Eugenia stibephylla N. Snow & Rabeh., 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 : 53-54

Eugenia stibephylla N. Snow & Rabeh. , sp. nov. ( Figs. 2 , 8 ).

A congeneribis madagascariensibus combinatione characterum sequentium distinguitur: petioli longi et indumentum floccosum in foliis ramulsique iuvenibus.

Type: ― MADAGASCAR. Prov. Toliara: Tolagnaro region; W of town in forest called Mandena; trail through Botanical Garden , 24°57’S, 047°00’E, 25 m, 6 December 1989, G. McPherson 14647 & N. Dumetz (holotype MO! [sheet no. 04805046]; isotypes MO! [sheet no. 3771517], P, TAN) .

Trees to 8 meters; bark light to medium brown, irregularly fissured vertically, flaking irregularly in rectangular polygons. Indumentum of young branchlets and leaves whitish, hoary (frost-like) or floccose; indumentum of reproductive parts sericeous (trichomes dibrachiate, reddish-brown, especially on dry material). Branchlets laterally compressed, medium green to light brown (fresh) or light greenish brown (dried), smooth, somewhat pruinose, glabrous; oil glands sparse and indistinct; internodes 0.9–1.7 cm long. Leaves coriaceous, evenly distributed along branchlets, concolorous and medium green (fresh), strongly discolorous (dry), glossy above, matte below; venation brochidodromous. Stipules absent. Petioles 7–14 mm long, deeply and narrowly sulcate above, floccose when young, smooth, eglandular. Leaf blades (3.5–)5.0–7.0 x 2.3–3.6 cm, mostly elliptic (a few obovate), base cuneate, apex obtuse (rarely acute), tip obtuse, margin slightly revolute (fresh and dried), surface flat or slightly irregular; adaxial surface floccose when young but becoming sparsely and minutely sericeous in age (trichomes dibrachiate), oil glands not visible, midvein flush or slightly sulcate at base; abaxial surface hoary but becoming sparsely and minutely sericeous along base of midvein (trichomes whitish), oil glands common, prominent (less so on dried material, but see younger leaves), secondary veins faint (fresh) but prominent when dried, intramarginal vein indistinct, 1.5–2.0 mm from laminar margin at midpoint. Inflorescence a 3–9-flowered cyme (central flowers typically sessile or subsessile), solitary to paired or fascicled in the axils, sometimes on brachyblasts (bracteate short shoots); central axis ascending to erect, stiff, laterally compressed, moderately to densely sericeous (trichomes dibrachiate, brownish). Bracteoles ca. 1 x 1 mm, broadly elliptic to broadly ovate, scale-like, densely sericeous below but more or less glabrous above, ascending to erect, stiff, persistent or not in flower, yellowish or light brown to maroon (fresh). Hypanthium 1.8–2.1 mm long, 1.6–1.8 mm wide at base of calyx lobes, obconic, terete (fresh) but becoming slightly rugose when dried, densely sericeous; ovary apex glabrous. Calyx lobes 4, 2.0– 2.7 mm long, semi-circular, glabrous above, densely sericeous proximally but less so apically, light green drying brownish. Petals 4, 5.5–7.6 mm, very widely elliptic or very widely ovate to widely obovate, sparsely to moderately short ciliate (glabrous otherwise), white (tinged with pink in bud and sometimes towards base during anthesis), oil glands common. Staminal ring glabrous, 2.5–3.0 mm wide. Stamens ca. 105–125; filaments 5–6 mm; anther sacs 0.8–1.1 mm long, globose to subcylindrical, basifixed, with a prominent apical gland on connective. Style 5.0– 8.5 mm, glabrous; stigma terete and scarcely if at all capitate. Locules 2; placenta axile, capitate, arising from middle of locular wall; ovules 8–10 per placenta, radiating from placenta. Fruit unknown.

Field characters:— Trees to 8 meters tall; bark light to medium brown, vertically fissured; young leaves and branchlets bearing floccose (frost-like) indumentum; petioles relatively long; upper leaf surface glossy; leaves concolorous or nearly so when fresh; petals and filaments white (petals pinkish tinged in bud and near base during anthesis), anther sacs cream colored, style light green.

Distribution:— Eugenia stibephylla is presently known from the type gathering the Mandena conservation area and from the digital image ( Fig. 8 ) in a block of forest in Sainte Luce ( Fig. 2 ).

Habitat and ecology:— Occurring only in coastal littoral forests in sandy soils.

Phenology:— Flowering in December. Fruits not known; presumably by late December and at least into January.

Etymology:— From the Greek words stibe, in reference to the irregularly floccose, hoary young leaves and branchlets, and phyllum for leaf.

Conservation status:— Recent observations in the field suggest that that the species is represented by fewer than 500 individuals. With one collection known from a restricted protected forest (Mandena), an AOO of 9 km 2, and a single subpopulation constituting a single location with an estimated number of less than 500 individuals, encompassed within a protected area (Petriky), E. stibephylla is assigned a preliminary status of “Vulnerable” (VU: D1, 2).

Discussion:— The species is unmistakable among Malagasy Eugenia by virtue of its long petioles and the floccose, hoary indumentum of the emerging branchlets and leaves. The vertically fissured, medium brown bark is unlike other species of Eugenia in the Petriky Forest region.

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 8. Eugenia stibephylla. Upper left: bark of main bole. Upper right: emerging leaves showing hoary indumentum. Lower left: Adaxial surface of mature leaf showing oil glands. Lower right: flowers. (No voucher; photos by D. Rabehevitra).