Miconia bractiflora 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: COLOMBIA (Nouvelle Grenade). Nariño: Barbacoas, Arrastradero, 10 m, April 1853, Triana s.n. (holotype: BM-internet image!; isotypes: BR-2 sheets-internet images!, COL-internet image!, NY-2 sheets!).

Description: Shrub or small tree (0.7–)1–8 m tall with erect, rigid branching. Upper internodes compressed-rounded, (1–)3.2–7.1 cm long, cauline nodes terete, bearing a well-defined nodal ridge forming a deflexed flaplike outgrowth confluent with the abaxial bases of the petioles. Indumentum on branchlets, primary and secondary leaf veins abaxially, inflorescence axes, bracts and bracteoles, sparsely composed of caducous somewhat translucent dendritic trichomes 0.15–0.2 mm long with short thin-walled (flattened) arms. Leaves of each pair isophyllous; the semiterete petiole 1.5–4(–6) cm long, widely and deeply canaliculate adaxially, glabrous; blades 15–28(–35) × 5.5–16 cm, oblong-elliptic to obovate, the base acute to cuneate, narrowly decurrent on the petiole, the margin entire or obscurely undulate-crenate to crenate, the apex acute to short-acuminate, chartaceous; mature leaves adaxially with surface, primary, secondary, tertiary and higher order veins glabrous; abaxial surface occasionally red-flushed, glabrous like the tertiary and higher order veins; 5-(7-) plinerved, including the tenuous marginals, innermost pair of secondary veins diverging equilaterally or inequilaterally from the primary vein 0.6–1.2 cm above the base, areolae 0.5–1 mm, adaxially the primary, secondary, tertiary and higher order veins impressed, abaxially the primary and secondary veins elevated and terete, the tertiary and higher order veins slightly elevated. Inflorescences a pseudolateral multiflorous thyrsoid 3–7 cm long, including a peduncle 1–1.5(–2) cm long, the flowers congested in the paracladia, with a secund/scorpioid arrangement, pendant, divaricately branched from the peduncle apex among the upper foliar nodes; bracts and bracteoles 3–5 × 2–4 mm, the bracts ovate to suborbicular, acute at the apex, each pair imbricate, commonly more than one pair present, the bracteoles ovate-oblong to suborbicular, bluntly and widely acuminate at the apex, both concave, with conspicuous parallel venation, green-orange, glabrescent to sparsely furfuraceous on both surfaces, persistent to tardily deciduous in fruit. Flowers 5-merous, sessile. Hypanthia at anthesis 2.5–2.7 × 1.3–1.5 mm, free portion of hypanthium 1–1.2 mm long, campanulate to subglobose, bluntly 10-ribbed, greenish to orange, with a copious matted indumentum of dendritic trichomes 0.15–0.2 mm long with moderately long thin-walled arms, ridged and glabrous on the inner surface, the torus sparsely ciliate to glabrous adaxially. Calyx open in bud and persistent in fruit, green; tube 0.4–0.5 mm long, with the same vestiture as the torus adaxially and as the hypanthium abaxially; lobes 0.5–0.7 × 0.7–0.9 mm, broadly depressed triangular, the margin vaguely undulate, the apex bluntly acute, moderately to copiously covered on both surfaces with the same type of vestiture as the hypanthium; exterior calyx teeth up to 0.25 mm long in fruit, short-linear and blunt, with the same vestiture as the hypanthium, inserted at the base of the calyx lobes and not projecting beyond them. Petals 2–3.2 × 0.75–1 mm, oblong-lanceolate, the margin entire, the apex bluntly acute, white to translucent white, glabrous adaxially, abaxially with a copious central band of matted dendritic trichomes to 0.25 mm long with moderately long thin-walled (flattened) arms, reflexed at anthesis. Stamens 10; filaments 2–2.5 × 0.25 mm, white, glabrous; anther thecae 1.5–2.2 × 0.3–0.4 mm, linear-oblong, slightly clavate and emarginate at the apex, opening by two dorsally inclined pores, 0.11–0.13 mm in diameter, white to pale yellow; connective pale yellow, its prolongation and appendage (0.25–)0.3–0.4 mm long, the appendage deltoid, bluntly acute at the apex, copiously gland-edged, the glands short-stalked, also present on the dorsal side of the appendage and connective. Ovary 5-locular, 2/3 to 3/4 inferior, 1.9–2.1 mm long at anthesis, the apical collar absent, the apex 0.25–0.35 mm in diameter, conic-truncate, sparsely glandular-puberulent; style 3.8–4.5(–5) mm long, parallel sided (i.e. terete), white, glabrous; stigma expanded truncate to capitellate at anthesis. Berries 1.8–2.5 × 2.5–3 mm when dry, globose-oblate, initially green, then orange, ripening red-orange to red-purple, the hypanthial indumentum persistent at maturity. Seeds 0.37–0.4 × 0.13–0.17 mm, ovoid, angled, brownish; lateral and antiraphal symmetrical planes ovate, the highest point toward the chalazal side; raphal zone triangular to suboblong, nearly as long as the seed, somewhat ventrally expanded toward the micropyle; appendage absent but a small protuberance present; individual cells elongate, anticlinal boundaries channeled, undulate, with [Omega]- and U-type patterns; periclinal walls convex, low-domed to nearly flat, microrelief inconspicuously striate.

Habitat and Distribution: Locally common in primary or somewhat disturbed lowland rain forests and cloud forests, growing close to streams or river banks, from Cocos Island (Costa Rica), through Panama, to the Colombian Andes and northern Ecuador , at 0–1800 m. In Panama it occurs on both the Atlantic slope and the Pacific slopes. In Colombia it has been collected throughout the Pacific coast/western Andean slope and in the Central Andean Cordillera. In Ecuador it is known from the northwestern provinces of Esmeraldas and Carchi, with a southernmost occurrence in Los Ríos (Cerro Centinela). There are three specimens at COL identified as this species (Ruiz 376, 377 and 396) from Cauca (to 2450 m), Colombia, where it is certainly expected, but we cannot confirm that these correspond to this species based on the images in the IUCN portal.

Phenology: Collected in flower and fruit throughout the year.

Etymology: The specific epithet refers to the numerous bracts subtending the flowers on the inflorescences of this species.

Taxonomy and Systematics: This species is easily separated from its closest relatives by the congested flowers surrounded by conspicuous green-orange imbricate bracts and bracteoles throughout its short thyrsoid inflorescence. Cogniaux (1891a) assigned it to Ossaea section Bractearia, along with M. rufibarbis, which also has conspicuous bracts and bracteoles arranged along a verticillate interrupted spike. Both species, together with M. magnifolia, a new Colombian species described here (M. formicaria), and M. spiciformis form a clade that shares 5-merous flowers and multiflorous, copiously bracteate inflorescences (but with different architectures). Miconia bractiflora is sister to M. formicaria which has similar bracteate inflorescences with secund dichasial branching. The latter, however has conspicuous formicaria at the blade base adaxially, a unique character within the Octopleura clade. This species is known in Costa Rica only from Cocos Island (Trusty et al. 2006), where it is common (from 0–550 m) and probably arrived through bird dispersal. At present there are no studies documenting the bird species that feed on M. bractiflora berries. In Colombia it might be more widely distributed than present collections indicate since it was recently discovered on the eastern slope of the Central Cordillera (Alvear et al. 1474, CAS!, COL!).

Conservation Status: Based on IUCN criteria (AOO), this species would be considered Endangered EN B2ab(iii). However, a status of Least Concern LC is justified because it occurs in quite a few protected areas. Protected in Colombia in the Selva de Florencia National Park (Caldas) and in the Ensenada de Utría National Park (Chocó). In Costa Rica it is protected in the Isla del Coco National Park (Puntarenas). In Ecuador it is protected in the Awá Indigenous Reserve (Carchi and Esmeraldas) and in the Río Palenque Biological Station (Los Ríos).

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Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)

Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)

Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)

Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)

Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)

Miconia bractiflora Gamba & Almeda: Photo taken in the field. (image/jpeg)