Miconia approximata 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: PANAMA. Prov. Bocas del Toro: Region of Almirante, Buena Vista Camp, 11 March 1928, Cooper 575 (holotype: F!; isotypes: K-internet image!, NY!, US-internet image!, WIS-internet image!).

Description: Shrub (0.5–)1–3(–3.5) m tall, commonly forming thickets, main stem branching at around 1 m, the branches pendant and sometimes sprawling over adjacent plants, bark brownish. Upper internodes [(1–)1.5–6.8 cm long] and cauline nodes terete, nodal line absent. Indumentum on branchlets, petioles, primary and secondary leaf veins abaxially, bracts, hypanthia, calyx lobes abaxially, and exterior calyx teeth densely composed of brown elongate slightly roughened trichomes 0.3–0.7 mm long, each trichome clavate and somewhat thickened, sparsely intermixed with, or occasionally completely replaced by a brown understory of dendritic trichomes 0.05–0.15 mm long with short to moderately long thin-walled (flattened) arms. Leaves of each pair somewhat anisophyllous in size, some pairs isophyllous; the short terete petioles 0.3–0.8(–1) cm long, brownish, occasionally pink; larger blades 12–22 × 4.8–9.3 cm, smaller blades (4.5–)5–11.2 × 2–4.5 cm, narrowly elliptic to elliptic or slightly elliptic-obovate, the base acute to obtuse, the margin entire to obscurely undulate-serrulate, the apex gradually acuminate to long-acuminate, firm-membranaceous; mature leaves with adaxial surface glabrescent, in young leaves copiously covered with the general dendritic trichomes, the primary, secondary, tertiary and higher order veins glabrous; abaxial surface essentially glabrous except for a few glands coming on the venules, the tertiary veins moderately covered with the general dendritic trichomes, along with the higher order veins, copiously to sparsely beset with resinous sessile to short-stalked glands 0.05 mm long with thin-walled short to elongate heads, frequently intermixed with and occasionally replaced by white or brown-translucent furrowed sessile glands of the same length ; 5-nerved, including the tenuous marginals, areolae 0.5–1 mm, adaxially the primary, secondary, tertiary and higher order veins flat, abaxially the primary and secondary veins elevated and terete toward the blade base, flat toward the apex, the tertiary and higher order veins flat. Inflorescences a congested axillary fasciculate glomerule <1cm long, sessile, unbranched, paired or solitary among upper leafy nodes, seeming cauliflorous on defoliated nodes; bracts 1.5–3 × 0.5–1 mm, triangular to oblong, persistent to tardily deciduous in fruit. Flowers 4-merous, sessile. Hypanthia at anthesis 2.4–2.5 × 1.4–1.5(–2.2) mm, free portion of hypanthium 1 mm long, suburceolate to more or less globose, 8-ribbed, pinkish to green, the ribs frequently concealed by the dense general indumentum, ridged on the inner surface, minutely glandular, the glands sessile and rounded, the torus densely glandular with minute sessile to short-stalked rounded glands adaxially. Calyx open in bud and persistent in fruit, green; tube 0.2–0.25(–0.3) mm long, adaxially with the same vestiture as the torus, abaxially with the same indumentum as the hypanthium; lobes 1–1.5 × 1–1.5 mm, rounded-ovate to triangular, the margin entire, the apex rounded-obtuse, adaxially glabrescent, reflexed at anthesis; exterior teeth 0.5–1 mm long, subulate, inserted on the apical half of the calyx lobes and slightly projecting beyond them. Petals 2.5–2.6 × 0.9–1 mm, ovate-oblong to linear-oblong, the margin entire, the apex rounded-obtuse, white to pale-pink, glabrous on both surfaces, reflexed at anthesis. Stamens 8; filaments 1–1.5 × 0.2–0.25 mm, white, glabrous; anther thecae 1.4–1.5 × 0.25–0.33 mm, linear-oblong, more or less truncate to slightly emarginate at the apex, opening by one dorsally inclined pore 0.07–0.1 mm in diameter, white or pale pink, becoming brown with age; connective white, also becoming brown with age, its prolongation and appendage 0.35–0.45(–0.5) mm long, the appendage deltoid-lanceolate, bluntly acute to obtuse at the apex, copiously gland-edged and covered with stalked or subsessile glandular trichomes to 0.15 mm long, denser dorsally and present throughout the connective. Ovary 4-locular, 3/4 inferior, 1.7–1.8 mm long at anthesis, the apical collar (0.3–)0.4–0.5 × 0.25 mm, conic, copiously glandular-puberulent; style 2.5–3.5 mm long, more or less parallel sided (i.e. subterete), white, glabrous or with few glands at the very base; stigma truncate to capitellate. Berries 2–2.5 × 5–6 mm when dry, globose-oblate, bright orange when ripe, the hypanthium indumentum somewhat persistent at maturity. Seeds 0.52–0.57 × 0.31–0.4 mm, pyramidal, yellow-brown; lateral symmetrical plane triangular, the highest point near the central part of the seed, with a foot-like projection at the micropylar end; antiraphal symmetrical plane suboblong; raphal zone suboblong, ca. 60–80% the length of the seed; multicellular sculpture rugose throughout the seed; individual cells elongate, anticlinal boundaries channeled, undulate, with ?- and U-type patterns; periclinal walls convex, low-domed to nearly flat, microrelief striate. Chromosome number: n=17.

Common names: Honduras: “sirin” (Standley 52936 and Gentle 4373).

Habitat and Distribution: This is a locally common species in the understory of primary rain forests where it also colonizes disturbed sites throughout Central America from Belize and Guatemala (except El Salvador), to southern Panama, and extending to Colombia and Ecuador, at 0–1400(–1759) m. In the TROPICOS database there are two Ecuadorian specimens that were not examined in this study. One is from Pichincha (Øllgaard 37630, AAU), and the other from Esmeraldas (Holm-Nielsen 25472, AAU). Miconia approximata is one of the most widespread species in the Octopleura clade. It appears to be especially common in Central America. White-ruffed Manakins (Corapipo altera) have been reported to feed on M. approximata berries in a wet forest of northeastern Costa Rica (Boyle 2010). Other fruit-eating birds of the tropical forest understory (at Estación Biológica La Selva, Costa Rica) have been reported to consume M. approximata berries, including Chlorothraupis carmioli, Corapipo leucorrhoa, Euphonia gouldi, Hylocichla mustelina, Mionectes oleaginous, and Pipra mentalis(Loiselle & Blake 1999, 2000).

Phenology: Collected in flower and fruit throughout the year.

Etymology: The specific epithet refers to the close proximity of the flowers in the congested glomerules that characterize this species.

Taxonomy and Systematics: This species is readily distinguished by its brownish thickened-clavate elongate trichomes mixed with a furfuraceous indumentum of dendritic trichomes, short and pubescent petioles, narrowly elliptic to elliptic leaves, and sessile congested fasciculate glomerules. Its closest relatives include species that share the congested fasciculate glomerules (M. chocoensis, M. quadridomius, and M. veraguensis) and also have elongate roughened trichomes (but different sizes and colors). Wurdack (1981) provides a detailed summary of similarities and differences between M. approximata and M. quadridomius (which he treated as Clidemia densiflora and C. cuatrecasasii respectively). Miconia veraguensis, a new species from Veraguas, differs primarily in berry dimensions which are bigger and modal differences in leaf shape. Miconia evanescens, which is also closely related and somewhat similar to M. approximata, has been confused in the past with this species, probably due to the poorly developed inflorescences in both, especially in Colombian material, where M. approximata only occurs in Chocó, and M. evanescens in Nariño. Although both species present abaxial foliar venules densely resinous-glandular, in M. evanescens the indumentum is whitish (vs. brownish), the hypanthium is green-whitish (vs. pinkisk green), and the ovary is completely superior (free from the hypanthium vs. 3/4 inferior). Quite a few populations from Costa Rica (Limón, Heredia/San José), Panama (Bocas del Toro, Coclé, Darién, Panama), Colombia (Chocó) and Ecuador (Pastaza), lack the claviform elongate slightly roughened trichomes, the vestiture being only composed of a dense to moderate brown furfuraceous indumentum of dendritic trichomes with short to moderately long thin-walled (flattened) arms. These pubescence variants do not appear to correlate with geography or elevation since these populations occur throughout the elevational range of the species and appear to be sympatric with typical forms of M. approximata. In all other vegetative and floral features M. approximata is quite uniform. A closely related taxon, and possibly distinct, was recently collected from the department of Chocó in Colombia (Almeda et al. 10459, CAS!, COL). It has narrower elliptic leaves, fewer flowers per node, and abaxial foliar venules densely covered with white furrowed sessile glands that are also sparsely present on the hypanthium and exterior calyx teeth. Superficially it is easily confused with M. approximata, but the white furrowed glands in the latter are fewer, although common not consistently present, and restricted to the leaves abaxially. This specimen only has immature fruits, making floral comparisons impossible. It is probable that the indumentum differences, specifically the location of these white furrowed glands (vegetatively or/and on hypanthia/calyx) is taxonomically significant, but it is premature to describe this entity based on the one imcomplete collection. Based on molecular data these two species are close to one another.

Conservation Status: Vulnerable VU B2ab(iii), based on IUCN criteria (AOO). However, this species occurs in many protected areas, warranting a status of Least Concern LC. Miconia approximata is protected in Colombia in the Ensenada de Utría National Park. In Costa Rica in the Monteverde Biological Reserve (Alajuela and Cartago); in La Selva Biological Reserve and the Braulio Carrillo National Park (Cartago, the latter also in Limón and San José); in the Hitoy Cerere Biological Reserve, Barra del Colorado Wild Life Refuge, the Pacuare Protected Zone, and the Tortuguero Nationl Park (Limón); in the Corcovado National Park, the Golfito Wild Life Refuge, the Piedras Blancas National Park, the Marenco Biological Station (Puntarenas); and in La Cangreja the Cerro Nara Protected Zones (San José). In Nicaragua it is protected in the Indio-Maíz Reserve (Río San Juan). In Panama it is protected in the Omar Torrijos National Park (Coclé); in the Chagres National Park (Panama); and in the Coiba National Park (Veraguas).

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