Canastra glory bush (Pleroma canastrense) and viscous glory bush (Pleroma viscosa) from Serra da Canastra

NEWS - Canastra glory bush (Pleroma canastrense) and viscous glory bush (Pleroma viscosa) from Serra da Canastra National Park, Minas Gerais, Brazil, were established as new species that have stamens with short pediconnectives and inconspicuous ventral appendages.

P. canastrense has brown leaf blades, broadly ovate to rounded ovate, entire and depressed margins, with 11-17 basal acrodromous veins, stamens with short pediconnectives and inconspicuous ventral appendages along with white petals as distinguishing features from other Pleroma.

P. canastrense resembles P. wurdackianum (R.Romero & A.B.Martins) P.J.F.Guim. & Michelang and both have shrubby or shrubby habitats. However, P. wurdackianum has pink petals (vs. white in P. canastrense), hypanthium, and leaf blades with rounded glands (vs. glabrous).

P. canastrense is also similar to P. integerrimum (R.Romero & A.B.Martins) P.J.F.Guim. & Michelang. However, P. integerrimum differs in having brownish-green and uniform leaf blades (vs. brownish and colorless in P. canastrense), glabrous at the edges (vs. striated).

P. canastrense also resembles P. gertii. However, P. gertii has elliptical, elliptical-lanceolate or oblong to oblong-lanceolate leaves (vs. broadly elliptical to orbicular in P. canastrense) with 7-9 basal acrodromous veins (vs. 11-17) and purple petals (vs. white).

The plant flowers from April to August and fruits from June to October. The specific epithet refers to the restricted occurrence of this species in the Serra da Canastra hill area, where it is probably endemic. The beautiful population with white flowers is found only in campo rupestre with an area of occupancy of 48 km2.

Despite its restricted distribution in the Serra da Canastra, researchers propose it as "Least Concern" (LC) according to the IUCN category (2012, 2022) because most individuals are in a conservation unit with full federal protection established almost 50 years ago, without significant threats to the population.

P. viscosa has a thickening of younger branches, leaf blades, bracteoles, hypanthia and sepals caused by globular glands, prominent secondary veins on the abaxial surface of the leaf blade and stamens with very short pediconnectives (about 0.2 mm) as distinguishing features from other Pleroma species.

P. viscosa resembles P. gertii. However, P. viscosa has leaf blades covered with brownish glands (vs. yellowish green in P. gertii), which give a glutinous appearance especially on the adaxial surface (vs. not glutinous). Secondary veins are prominent on the abaxial surface of the leaf blade (vs. inconspicuous).

P. viscosa resembles Pleroma minus (R.Romero & A.B.Martins) P.J.F.Guim. & Michelang. However, P. minus has a glabrous or sparsely setose stem at the base (vs. rounded glands in P. viscosa), ascending leaves (vs. horizontal), smaller leaf blades 0.8-4.5 × 0.5-2.5 cm (vs. 2-8 × 3-6 cm), petioles about 2 mm (vs. 3.3-11 mm), petals rounded at the apex and ciliated at the margin (vs. rounded or slightly recessed, glabrous or slightly ciliated).

The plant flowers from January to July and fruits from April to October. The specific epithet refers to the lumpy appearance due to the rounded glands on the younger branches, on both sides of the leaf blade, bracteoles, hypanthium, and sepals.

P. viscosa is known only from the Serra da Canastra National Park, where it is probably endemic. Population in campo rupestre and area of occupancy of 32 km2. However, researchers proposed an initial category of “Least Concern” (LC) according to the IUCN (2012, 2022) because they did not identify a sustained decline in the occupancy of the P. viscosa population over the past 30 years.

Original research

Romero R, Pereira Silva R, Guimarães PJF (2024). Two new Pleroma species and an updated key: Melastomateae from the Serra da Canastra National Park, Minas Gerais, Brazil. PhytoKeys 247: 11-27, DOI:10.3897/phytokeys.247.130040

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