Begonia piranga L. Kollmann & Gonella, 2021

Kollmann, Ludovic Jean Charles & Gonella, Paulo Minatel, 2021, Novelties in Begonia (Begoniaceae) from the campos rupestres of Serra do Padre Ângelo, Minas Gerais, Brazil: a new species and a new record, Phytotaxa 510 (1), pp. 69-77 : 70-74

Begonia piranga L. Kollmann & Gonella , sp. nov. ( Figs. 1 , 2 , 3 ).

Begonia piranga is closely related to Begonia ruhlandiana Irmscher (1953: 67) with which it shares stellate trichomes, craspedodromous venation, deciduous stipules and bracts, pistillate flowers with prophylls and ovary with one placenta per locule. However, B. piranga is easily distinguished by having red flowers (vs. white to pink); staminate flowers with abaxially densely pilose sepals (vs. glabrescent), ovate sepals, 0.75–1.05 × 0.6–0.9 cm (vs. orbiculate sepals, 0.5–0.7 × 0.47–0.6 cm), petals 2 (vs. petals absent); pistillate flowers with a pilose ovary (vs. glabrescent); capsules 0.9–1 × 0.3–0.4 cm (vs. ca. 0.5 × 0.3–0.4 cm), and fruit wings 6–12 mm wide (vs. 1–4 mm).

Holotype:— BRAZIL. Minas Gerais: Conselheiro Pena, Serra do Padre Ângelo, Pico do Padre Ângelo , no platô do topo do pico, campo rupestre, 19°19’12.78”S 41°34’42.02”W, 1500 m, 30 November 2020, P. M. Gonella & D. P. Cordeiro 1824 ( MBML).

Description:—Perennial subshrub, erect, up to 1.5 m tall, pilose, densely lanate to lanuginose; indumentum consisting of stellate trichomes, 4–6 branched at the apex, ferruginous when fresh and white when mature, present on stem, leaves, and inflorescence parts. Stems 0.45–0.75 cm diam., internodes 0.4–5.6 cm long, green to red, brown when mature, densely pilose. Stipules lanceolate, 1–1.5 × 0.4–0.7 cm, red, apex acute, margins entire, deciduous, adaxial surface glabrous, densely pilose on the abaxial surface. Petioles 1.2–1.3 cm long, red, densely pilose. Leaf blades ovate, 5.8–6.5 × 3.5–4.3 cm, conduplicate, succulent, chartaceous when dry, adaxial surface green, shiny, glabrescent, abaxial surface densely pilose, apex obtuse, base oblique, margin entire, hydathodes present, venation craspedodromous. Inflorescences 19–63 cm long, 3–4 dichasial cymes, red, densely pilose. Bracts elliptic, 0.7–2 × 0.9– 0.2 cm, reddish, deciduous, apex acute, densely pilose on the abaxial surface, carinate. Staminate flowers: pedicel 3–4 mm long, red, densely pilose; sepals 2, ovate to elliptic, 0.75–1.05 × 0.6–0.9 cm, cinnabar red, apex obtuse, margins entire, densely pilose on the abaxial surface; petals 2, obovate to elliptic, 0.5–0.83 × 0.2–0.5 cm, red carmine, apex obtuse, margins entire, slightly pilose on the abaxial surface; stamens ca. 20, ca. 2 mm long, yellow, filaments subequal, ca. 0.7 mm long, anthers ca. 1.3 mm, rimose, ovate, connective slightly projecting, apex rounded. Pistillate flowers: pedicels ca. 0.7 cm long, red, densely pilose; prophylls (1–)2, elliptical to ovate, 0.6–0.75 × 0.35–0.5 cm, persistent, at the base of the ovary, apex obtuse to acute, densely pilose on the abaxial surface; sepals 2, elliptical, 0.6–1.2 × 0.4–0.9 cm, carmine red to magenta, apex obtuse, densely pilose on the abaxial surface; petals 3, elliptical to oblanceolate, 3.2–8 × 3–4.5 mm, carmine to pink-whitish, apex obtuse to rounded, slightly pilose on the abaxial surface; ovary 3-locular, placentation axile, one placenta per locule, apex of the placenta slightly divided; styles 3, ca. 3 mm long, yellow, united at base, each bifurcate, entirely covered with stigmatic papillae. Capsule 0.9–1 × 0.3–0.4 cm, basally dehiscent, covered by trichomes, peduncles 0.8–1 cm long, covered by trichomes, wings 3, unequal, covered by trichomes, the largest one ca. 1.6–1.7 × 0.7–1.2 cm, slightly ascendant to straight, apex rounded to acute, the two smallest ones 0.7–1.2 × 0.6–1 cm, descendant, apex rounded. Seeds ca. 0.25–0.35 × 0.2 mm, oblong, apex rounded.

Additional specimens examined (paratypes):— BRAZIL. Minas Gerais: Conselheiro Pena: Serra do Padre Ângelo, Pico do Padre Ângelo , no platô do topo do pico, campo rupestre, 19°19’6.9”S 41°34’43.8”W, 1500 m, 04 December 2018, P. M . Gonella , A . Fleischmann , L . Medeiros & L . França 1087 ( MBML); ibid, 21 August 2020, P. M . Gonella , E . Ramos , D. P . Cordeiro , T. H . Condez & P. R . Bartholomay 1542 ( MBML, RB) .

Distribution and habitat: — Begonia piranga is endemic to Pico do Padre Ângelo, the second highest peak of Serra do Padre Ângelo (Conselheiro Pena, Minas Gerais), where it can be found on the top plateau at elevations around 1500 m ( Fig. 1 ). The species grows in campos rupestres, being found on pockets of sandy soil accumulated between large quartzitic rocks, on sites exposed to direct sunlight ( Fig. 2A–C ). Only around 20 individuals of the species have been located in the area so far, all growing within a radius of 100 m.

Phenology:—The species was observed with flowers in February, May, and from August to December, suggesting a continuous flowering period.

Conservation status assessment:—Critically Endangered CR B2ab(iii) + D. Begonia piranga has an AOO of 4 km 2 (criterion B2), is known from a single location (sub-criterion B2a), with approximately twenty mature individuals (criterion D). This species is subject to several threats such as invasive species, wildfires, climate change, and unregulated tourism that can lead to poaching and aggravation of invasion by alien species, all of which leading to a decline in habitat quality (sub-criterion B2b(iii)). The threats to which the species is subject are thoroughly described for other endemic species of the area in Gonella et al. (2015), Andrino & Gonella (2021), and Antar et al. (2021a, 2021b). The Serra do Padre Ângelo and other areas of campos rupestres of the João Pinto Formation remain as some of the few natural areas in the region, which had most of its original vegetation converted into pastures ( Fig. 1 ). The recent wildfire of great proportions that affected the Serra in late September 2020 (see Andrino & Gonella 2021) also impacted this species, with at least two of the monitored individuals having disappeared after the fire. Large areas of the top plateau of Pico do Padre Ângelo that remained unexplored before the fire could also have harbored individuals of this species. Therefore, its conservation status is further aggravated by the extremely reduced population size, now estimated to be less than 20 known mature individuals. Based on its restricted occurrence, reduced population size, listed threats to which it is exposed which are leading to a decline in the quality of its habitat, and the fact that it is not found inside any protected area, B. piranga is provisionally assessed as Critically Endangered under the aforementioned IUCN Red List criteria ( IUCN 2012).

Etymology:—The red and showy flowers of this species are one of its most distinctive characters ( Fig. 2G–I ), hence we have chosen the epithet “ piranga ”, which means “red” in the Tupi-Guarani language ( Bueno 2008).

Notes:—According to the sectional classification of Doorenbos et al. (1998), B. piranga belongs to B. sect. Pritzelia , a section with approximately 150 species from South America, characterized by the entire placentae and presence of cystoliths in the leaf cells ( Doorenbos et al. 1998).According to the sectional classification of Moonlight et al. (2018), B. piranga belongs to B. sect Tetrachia , a section with approximately 16 species from Brazil, characterized by the presence of stellate or peltate, scale-like hairs; frequently peltate leaves; axile, usually simple placentation; and cymose inflorescences.

Figures

FIGURE 1. Geographic distribution of Begonia piranga (white circle) and Begonia vasconcelosiana (white triangles) in eastern Minas Gerais, with land use projected over a satellite image and highlighting the limits of the only protected area of the region (Parque Estadual de Sete Salões). In the reference maps to the left, the yellow shape represents the area of the Legal Atlantic Forest.

FIGURE 2. Begonia piranga. A–B. Habitat; C. Habit; D–E. Detail of stem and leaves; F. Detail of an emerging inflorescence and its bracts; G. Male flowers; H. Female flower front view; I. Female flowers, lateral view. Photos P.M. Gonella.

FIGURE 3. Begonia piranga. A. Habit; B. Detail of indumentum on the stem; C. Stipule; D. Leaf; E. Detail of indumentum on the abaxial leaf surface; F. Detail of leaf margin; G. Bract; H. Prophyll; I. Male flower; J. Dissected male flower, highlighting sepals (a) and petal (b); K. Stamens in front and dorsal view (left and right); L. Female flower, lateral view; M. Female flower, front view; N. Dissected female flower, highlighting sepals (a), and petals (b); O. Stigma; P. Capsule, lateral view; Q. Seed. Illustration by Joelcio Freitas based on the holotype.