Miconia suberosa Meirelles & R. Goldenb., 2014

Meirelles, Julia & Goldenberg, Renato, 2014, A new species of Miconia (Miconieae, Melastomataceae) from the Brazilian Amazon, Phytotaxa 173 (4), pp. 278-284 : 280-282

Miconia suberosa Meirelles & R. Goldenb. , sp. nov.

sect. Miconia DC. (1828: 183) subsect. Seriatiflorae Naudin (1849 –1853: 427)

Type:— BRAZIL. Amazonas: Borba, Reserva de Desenvolvimento Sustentável do Igapó-Açu , 4°42’35.03”S 61°17’36.93”W, 26 October 2011, J. Meirelles & D. Silva, 795 (holotype: INPA! ; Isotypes: UPCB! , NY! , UEC! , MG! ).

Miconia suberosa is distinguished from other species from subsection Seriatiflorae by its deeply fissured bark with a thick cork, long dendritic hairs with short arms on young branches, inflorescences and leaves, petiolated leaves with rounded to obtuse bases and ciliate margins that are congested at the apices of branches, and truncate stigma.

Treelet 5–6 m high; branches rounded to quadrangular, densely covered by dendritic hairs with short arms; bark with a cork layer ca. 3.5 cm thick, deeply fissured (depressions 2–4 mm deep), with rounded ant holes ca. 0.7 mm diam. Leaves opposite, congested in the terminal portion of the branch; petioles 1.5–7 cm long, densely covered by dendritic hairs with short arms; blades 24.5–47.5 X 8–19 cm, oblong, apex acuminate, base rounded to obtuse, margin ciliate, chartaceous, longitudinal nerves 3 plus a faint marginal pair, acrodromous, basal to shortly suprabasal (inner pair up to 8 mm distant from the base), transversal veins 43–50, discolorous, adaxial surface dark green, slightly bullate, glabrous to moderately covered with dendritic hairs 0.4–0.7 mm long, abaxial surface yellowish to tan, slightly foveolate, densely covered with stellate 0.4–0.6 mm diam., canescent hairs on the blade surface and dendritic ferruginous hairs 0.2–0.8 mm long on the veins. Inflorescences in panicles 10–37 cm, terminal, densely covered by dendritic hairs with short arms, branches of the inflorescence in a helicoid cyme; bracts 1.3–2 X 0.1–0.2 cm, linear, adaxial surface sparsely covered with dendritic hairs, abaxial surface densely covered with dendritic hairs with short arms; bracteoles 1.6–2.1 X 0.3–0.4 mm, linear, adaxial surface glabrous, abaxial surface densely covered with stellate, canescent hairs with short arms. Flowers pentamerous. Hypanthium 1.5–1.7 mm long (from the base to the torus), campanulate, densely covered with stellate hairs. Calyx persistent, truncate, tube 0.7 mm long, external teeth 0.2–0.4 mm. Petals 2.1–2.5 X 0.7–1.2 mm, white, oblong, apex round to retuse, margins entire, both surfaces glabrous. Stamens 10, white, slightly dimorphic in size, antesepalous with filaments 3.1–3.7 mm long, antepetalous 2.5–2.9 mm, both glabrous; connectives prolonged ca. 0.2 mm below the thecae, the antesepalous with skirt-like appendages, ventrally slightly bilobed, and the antepetalous without skirt-like appendages, only with a small dorsal spur 0.2 mm long; anthers 1.5–1.6 mm in the antesepalous, 1–1.1 mm in the antepetalous, white, subulate, apex attenuate, pore ventrally inclined ca. 0.1 mm diam. Ovary 1–1.2 mm long, basally 2/3 inferior, 3-celled, the apex glabrous; style 3.5–7 mm long, straight, glabrous, stigma truncate. Fruits elliptical, green or orange when immature, black when ripe. 5.6 X 6 × 7.7 mm; seeds 2.3–2.7 X 1.6–1.9 mm, 5–8 per fruit, ovoid, angled, appendage absent, raphal zone obovate, the length covering 90–100% of the total length of the seed ( Figures 1 , 2 , 3 ).

Additional material examined: Brazil. Amazonas: Estrada Manaus Porto Velho, Rio Castanho, Igarapé do Tupanazinho , 17 July 1972 (bud), M. F. Silva 796 ( INPA) ; BR-319 ca. Km 235, Igapó-Açu black water várzea , 24 Nov. 1973 (fr.), E. Lleras & O. P. Monteiro P19674 ( INPA) ; Borba, RDS Igapó-Açu , 26 Oct. 2011 (bud), J. Meirelles & Silva, D. 784 ( INPA, UPCB) .

Distribution and habitat – Miconia suberosa is only known from the margins of blackwater rivers in Brazilian Amazonian forests, where it occurs in a transitional habitat between Terra Firme and Igapó forests. This species was collected in the Municipalities of Careiro Castanho and Borba, both of which are located south of the Solimões River, and north of the Madeira River.

Conservation status – Miconia suberosa is only known to occur within the Sustainable Development Reserve Igapó Açú, in the state of Amazonas. At least one of population of M. suberosa is protected and the area of occupancy of this species is of approximately 8.000 km ² of continuous forest, indicating that this species cannot be considered endangered following the IUCN (2014) ctiteria. However, it is noteworthy that the entire region will be highly threatened by the rebuilding of the BR-319 road, which is planned to start soon. Many other endemic species besides M. suberosa will be affected as road improvements tend to intensify development, and increase deforestation ( Fearnside et al. 2009).

Etymology – The epithet suberosa refers to the thick cork found on the bark of these plants. The trunks of this species seem to be submerged in the river waters during the rainy season, when the thick cork seems to act as an insulating mechanism.

Taxonomy – Miconia suberosa can be placed in section Miconia DC. (1828: 183) due to its short, linear, single-pored anthers with skirt-like and ventrally bilobed connective appendages. Within section Miconia , this species belongs to subsection Seriatiflorae Naudin (1849 –1853: 427). According to Cogniaux (1891), the species of subsect. Seriatiflorae have pyramidal panicles with bifid or trifid second (subscorpioid) branches.

Among the species of subsect. Seriatiflorae , only Miconia dispar Benth. (1850: 241) has a tree habit and leaves that are as large as those of M. suberosa . However, the leaf margins of M. dispar are not ciliate as in M. suberosa . While the petioles and inflorescences of both species are covered with stellate-dendritic hairs; those of M. dispar are thicker and shorter than those of M. suberosa (0.2–0.5 mm long in M. dispar vs. 0.6–1 mm in M. suberosa ). In addition, Miconia dispar has smaller petals (1.5–2 mm long vs. 2.1–2.5 in M. suberosa ) and capitate stigmas (vs. truncate stigmas in M. suberosa ).

Miconia secundiflora Cogn. (1886: 285) is another species of subsect. S eriatiflorae, that resembles M. suberosa . Both species share discolorous, bullate leaves with ciliate margins; however, these species differ from M. suberosa by the shrubby habit and sessile leaves with an amplexicaul base. In addition, M. secundiflora is endemic to the campinaranas (forests growing on white sand soils) from the state of Pará.

Miconia suberosa is also vegetatively similar to M. rugosa Triana (1871: 106) , from sect. Adenodesma (Naudin) Cogn. (1886: 217) due to the long ferrugineous hairs and large leaves. Nevertheless, M. rugosa has leaves with strongly supra basal venation (vs. basal to shortly suprabasal in M. suberosa ), spicate inflorescences with glomerulate flowers (vs. panicle with branchs disposed in helicoid cymes in M. suberosa ), and large purple anthers with glandular connectives (vs. short white anthers with non-glandular connectives in M. suberosa ).

Ecology – Miconia suberosa is myrmecophilous, housing ants of the genus Pheidole in cavities along the cork of its branches. These ants usually bring debris to the branches, petioles, and the base of the blades (on the abaxial surface), some of which are found in herbarium specimens. In the genus Miconia myrmecophitic species are rare. According to Michelangeli (2010), only four species from sections Amblyarrhena (Naudin) Triana ex Hook.f. (1867: 763) and Tamonea (1886: 238) are known to house ants in hollow stems however, none of these species are morphologically similar or closely related to M. suberosa .

Figures

FIGURE. 1. A–H. Miconia suberosa (drawn from the holotype). A. Habit with details of the indumentum. B. Detail of a dendritic hair with short arms. C. Detail of an ant cavity. D. Flower. E. Hypanthium. F. Antesepalous stamen in lateral view showing skirtlike appendage. G. Fruit with persistent calyx. H. Pheidole ant.

FIGURE. 2. A–F. Miconia suberosa. A. Twig with leaves congested at the apex. B. Deposition of organic material in the petioles and branches. C. Pheidole ant. D. Trunk with suberous bark. E. Inflorescence. F. Fruiting branch.

FIGURE. 3. A–D.Miconia suberosa. A. Indumentum on the abaxial surface of the leaf. B. Indumentum on the central vein (abaxial surface). C. Seed. D. Seed surface.