A revision of the florbella group of Miconia (Melastomataceae, Miconieae) with description of three new species
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Institute of Systematic Botany, The New York Botanical Garden, Bronx, NY 10458-5126, USA; e-mail: [email protected] 2 Universidade Federal do Paraná, Caixa Postal 19031, CEP 81531-970, Curitiba, PR, Brazil
Abstract. The florbella group of Miconia is composed of four species from the central Andes that are characterized by hollow stems inhabited by ants, and pleiostemonous flowers with a calyptrate calyx. The four species are M. inusitata, and the newly described here M. cava, M. florbella, and M. valenzuelana. The combination of pleistemonous flowers and calyptrate calyces suggests that these species could be placed in the former Conostegia, but at least three of the four species discussed here (M. florbella, M. inusitata and M. valenzuelana) do not belong in that clade and are more closely related to other species of Andean Miconia. All four species grow in undisturbed areas in low- to middle-elevation forests in the Andes. Keywords: Calyptrate calyx, Conostegia, Florbella, Ecuador, mymercophyly, Peru, pleiostemony.
Conostegia D. Don was created by David Don (1823), probably following Bonpland’s ideas (Bonpland, 1816–1823) to accommodate berry-fruited, neotropical members of the Melastomataceae with calyptrate calyces. Shortly after, de Candolle (1828) made all the appropriate combinations in Conostegia of species with those characteristics that had been described in Melastoma L. Remarkably, most of these species are also pleiostemonous; that is, they have more than double the number of stamens than petals. This concept of Conostegia, including both calyptrate and pleiostemonous members of the Miconieae, was subsequently adopted by all other Melastomataceae specialists and has rarely been challenged (Naudin, 1850; Triana, 1871; Cogniaux, 1891). In that framework, Wurdack (1968) described a remarkable species from the central Peruvian Andes, Conostegia inusitata Wurdack. He noted that the winged hypanthium, four-merous flowers, and high number of stamens (up to 96) were quite different from other Conostegia and suggested that the species might be placed in its own infrageneric group. In an unpublished doctoral thesis, Schnell (1996) stated that C. inusitata differed from most species of Conostegia by calyx morphology and anther number and morphology.
The calyx in C. inusitata is foliose, thin, and apparently photosynthetic (vs. thick non foliose, and not green in other Conostegia), and dehisces 1–2 mm above the torus (vs. near or at the torus in Conostegia). In C. inusitata, the level of pleiostemony is much higher than in other species of Conostegia, with 80–100 anthers (vs. up to 30), and the anthers are relatively thinner, borne on comparatively longer filaments, and subulate (not laterally compressed). Based on these and other characters, Schnell (1996) argued that C. inusitata did not belong to Conostegia, proposing a new genus, “Florbella”, which not only included this species but also an undescribed one. This second species, for which Schnell proposed the name “Florbella wurdackii”, was also from central Per
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