Miconia albertobrenesii Gamba & Almeda

Description

Description Author and Date: Diana Gamba & Frank Almeda, modified from "Systematics of the Octopleura Clade of Miconia (Melastomataceae: Miconieae) in Tropical America". Gamba, D., Almeda, F. Phytotaxa 179(1): 1-174.

Type: COSTA RICA. Prov. Alajuela: Los Ángeles de San Ramón, camino a la finca Johanson, 4 May 1928, Brenes 6160(holotype: F!; isotypes: CR, NY!). Nec Miconia brenesii Standley (1938: 816–817).

Description: Subshrub or tree (0.5–)1–9 m tall, moderately and openly branched, bark light green. Upper internodes rounded-quadrate, 1.9–4.9(–7.2) cm long, cauline nodes terete, nodal line present but concealed by the dense pubescence. Indumentum on branchlets, petioles, primary, secondary, tertiary and higher order veins abaxially, inflorescence axes, bracts, bracteoles, hypanthia, calyx lobes, calyx teeth, and petals abaxially densely to moderately composed of single-tiered lepidote trichomes 0.13–0.15 mm in diameter with radii nearly completely fused, seemingly mealy-furfurceous, typically copiously intermixed with elongate moderately roughened trichomes up to1 mm long, each trichome claviform and somewhat thickened. Leaves of each pair isophyllous; the thick petioles 1.5–2.9(–3.8) cm long, adaxially canaliculate and somewhat depressed, rounded abaxially; blades 13–25(–36) × 7.5–13.5(–22) cm, elliptic to ovate-elliptic, the base acute, the margin entire to obscurely undulate-crenulate, the apex acute to acuminate, chartaceous; mature leaves adaxially with surface at first sparsely covered with the mealy-furfuraceous general indumentum but soon becoming glabrate, primary, secondary, tertiary and higher order veins glabrous; abaxial surface glabrous, the tertiary and higher order veins completely lacking the elongate roughened trichomes; 5- or 7-plinerved, including the tenuous marginals, innermost pair of secondary veins diverging asymmetrically from the primary vein 0.6–1.2(–6) cm above the base, areolae 0.2–0.3 mm, adaxially the primary, secondary, tertiary and higher order veins flat, abaxially the primary and secondary veins elevated and terete, the tertiary and higher order veins slightly elevated. Inflorescences an erect pseudolateral thyrsoid 5.5–13 cm long, including a peduncle (1–)2(–3.3) cm long, highly and divaricately branched from the peduncle apex, borne on the upper foliar axils, the rachis thick and whitish; bracts 1.5–2 × 0.85–1 mm, elliptic ovate to lanceolate, concave, with conspicuous parallel venation, adaxially glabrate, abaxially with a denser indumentum forming a central band, becoming sparse toward the margins, early deciduous at anthesis; bracteoles 1.5–2.5 × 0.6–0.9 mm, oblong-oblanceolate, acute at the apex, concave, with conspicuous parallel venation, the indumentum like that of the bracts, early to tardily deciduous in fruit. Flowers 5-merous, sessile. Hypanthia at anthesis 2–2.7 × 1.2–1.5(–1.8) mm, free portion of hypanthium 1–1.5(–1.9) mm long, suburceolate to globose in fruit, bluntly 10-ribbed, green-white, ridged on the inner surface, minutely glandular, the glands somewhat translucent, sessile and rounded, the torus glabrous adaxially. Calyx open in bud and persistent in fruit, green-white; tube 0.6–1 mm long, glabrous adaxially and as the hypanthium abaxially; lobes 0.3–0.5 × 1.3–1.45 mm, broadly rounded, the margin vaguely undulate, the apex rounded-obtuse; exterior calyx teeth 1–2 mm long, triangular, inserted on the apical half of the lobes and projecting beyond them. Petals 2.4–2.9 × 1–1.4 mm, oblong-lanceolate, the margin entire, the apex bluntly acute, white, adaxially slightly papillose on the basal-central portion, abaxially glabrous at the margins, reflexed at anthesis. Stamens 10; filaments 1.5–2 × 0.25 mm, white, glabrous; anther thecae 1–1.5 × 1–1.3 mm, oblong-obovate, emarginate at the apex, opening by two dorsally inclined pores 0.15–0.2 mm in diameter, pale yellow to yellow, browning with age; connective pale yellow to greenish, its prolongation and appendage 0.25–0.3 mm long, the appendage lanceolate, bluntly acute at the apex, copiously glandular at the edges and on both surfaces, the glands rounded and stalked. Ovary 5-(6-) locular, completely inferior, 1–1.2 mm long at anthesis, the apical collar 0.3–0.5 × 0.25–0.32 mm, slightly depressed and bluntly ridged, sparsely glandular-puberulent; style 5.5–8 mm long, parallel sided (i.e. terete), white, glabrous; stigma expanded truncate to capitellate at anthesis. Berries 3–4.5 × 4–5 mm when dry, globose-oblate, white when ripe, the hypanthial indumentum persistent at maturity. Seeds 0.3–0.41 × 0.15–0.21 mm, ovoid, angled, brownish; lateral and antiraphal symmetrical planes ovate, the highest point toward the chalazal side; raphal zone suboblong to sublinear, ca. 90% the length of the seed, ventrally expanded toward the micropyle; appendage absent, but a small protuberance is sometimes present; individual cells elongate, anticlinal boundaries channeled, undulate, with ?- and U-type patterns; periclinal walls convex, low-domed, microrelief inconspicuously striate.

Habitat and Distribution: Locally common in primary rain forests and cloud forests, growing in the understory usually near stream margins, from Isla de Ometepe in Nicaragua, through southern Central America becoming uncommon in Colombia and Ecuador, at 100–1700 m. In Colombia and Ecuador it is known from the Pacific Andean slope, with a southernmost population from Cotopaxi in Ecuador. Manakins, Tanagers, Thrushes, the orange-billed Sparrow (Arremon aurantiirostris) and Myadestes melanopshave been reported to feed on M. albertobrenesii fruits in a Costa Rican rain forest (Stiles & Rosselli 1993). The following bird species have also been reported to feed on M. albertobrenesii fruits: Chlorospingus opthalmicus, Corapipo altera, Schiffornis turdina, Tachyphonus delatrii (Boyle 2006).

Phenology: Collected in flower and fruit throughout the year.

Etymology: The specific epithet commemorates Alberto Manuel Brenes (1870–1948), a school teacher in Costa Rica, who collected the type and many other flowering plants in the San Ramón area of Costa Rica over many years.

Taxonomy and Systematics: This species is distinguished by its dense mealy-furfuraceous indumentum, venules that are densely alveolate and conspicuously elevated abaxially, marked asymmetrical plinervation, and berries that are white at maturity. Within the Varibilis subclade, Miconia albertobrenesii is close morphologically and phylogenetically to M. boekei with which it shares the thickened-claviform indumentum and striking plinervation, but clearly distinct from it based on the color of mature berries (white in M. albertobrenesii vs. orange), and other vegetative characters (see M. boekei discussion). It is also similar and closely related to M. neomicrantha which also has white berries, but the flowers are 4-merous (vs. 5-merous), and the indumentum is not mealy. The indumentum of the latter two species is different in structural detail, but both types of trichomes are appressed to the surface, seeming more scale-like (as opposed to the dendritic trichomes that are not appressed and in which the arms are more conspicuous). This scale-like indumentum which is essentially squamate is also found in M. laxivenula (inconspicuous vegetative indumentum) and on the abaxial foliar veins in M. magnifolia. The presence of this kind of indumentum appears to be scattered among species of the Variabilis subclade which suggests that it has evolved several times within this clade. This species is distinguished by its dense mealy-furfuraceous indumentum, venules that are densely alveolate and conspicuously elevated abaxially, marked asymmetrical plinervation, and berries that are white at maturity. Within the Varibilis subclade, Miconia albertobrenesii is close morphologically and phylogenetically to M. boekei with which it shares the thickened-claviform indumentum and striking plinervation, but clearly distinct from it based on the color of mature berries (white in M. albertobrenesii vs. orange), and other vegetative characters (see M. boekei discussion). It is also similar and closely related to M. neomicrantha which also has white berries, but the flowers are 4-merous (vs. 5-merous), and the indumentum is not mealy. The indumentum of the latter two species is different in structural detail, but both types of trichomes are appressed to the surface, seeming more scale-like (as opposed to the dendritic trichomes that are not appressed and in which the arms are more conspicuous). This scale-like indumentum which is essentially squamate is also found in M. laxivenula (inconspicuous vegetative indumentum) and on the abaxial foliar veins in M. magnifolia. The presence of this kind of indumentum appears to be scattered among species of the Variabilis subclade which suggests that it has evolved several times within this clade.

Conservation Status: Following IUCN criteria (AOO), this species would be considered Endangered EN B2ab(iii). However, it occurs in many protected areas throughout its range, justifying a status of Least Concern LC. In Colombia it is proctected in the Farallones National Park (Valle) and in the Río Ñambí Natural Reserve (Nariño). In Costa Rica it is known from the Monteverde Reserve, Volcán Tenorio National Park, the San Ramón Forest Reserve, and the Alberto Brenes Biological Reserve (Alajuela); from La Marta Wild Life Refuge (Cartago); from the private protected area of Rara Avis Reserve, La Selva Biological Station (Heredia); and from the Braulio Carrillo National Park (Heredia, San José and Limón). In Ecuador it is known from the Awá Indigenous Reserva (Carchi and Esmeraldas), and from the borders of the Cotacachi-Cayapas Reserve. In Panama it is known from the Palo Seco Protected Forest (Bocas del Toro); from the Omar Torrijos National Park (Coclé); and from Darién National Park (Darién).

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Images

Ossaea brenesii: Photo taken in the field. (image/jpeg)

Ossaea brenesii: Photo taken in the field. (image/jpeg)

Ossaea brenesii: Photo taken in the field. (image/jpeg)

Ossaea brenesii Standl.: Photo taken in the field. (image/jpeg)

Ossaea brenesii Standl.: Photo taken in the field. (image/jpeg)

Ossaea brenesii Standl.: Photo taken in the field. (image/jpeg)

Ossaea brenesii Standl.: Photo taken in the field. (image/jpeg)

Ossaea brenesii Standl.: Photo taken in the field. (image/jpeg)