Garagoa miconia (Miconia garagoana), rheophytic species from Andean riparian at 2100 meters of Colombia

NEWS - A new species, Garagoa miconia (Miconia garagoana), from riparian habitats in the northern Cordillera Oriental of Colombia, is the second species in rheophytic condition in the Colombian Andean forests and is characterized by stellate-lepidote trichomes, terminal inflorescences, 4-merous flowers, oblong-subulate anthers with apical pores and a 2-locular ovary.

The new species is so far only known from Colombia and the researchers propose Critically Endangered (CR). Differences with other rheophytic species in Colombia are noted and it is argued that this species is related to other Andean species with bluish-green ripe fruits such as M. squamulosa and M. symplocoidea.

M. garagoana shows distinctive morphological characteristics, recognized by its rheophytic condition and abundant branching, sometimes with plagiotropic main branches that lean under the influence of water currents. The species has stellate-lepidote trichome indumentum on distal branches, inflorescences and undersides of leaves.

Linear elliptical leaves are a distinguishing feature of the species inhabiting riverbanks and tributaries as an adaptation to withstand constant water flow. Other remarkable features include terminal inflorescences with few flowers (1-14), predominantly 4 flowers, oblong-subulate anthers with ventrally oriented pores and a 2-loculated ovary. Ripe fruits are bluish green and seeds are large and less than 20.

M. garagoana is similar to M. riparia and M. rheophytica, but grows below 1000 m elevation (vs. 2100 m in M. garagoana). Vegetatively similar to M. riparia, but has a deep red indumentum of pinoid trichomes on the stems (vs. stellate-lepidotes in M. garagoana), 5-merous flowers (vs. predominantly 4-merous) and dark purple or black fruits (vs. bluish green).

Similar to M. rheophytica, but this species has branches with a dense red indumentum of dendritic trichomes, ciliated leaf margins, dichasial axillary inflorescences, 5-merous flowers, yellow anthers, 3-locular ovaries, globose-subglobe fruits with bright indigo blue color and ovoid seeds with lateral symmetry planes and elliptical to elliptical-ovate antiraphal.

Based on the number of petals, M. garagoana can be attributed to the Ulmarioides complex. However, all species of this complex always have a 4-locular ovary and bright red or fuchsia anthers, so there is no complete certainty.

Probably the most closely related M. squamulosa (Sm.) Triana and M. symplocoidea Triana, since they share the stellate-lepidote trichome indumentum on the vegetative parts and flowers, the shape of the stamens and especially the bluish-green ripe fruits with angular ovoid seeds with a smooth testa.

The rheophytic condition is one of the characteristics of M. garagoana, which is resistant to flooding, which is limited to the beds of fast-flowing rivers and tributaries, growing there up to the flood level, but not beyond the reach of flash floods that occur regularly.

Melastomataceae has about 23 species of rheophytes, among which M. linearis (Gleason) Michelang, M. mulleola Wurdack, M. rheophytica, M. riparia and M. salicina (Ser. ex DC.) Mabb. However, there is a gap in information regarding the habitat, so it is not known for certain. On the other hand, some species recorded as rheophytes are not exclusive to riparian environments like M. mulleola.

In Santander, M. garagoana flowers in November, while in Boyacá it flowers between February and July. Fruiting occurs between April and August. At least in the Boyacá area, active flowering and fruiting events are thought to occur almost throughout the year.

The new species is endemic to Colombia in the Northern Eastern Cordillera, in relatively undisturbed Andean forests at elevations of 2000-2200 meters and usually on moderate to steep slopes with remnants of riparian vegetation in moist forests within a matrix of pastures for livestock grazing. The specific epithet refers to the municipality of Garagoa.

Original research

Mendoza-Cifuentes H, Ariza-Cortés W, Carvajal Rojas L (2024). Miconia garagoana - Melastomataceae: A new rheophytic species from the eastern Andes of Colombia. PhytoKeys 247: 145-154, DOI:10.3897/phytokeys.247.119563

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