Burmeistera minutiflora ( Campanulaceae-Lobelioideae ) , a new species from the high Andes of Antioquia ( Colombia ) with the smallest flowers in the genus

Garzón Venegas, J., González, F. & Vélez Puerta, J.M. Burmeistera minutiflora (Campanulaceae-Lobelioideae), a new species from the high Andes of Antioquia (Colombia) with the smallest flowers in the genus. Anales Jard. Bot. Madrid 69(2): 243-246. Burmeistera minutiflora (Campanulaceae-Lobelioideae), a new species of sect. Barbatae, is here described, illustrated, and keyed out with respect to other species of the genus with small flowers (i.e. corolla tube <1 cm long). The new species is a small herb that grows in the understory of remnants of cloud montane forests of the Western cordillera of Antioquia, Colombia. The dimensions of the corolla and the berries correspond without doubts to the smallest size of reproductive structures in the genus. The small floral size contrasts with the colorful, bright red and yellow corollas.

The most comprehensive revisions of Burmeistera were written by Wimmer (1931Wimmer ( , 1932Wimmer ( , 1943Wimmer ( , 1953Wimmer ( , 1968)), who recognized about 80 species arranged in two sections, Barbatae E. Wimm., and Imberbes (nom.invalid.= sect.Burmeistera Lammers; see Lammers, 1998), based on the indument of the apical margin of the anther tube.Although the monophyly of these two sections has been questioned by Knox & al. (2008), the presence of a tuft of trichomes in the apex of the ventral anthers in preanthetic flowers remains as a reliable diagnostic field character at a specific level (Garzón & al., 2012).
The first Colombian species were described by Kunth (1818, under Lobelia), but then Karsten & Triana (1856), Zahlbruckner (1906Zahlbruckner ( , 1915)), Wimmer (1931Wimmer ( , 1932Wimmer ( , 1943Wimmer ( , 1953Wimmer ( , 1968)), and most recently McVaugh (1965), Luteyn (1986), Lozano and Galeano (1986), Lammers & Maas (1998) and Lammers (2002) have described most of the species present in Colombia, where the genus reaches its highest diversity.The main species-level diagnostic characters in Burmeistera are the overall pubescence of the plant, the leaf architecture, the presence or absence of bracts at the base or the proximal third of the floral peduncle, the shape and size of the hypanthium, the calyx lobes, the shape, size and color of the corolla, and the size, shape, color, and consistency of the berries.

MATERIAL AND METHODS
Specimens examined are deposited in the following herbaria: COL, HUA, JAUM, and MEDEL (abbreviations following Holmgren & al., 1990, Index Herbariorum).Isotypes of the new species will be distributed to HUA, MA, and NY.The photographs that illustrate the new species were taken with a Canon EOS 7D digital camera.Measurements below 5 mm were taken using a Metric Mini Scale #1 by Electron Microscopy Sciences (EMS).

RESULTS AND DISCUSSION
While working on a taxonomic revision of the Colombian Burmeistera, we found several unidentified specimens collected in the department of Antioquia, mostly at the northern slopes of the Western Cordillera (including Las Orquídeas National Natural Park).These specimens with remarkably small flowers did not match any of the known species to date.
Etymology.The specific epithet refers to the size of the flowers, which corresponds to the smallest flower size of any known species in the genus Burmeistera.
Burmeistera minutiflora is easily distinguished by the bicolor (bright red and yellow) and the small corollas (<1.1 cm long), the smallest of the genus.Overall, it is similar to B. antioquensis Garzón & J.M. Vélez (Garzón & al., 2012, in press), but the corolla alone is similar to that of B. kirkbridei Wilbur, from Panama.However, the latter species falls into sect.Imberbes, as the apex of the two ventral anthers does not possess a tuft of apical hairs.The key below summarizes the main differences between the species with corolla tube < 1 cm from Costa Rica, Panama, Colombia, and Ecuador.
Distribution and ecology.With 23 species of Burmeistera (Idárraga, 2011), plus the recently described new species (Garzón & al., 2012), Antioquia is most likely the department of Colombia with the highest diversity of the genus.B. minutiflora has been collected in elevations between 2800-3550 m, in some of the few remnants of paramo and subparamo existing in the department.The localities where the new species has been collected fall into the superhumid paramo ecosystems, corresponding to the bp-M category, following Espinal (2011).The species could be under critical threat, because of the narrow distribution in fragile habitats that undergoes continuous fragmentation and destruction.
The species has been collected in flower in September, and in flower and fruit in February, April and November, which indicates that it has a long flowering season.Another interesting issue for discussion is the type of pollination of the new species.There is an overwhelming dominance of species of Burmeistera visited by bats and hummingbirds (Muchhala, 2006) with a considerable amount of variation in traits like the length and color of the corolla tube and lobes, odor, and the stigma exertion, being the width of the corolla aperture the most critical for pollinator specialization.The reduction observed in corolla sizes in B. minutiflora strongly precludes that most of possible visitors in other species could act as effective Burmeistera minutiflora, a new species from Colombia pollinators.Instead, the display of the yellow lobes and stigma as well as the narrow corolla aperture suggests an evolution towards an entomophilous pollination syndrome, yet undescribed for this genus.
KEY FOR THE SPECIES OF BURMEISTERA WITH COROLLA TUBE < 1 CM LONG.

Fig. 1 .
Fig. 1.Burmeistera minutiflora.A, B, plant in its natural habitat; C, detail of a flowering shoot; note resupination from flower four (arrow) onwards; D, E, flower in lateral (D), and frontal (E) views.Scale bars = 5 mm (All from the holotype).