Eugenia manonae N. Snow & Rabenant., 2012

Snow, Neil, Rabenantoandro, Johny, Randriatafika, Faly, Rabehevitra, David, Razafimamonjy, N. Darie & Cable, Stuart, 2012, Studies of Malagasy Eugenia (Myrtaceae) - III: Seven new species of high conservation concern from the eastern littoral forests, Phytotaxa 48 (1), pp. 39-60 : 44-46

Eugenia manonae N. Snow & Rabenant. , sp. nov., ( Figs. 2 , 4 ).

A congeneribis madagascariensibus combinatione characterum sequentium distinguitur: cortex brunneus; rami glabri; flores solitarii terminales ex pedicellis glabris crassis orientes; calyx albidus sed marginibus magenteis; petala pallide rosea; styli et filamenta pallida; antherae luteae.

Type: ― MADAGASCAR. Prov. Toliara: Tolagnaro region, SW of town in forest called Petriky , along coastline near S end of the most SW lake, 22 January 1990, G. McPherson 14855, N. Dumetz & R. Rabevohitra (holotype MO! [sheet no. 3771521); isotypes P, TAN ).

Trees or shrubs 1–12 meters; bark somewhat flaky, mottled in patches of various sizes in gray, light brown, orange or green. Plants glabrous except where noted. Branchlets terete, greenish (drying light brown to light gray), smooth; oil glands common, distinct, of uniform size; internodes (1.0–)1.5–3.0 cm long, the younger ones sparsely and shortly sericeous above base of petiole (use magnification). Leaves coriaceous, evenly distributed along branchlets, emerald green above and below, slightly glossy above and matte below (drying brownish and slightly discolorous); venation brochidodromous. Stipular hairs few but obscure with younger leaves. Petioles 3.5–6(–9.5) mm long, sulcate at least proximally. Leaf blades (2.5–)4.0–6.5 x 2.5–4.0 cm, elliptic (mostly) to occasionally broadly elliptic or obovate, base cuneate, margin slightly revolute, laminar surface mildly wavy, apex obtuse, tip obtuse or occasionally abruptly narrowed and acute; adaxial surface oil glands dense but faint, midvein impressed more or less throughout or at least proximally; abaxial surface oil glands common to dense but faint, secondary veins 6–11 per side, protruding slightly (dry), marginal vein faint, 1.5–2.0 mm from laminar margin at midpoint, arching only slightly between tips of secondary veins. Inflorescence terminal, consisting of 1–2 solitary flowers per axil. Peduncles 9–15 mm long, stiff, terete, ascending, glandular, light green. Bracteoles inferred from scars but otherwise unknown. Hypanthium obconic, terete, glabrous, yellowish-green. Calyx lobes 4, 6.6–7.5 mm (as measured on mature fruit), dimorphic (outer ones shorter and narrower), broadly ovate to semi-circular or oblate, glabrous, whitish but with a distinct, narrow marginal band colored magenta that fades to some degree during anthesis, imbricate in bud, persistent in fruit. Petals light pinkish-white to light pink, length and width unknown, oil glands common. Stamens numerous (100+); filaments white; anthers globose, length not measured, ivory to stramineous. Style whitish, slightly longer than longest filaments, gradually tapering in diameter towards apex; stigma very narrow, terete. Fruits 1.8–2.5 x 1.2–2.1 cm, globular, terete, greenish becoming orange to yellowish; exocarp relatively thin, soft, ca. 0.7 mm thick, densely glandular (glands of varying sizes), heavily vascularized with numerous vertical strands of varying thickness (easily seen in dry or rehydrated material). Seeds 1–2 per fruit, ca. 18.0 x 11.5 mm, compressed oblate; testa leathery, ca. 0.3 mm thick, densely glandular; hypocotyl elongate, fused into and flush with cotyledons.

Field characters:— Shrubs or trees up to 12 meters, outer bark thin and peeling irregularly, brownish with shades of orange and green. Plants glabrous apart from the sparse covering of hairs at base of internode above younger petioles. Flowers terminal, arising from stout pedicels. Hypanthium light yellowish-green. Calyx lobes whitish but margins strongly magenta in bud, persistent and crowing mature fruit. Petals light pink. Filaments and style white; anthers cream-colored. Fruits globular, greenish-yellow to yellowish-orange.

Distribution:— Southeastern Madagascar, from west of Tolagnaro to Sainte Luce, from three collections scattered across approximately 50 km. The type gathering southwest of Petriky Forest is not in a conservation area ( Fig. 2 ). The northernmost paratype gathering ( Fig. 2 ) is evidently located in the conservation zone (S9) in Sainte Luce (see also Lowry et al. 2008).

Habitat and ecology:— In dense shrubby vegetation and littoral forests over sand.

Phenology:— Flowering in October, November and possibly into December. Fruiting in January.

Additional specimens examined (paratypes):— MADAGASCAR: Prov. Toliara: Sainte Luce, QMM Forestry Station, parcel S9 [not “59”, as written on label], 1–2 km from QMM Forestry trailhead, 24°46’05”S, 47°10’16”E, 23 January 2006, Z. S. Rogers 968, R. Ranaivojoana, C. Davidson, & S. R. Christoph (BISH! [sheet no. 744885]; MO, P, TAN); Jardin Botanique de Manena , 24°57’10.08”S, 47°00’10.39”E (see note below regarding geocoordinates), 25-26 October 1989, R. Rabevohitra 2075 (K!, MO!; P, TAN) .

Epynomy:— The species honors Manon Vincelette (b. 1959), a long-term resident of Madagascar who has contributed significantly to its conservation programs and who implemented the forest restoration program at Fort Dauphin of Rio Tinto QMM (e.g., Vincelette et al. 2008).

Conservation status:— The written description associated with the type gathering allows us to infer with reasonable confidence its position at about 25°05’50”S, 46°50’25”E somewhat southwest of Petriky forest , near the coast. The type locality is evidently a narrow band of littoral forest that varies from ca. 50–200 meters wide in that area. The paratype of Rogers et al. from Sainte Luce was georeferenced at the time of its collection and is approximately 2.7 km west of the coast and directly west of Sainte Luce in a relatively large and mostly undisturbed forest remnant, possibly located within conservation zone S9 of Sainte Luce (see Lowry et al. 2008). The collection label of Rabevohitra 2075 indicates “Jardin Botanique de Mandena” as the locality. A string of recent communications with workers from Missouri Botanical Garden and colleagues in Madagascar, including Rabevohitra, suggest that the “botanical garden” locality is in a conservation zone in Mandena. Based on recent satellite imagery, the coordinates cited above as being most likely to reflect the collection locality are in an area that appears to be mostly altered by mining activities. We are thus unable to determine precisely the origin of that specimen .

In light of its distribution at three general areas, which includes a relatively undisturbed area west of Sainte Luce, and the likelihood of additional individuals occurring between the three locations, we assign a preliminary status of Vulnerable (VU: A1c,B2a,b(ii)).

Discussion:— The description of E. manonae is based on three herbarium specimens and several unvouchered digital images, which we are confident match the herbarium material. The absence of flowering material among herbarium specimens prevented inclusion of some descriptive information (e.g., width and length of petals, filaments, and style). Notes on the label of the type specimen indicated that the magenta margin of the calyx lobes can persist with mature fruits. The number of petals is uncertain; Fig. 4 (lower right) shows five of evidently six pinkish petals rather than the typical number of four, although it is uncertain whether this is an aberration.

Approximately fifteen larvae of an undetermined white fly (Class Homoptera; family Aleyrodidae ), probably representing the first instar, were located on the abaxial leaf surface of the holotype specimen (vouchers at Bishop Museum).

Figures

FIGURE 2. Distribution of species and selected specimens of Eugenia in southeastern Madagascar based on vouchered herbarium specimens and recently captured (but non-vouchered) digital images. Remaining forested areas (Petriky, Mandena, Sainte-Luce) along the coast are indicated in gray. In cases where the icons largely or completely overlapped based on geo-coordinates they have been separated slightly for easier viewing (e.g., E. ardyceae, E. stictophylla and E. cloiselii along the coast west of Tolagnaro). Many additional specimens of Eugenia from the region await identification or description and cannot be mapped confidently at the present time.

FIGURE 4. Eugenia manonae. Upper left: main bole. Upper right: branchlet. Lower left: terminal buds. Lower right: flower with evidently six petals. (No voucher; photos by D. Rabehevitra).