Begonia margaretiana Handro ex L. Kollmann 2020, sp. nov.
Creators: name: Kollmann, Ludovic Jean Charles
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia margaretiana

description: Begonia margaretiana Handro ex L.Kollmann sp. nov. (Figs. 1, 2, 3)
Begonia margaretiana is closely related to Begonia paulensis de Candolle (1859:125) but can be distinguished by erect plant vs. rhizomatous, stipules falcate vs. triangular, leaves not peltate vs. peltate, larger capsule wing 1.4–2 cm vs. 2–2.5 cm wide, capsule glabrous vs. strigose.
Type: — BRAZIL. Rio de Janeiro: Paraty, estrada Paraty-Cunha, 1500m elevation, 16 March 2019, L. Kollmann & H. Lorenzi 13588 (holotype MBML!; isotype HPL!).
Description: — Herbs erect to decumbent when old, 30–70 cm high, with scales, scales reddish with long hairs at the apex of the smaller scales and at the apex and margins of the larger scales. Stems: internodes 1–6 cm long, with scales. Stipules 1.6–3 × 0.5–2 cm, white, translucent, falcate, navicular, apex long-mucronate, with brown scales on the crest on the abaxial face, margins entire, deciduous. Petioles 6–9 cm long, brown to red, with scales, scales with long hairs prostrate on the petiole (resembling an arachnoid indument). Leaf blades 12.5–23 × 5.5–14 cm, asymmetrical, basifixed, obovate, lightly bullate on the adaxial face, dark green, red on the abaxial face with whitish veins, apex cuspidate, base cordate, lobes overlapping, margin dentate, lightly ciliate with hydathodes, venation actinodromous, with 5–8 veins at the base, with scales on the abaxial face. Inflorescences 5–16 cm long, ca.1 times dichasial, cymes with up to ca. 10 flowers staminate flowers and 2–4 pistillate flowers; bracts deciduous, 0.8–1.6 × 0.6–1.1 cm, green, ovate, glabrous, apex rounded to obtuse. Staminate flowers: pedicels ca. 7 mm long, green; sepals 2, 10–15 × 8–12 mm, white, orbicular, apex rounded, margins entire, strigose on abaxial face, trichomes green, base reddish; petals 2, 9–12 × 5–7 mm, white, obovate, glabrous, apex rounded, margins entire; stamens 30–32, yellow, filaments equal, ca. 1 mm long, anthers ca. 2.5 mm long, dehiscing via longitudinal slits, oblong, connective not projecting, apex rounded. Pistillate flowers: pedicels ca. 8 mm long, red; prophylls 2, 4–8 × 3–6 mm, green, translucent, like the bracts, ovate, apex obtuse; sepals 2, 1.3–1.4 × 1–1.1 cm, white, ovate to oblong, sparsely strigose, apex obtuse to rounded; petals 3, 1.5–1.7 × 0.5–1 cm, white, elliptical to obovate, sparsely hairy, apex obtuse; ovary 3-locular, one placentae per locule, placentation axile; styles 3, 4 mm long, 2 mm long branches and 2 mm long base, yellow, twisted, branches equal, united at base, 2-divided, covered with band of stigmatic papillae. Pedicels of fruits 1.6–2.5 cm long. Capsule 12–13 × 0.2–0.4 cm, basally dehiscent, glabrous, wings 3, unequal, the largest 1.4–2 × 1–2.6 cm, slightly ascendant to descendent, apex acute, the smaller two 1.5–1.7 × ca. 0.7 cm, lightly ascendant, apex obtuse to rounded. Seeds ca. 0.4 mm, oblong, apex rounded.
Additional specimens examined (paratypes):— BRAZIL, Rio de Janeiro: Paraty Municipality, Estrada para Cunha, 9 km of Paraty, 1968, M. Mee s.n. (SPF83851!); Paraty Municipality, Morro do Curalinho, 630m, 18 April 1994, R. Marquete 1689 (RB307352!); Morro do Corisco, 600m, 9 March 1994, S. Bennaroch 11 (RB308505!).
Distribution, habitat and phenology: — Begonia margaretiana occurs between 500–700 m elevation, on rocks in the forest. The predominant surrounding vegetation is Ombrophilous Dense Forest (Atlantic Forest). It flowers between January and May, fruits between April and May.
Conservation status: —Although part of the range of the new species is in a protected area, there are threats to the biodiversity of all parts of the Atlantic forest from illegal logging and harvesting of ornamental plants. Due to the apparent endemic distribution of B. margaretiana, the low number of specimens collected, its approximate EOO of 27 km 2, and its approximate AOO estimated at 12 km 2, it would seem prudent to assess the species as Endangered (EN), according to the IUCN (2017) criteria B2ab(i,ii,iii).
Etymology: —The name of the new species comes from a herbarium label in the Federal University of São Paulo [SPF83851]. This specimen is identified as Begonia margaretiana Handro, but Oswaldo Handro never published this name. Handro was a Brazilian botanist who described 6 new Begonia species, B. boraceiensis (1968:1), B. kautskyana (1981:1), B. odeteiantha (1969:4), B. peruibensis (1979:136), B. piresiana (1964:1), B. toledoana (1969:3) and a new variety B. inculta var. vestita (1968:3). Therefore, I have kept the name of the species that Handro gave in homage to Margaret Mee, a great botanical artist who produced hundreds of botanical paintings as a result of her exploration of the flora of Brazil.
Notes:—According to the sectional classification of Doorenbos et al (1998) and Moonlight et al (2018), Begonia margaretiana belongs to the section Pritzelia, a section with approximately 150 species from South America. Species of this section have entire placentae and have cystoliths in the leaf cells (Doorenbos et al. 1998).
description: Published as part of Kollmann, Ludovic Jean Charles, 2020, NOVELTIES IN BRAZILIAN BEGONIACEAE III: Begonia margaretiana, a new species from Rio de Janeiro state, pp. 72-76 in Phytotaxa 466 (1) on pages 72-75, DOI: 10.11646/phytotaxa.466.1.9, http://zenodo.org/record/13877762