fr., Humbert 32555 (MO, P); forêt d’Ampiho, 2 km au N d’Ambodivahibe, 12°21'45"S 49°25' 50"E, 5 m, 24.VII.2007, fr., Ratovoson et al. 1304 (CAS, MO); Ambariobe (île déserte), N de Nosy-Komba, 09.V.1950, fr., Service Forestier 1231 (TE F); plateau de l’Ankarana, près d’Ambondromifehy, 05.II.1966, Service Forestier 24558 (G, K, MO, P, TE F, WAG); 5 km SE of Ambilobe on RN no 5A toward Ambakirano and Daraina, 13°12'00"S 49°04'45"E, 50 m, 11.II.2007, imm. fr., Stone et al.2636 (CAS, K, MO, P, TAN); RS de l’Ankarana, between Perte de Rivière and deviation toward Tourelles de Tsingy, 12°57'10"S 49°07'38"E, 150 m, 17.II.2007, ster., Stone et al. 2643 (CAS, MO, P, TAN); east of RN no 6 and N of Ambondromifehy, 12°52'13"S 49°13'46"E, 250 m, 18.II.2007, imm. fr., Stone et al. 2644 (CAS, K, MO, P, TAN). Reg. Sofia [Prov. Mahajanga]: Sofia, Antsohihy, Antonibe, Anjajavy, 15°02'27"S 47°15'43"E, 24 m, 17.VIII.2007, imm. fr., Rasoafaranaivo et al. 241 (MO, NU). Reg. Boeny [Prov. Mahajanga]: Manongarivo (Ambongo), X.1903, fl., Perrier de la Bâthie 6524 (P); dunes de Majunga, I.1921, fl., Perrier de la Bâthie 13457 (P); Ambato-Boina, Bevazaka, 12.II.1949, fl., Réserves Naturelles 1866 (MO, P). Reg. Betsiboka [Prov. Mahajanga]: Maevatanana, Mahatsinjo, Pont Betsiboka, 16°56'19"S 46°56' 52"E, 144 m, 08.VII.2005, fr., Hong-Wa et al. 404 (MO, NU, P); île de l’Ikopa, Ambodiroka, 1896, fr., Perrier de la Bâthie 32 (P); Mahajanga II, Cirque rouge, N of Amborovy, 15°38'04"S 46°20'28"E, 20 m, 20.III.2010, fr., Rakotonasolo et al. 1611 (BR, K); Maevatanana, Ambalanjanakomby, Ambatomitsangana, 19.XII.1953, fl., Service Forestier 8165 (TE F). Reg. Melaky [Prov. Mahajanga]: pents E du Bemaraha, VIII.1943, fr., Herb. Jard. Bot. Tananarive 6171 (P); Beanka forest, Bokarano, 17°54'41"S 44°28'37"E, 176 m, 23.X.2009, ster., Letsara et al. 906 (CAS); Beanka forest, Manomba, 17°52'90"S 44°29'15"E, 156 m, 24.X.2009, ster., Letsara et al. 909 (CAS, MO); Beanka forest, Kinahengo, 18°01'17"S 44°30'44"E, 225 m, 26.X.2009, fr., Letsara et al. 933 (CAS, NU); P.K. 5, route d’Antsalova, 13.VII.1970, fr., Rakotozafy 1028 (TAN); Antsalova, 8 km from Andranondahy, 18°47'42"S 44°47'26"E, 19.X.2006, fr., Ralimanana et al. 802 (K); Antsalova [= R.N.I. Bemaraha], 11.I.1959, fl., Réserves Naturelles 10200 (MO, P, TE F). Reg. Menabe [Prov. Toliara]: forêt de Marosalaza, 50 km au Nord de Morondava, 01.IV.1974, ster., Abraham 14 (MO, P); Kirindy forest, 20°03'16"S 44°40' 58"E, 89 m, 19.I.2007, fl., De Block et al. 2183 (BR); ibid. loco, 4.5 km E of rte 8 along S boundary of forestry block CN4, 20°04'S 44°40'E 35 m, 25.III.1992, fr., Noyes et al. 1070 (MO, P, WAG); Morondava, 1990, fr., Rahanyamalala s.n. (P); Kirindy forest, 20°04'04"S 44°39'38"E, 57 m, 11.IV.2013, fr., Randrianaivo et al. 2308 (MO); ibid. loco, 20°05'S 44°38'E, 45 m, X.1990, fr., Schatz 2989 (CAS, MO, P, TAN); village Marofandilia, lieu Kirindy, 27.II.1988, fr., Service Forestier 31899 (TE F). Sine loco: II.1955, fl. & fr., Descoings 400 (MO, TAN).