Microlicia roseopetala R. B. Pacifico & Almeda 2024, sp. nov.
Creators: name: Pacifico, Ricardo
name: Almeda, Frank
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Melastomataceae
Microlicia
Microlicia roseopetala

description: Microlicia roseopetala R.B.Pacifico & Almeda, sp. nov. (Figs. 1, 2 D–E)
Type:— BRAZIL. Bahia: Miguel Calmon, Piemonte da Diamantina, trilha para a grota de Dona Antônia, ponto 200, 11°20’S, 40°31’W, 3 August 2006, fl., fr., D.C. Sousa, T. Nogueira, M.L. Guedes, R. de Valadão & M. Carvalho 53 (holotype: ALCB barcode ALCB070056!; isotype: CEPEC accession number 119228-online image!)
Diagnosis:— Microlicia roseopetala can be recognized by its petiolate leaves that are densely glandular-punctate and covered with eglandular trichomes 0.28–0.70 mm long on both surfaces, leaf blades 4.3–10.6 mm, elliptical to obovate, calyx lobes 2.0– 2.7 mm long that are oblong to triangular, magenta petals, and isomorphic stamens with thecae 1.4–1.6 mm long.
Openly-branched, erect shrubs 0.5–1.5 m tall. Branchlets quadrangular, densely glandular-punctate and covered with eglandular trichomes 0.28–0.70 mm long, the stem angles with inconspicuous wings ca. 0.1 mm wide, internodes 1.1–5.7 mm long. Leaves spreading, moderately ascendant (when dry), decussate, flat, not imbricate to subimbricate; petioles 1.0– 3.8 mm long, rectangular, dorso-ventrally flattened; blades 4.3–10.6 × 2.8–5.7 mm, elliptic to obovate, chartaceous, dull green and concolored (when fresh), becoming brownish (when dry), base attenuate, apex rounded to shortly acute, both surfaces densely glandular-punctate and covered with eglandular trichomes 0.28–0.70 mm long, margin entire and ciliate with similar trichomes, 1–3-nerved from the base, tertiary veins not evident. Flowers 5-merous, axillary, ebracteolate, solitary; pedicels 0.6–0.8 mm long; hypanthia (at anthesis) 1.8–2.6 mm long, 2.0– 2.6 mm wide at the torus, campanulate, brownish (when dry), densely glandular-punctate and covered with eglandular trichomes 0.28–0.70 mm long; calyx tubes 0.3–0.4 mm long; calyx lobes 2.0– 2.7 mm long, 0.7–1.0 mm wide at the base, oblong to triangular, brownish (when dry), apex shortly acute, externally like the hypanthia, margin entire, petals 4.6–6.6 × 2.6–3.4 mm, obovate, magenta, margins entire and glabrous, apex acuminate, both surfaces glabrous. Stamens 10, isomorphic; filaments 1.6–2.5 mm long, yellow, glabrous, thecae (excluding rostra) 1.4–1.6 × 0.4 mm, yellow, oblong, externally corrugated, polysporangiate, rostra 0.20–0.28 mm long, the ventrally inclined pores 0.16–0.18 mm wide, nearly circular, pedoconnectives 0.5–0.9 mm long, yellow, the appendages inconspicuous, ca. 0.13–0.17 mm long, apex truncate. Ovary (at anthesis) ca. 1.9 × 1.6 mm, superior, subglobose, glabrous, 3–4-locular; styles ca. 5.0 mm long, glabrous, sigmoid, stigma punctiform. Fruit at maturity an ovoid loculicidal capsule 2.4–3.1 × 1.9–2.3 mm, pale brown, ovoid, 3–4-valvate, enveloping hypanthia, rupturing and flaking away with age, dehiscent from the apex to the base (basipetal), columellas deciduous. Seeds 0.52–0.66 × 0.28–0.35 mm, yellow, reniform, testa foveolate, raphal zone 0.21–0.28 mm long, nearly circular.
Distribution, habitat and phenology:— Microlicia roseopetala appears to be endemic to the Parque Estadual das Sete Passagens in northeastern Bahia, Brazil (Fig. 3). It occurs in campo rupestre, exposed to full sun, at elevations between 1,100 –1,270 m. Microlicia roseopetala was collected flowering and fruiting in March, May, June and August.
Recognition:— Microlicia roseopetala differs from Microlicia leucopetala (Fig. 2. A–B) by its smaller flowers, with hypanthia 1.8–2.6 mm long (vs. 3.4–4 mm long in M. leucopetala), calyx lobes oblong to triangular (vs. subulate) that are shorter, 2.0– 2.7 mm long (vs. 3.7–5 mm long), magenta petals (vs. usually white) that are 4.6–6.6 mm long (vs. 8.5–10 mm long), and isomorphic stamens (vs. dimorphic) with thecae 1.4–1.6 mm long (vs. 2–3 mm long). Another possible relative is M. baccharoides (Fig. 2. C), from which it differs by its leaves 4.3–10.6 mm long (vs. 12–18 mm long in M. baccharoides), smaller flowers with hypanthia 1.8–2.6 mm long (vs. 4.5–5 mm long), magenta petals (vs. white) that are 4.6–6.6 mm long (vs. 9–12 mm long), isomorphic stamens (vs. dimorphic), and thecae 1.4–1.6 mm long (vs. 3–3.5 mm long).
Microlicia rotundifolia is also somewhat similar to M. roseopetala. The new species differs by having an indumentum of eglandular trichomes covering the branches, leaves, and hypanthia (vs. gland-tipped trichomes in M. rotundifolia), smaller flowers with hypanthia 1.8–2.6 mm long (vs. 4–5 mm long), petals 4.6–6.6 mm long (vs. 9–19 mm long), isomorphic stamens (vs. dimorphic), and thecae 1.4–1.6 mm long (vs. 2.5–4 mm long).
There is a significant distributional gap between M. roseopetala and the morphologically similar species mentioned above (Fig. 3). The rocky mountains of Parque Estadual das Sete Passagens are separated by approximately 180 km of lowland terrain from the central region of Chapada Diamantina, where M. baccharoides, M. leucopetala, and M. rotundifolia are found.
Etymology:— The epithet combines the Latin roseus (rosy/pink) and petalum (petal). It refers to the magenta petals of this species, a feature that can be used to differentiate M. roseopetala from its closest relatives (i.e. M. leucopetala and M. baccharoides typically have white petals).
Conservation: — The estimated EOO and AOO for M. roseopetala are 2,631 km ² and 8,000 km ², respectively. According to the IUCN (2019) criterion B, these values would support a Critically Endangered (CR) conservation status. All collected specimens are from PESP, where populations of M. roseopetala are also protected. To our knowledge, this is the second flowering plant species described as endemic to PESP, along with Sauvagesia insolita Queiroz-Lima & D.B.O.S.Cardoso in Queiroz-Lima et al. (2017: 60). According to INEMA (2024), gold mining is a major threat to PESP`s vegetation. We hope that the discovery of this new species highlights the importance of conducting additional fieldwork in PESP and protecting the northeastern section of the Chapada Diamantina.
Additional specimens examined (paratypes):— BRAZIL. Bahia: Miguel Calmon, trilha do Campo Limpo, 1,270 m, 7 May 2005, fl., fr., J.G. Freitas et al. 24 (HUEFS!); Piemonte da Chapada, 11°23'10’’S, 40°31'13”W, 1,169 m, 16 June 2006, fl., fr., J.S. Santos et al. 145 (ALCB, CEPEC-online image!); Piemonte da Chapada, 11°22'46’’S, 40°31'07”W, 1177 m, 17 June 2006, fl., fr., J.S. Santos et al. 146 (ALCB!). Miguel Calmon [“Senhor do Bonfim”], Mirante da Cachoeira do Urubu, 11°23'S, 40°31'W, [ca. 1,100 m], 7 May 2005, fl., fr., V.J. Santos 342 (HUEFS!); Cachoeira do Coração, 11°23'02’’S, 40°31'01”W, [ca. 1,100 m], fl., 12 March 2006, fl., fr., V.J. Santos 487 (HUEFS!).
description: Published as part of Pacifico, Ricardo & Almeda, Frank, 2024, Microlicia roseopetala (Melastomataceae: Lavoisiereae), a new species from the campo rupestre of Parque Estadual das Sete Passagens, Bahia, Brazil, pp. 256-262 in Phytotaxa 676 (3) on pages 257-261, DOI: 10.11646/phytotaxa.676.3.2, http://zenodo.org/record/14521830