Begonia vasconcelosiana L.Kollmann, 2020

Kollmann, Ludovic Jean Charles, 2020, NOVELTIES IN BRAZILIAN BEGONIACEAE II: a new species from Minas Gerais, Phytotaxa 437 (3), pp. 156-160 : 156-160

Begonia vasconcelosiana L.Kollmann , sp. nov. § Pritzelia ( Figs. 1 , 2 , 3).

Begonia vasconcelosiana is closely related to Begonia lealii Brade (1954: 81) in its peltate leaves, stellate trichomes, persistent stipules and bracts, and having prophylls, but can be distinguished from B. lealii by the petioles being 1.2–7.5 cm long (vs. 1–2 cm), the inflorescence being 15–35 cm long (vs. 4–7 cm), bracts 3–6.5 × 1.2–3 mm (vs. 8–10 × 3–4 mm), the largest wing on the capsule being 8–9 mm and ascendant (vs. 1–2 mm long and not ascendant) and the other two wings being 5–7 mm long (vs. 1 mm); also the internodes are much more congested in B. vasconcelosiana (to 1 cm long) than in B. lealii (to 5 cm long).

Type:— BRAZIL. Minas Gerais: Alvarenga, Pico da Aliança, 18 April 2018, (fl., fr.), L.Kollmann 13500 [cultivated specimen with alcohol material](holotype MBML!).

Description:—Herbs erect, 15–20 cm high, with an arachnoid indumentum of stellate trichomes ca. 0.8 mm long, 4-branched at the apex. Stems 0.7–0.9 cm diam., internodes 0.2–1 cm long, green to reddish, brown at maturity. Stipules, 4–9 × 2–4.5 mm, ovate, apex acute, margins entire, persistent, with scattered stellate hairs abaxially. Petioles 1.2–7.5 cm long, red, pilose with stellate trichomes.. Leaf blades 2–5.3 × 1.2–3 cm, asymmetric, peltate, ovate-lanceolate to oval, dark green, adaxial surface appearing grey due to the trichomes, abaxial surface glabrescent, appearing brown due to the trichomes when young, red when old, apex obtuse to acute, base rounded, margin entire, hydathodes present, veins actinodromous, 6–7 veins at base. Inflorescences 15–35 cm long, 4 dichasial cymes, reddish, pilose; bracts persistent, 3–6.5 × 1.2–3 mm, triangular, apex acute, reddish, pilose with stellate trichomes. Staminate flowers: pedicels 8–10 mm long, reddish, pilose with stellate trichomes; sepals 2, ca. 9 × 8 mm, rounded to ovate, apex obtuse to rounded, margins entire, white, base slightly reddish, pilose with stellate trichomes abaxially; petals 2, ca. 7 × 3 mm, white, concave, elliptic, apex obtuse, margins entire, glabrous; stamens 6–7, yellow, filaments equal, ca. 1 mm long, anthers ca. 2 × 1 mm, oblong, with longitudinal slits, connective slightly projecting, apex rounded. Pistillate flowers: pedicels 9–10 mm long, reddish, pilose with stellate trichomes; prophylls 2, 3–3.2 × 0.7–1 mm, at the apex of the pedicel, elliptic, apex acute, deciduous, pilose, sepals 2, 8–11 × 7–9.5 mm, ovate, apex obtuse to acute, white, base slightly reddish, pilose with stellate trichomes abaxially; petals 3, glabrous, white, unequal, one ca. 10 × 4.5 mm, elliptical, apex obtuse, the other two 7.5–10 × 6–8.5 mm, obovate to ovate, apex rounded to obtuse; ovary 3-locular, placentation axile, one placenta per locule; 3 styles, ca. 3 × 2 mm, yellow, united at base, each trifurcate, entirely covered with stigmatic papillae. Capsules 0.8–1.0 × 0.5–0.6 cm, basally dehiscent, pedicels 0.8–1 cm long, 3-winged, wings unequal, the largest one ca. 1.1 × 0.8–0.9 cm, ascendant, apex rounded, smaller two 0.8–0.9 × 0.5–0.7 cm, ascendant, apex rounded, Seeds ca. 0.4 × 0.2 mm, oblong, apex rounded.

Additional specimen examined (paratype):— BRAZIL. Minas Gerais: Alvarenga, Pico da Aliança, 11 july 2013, (fl.), L.Kollmann 12878 [cultivated specimen] (MBML!).

Distribution, habitat and phenology: — Begonia vasconcelosiana is known only from Pico da Aliança ( Fig. 3), an inselberg of south-eastern Minas Gerais state, at 900 to 1430 m elevation, in campos rupestres, which are areas of open vegetation on rocky to sandy soils. Begonia vasconcelosiana grow in rocks crevices in sunny places. Flowers were observed from December to June, fruits from February to September.

Conservation status: —Due to the apparent endemic distribution of Begonia vasconcelosiana , with an Area of Occupancy estimated to be less than 4 km 2 and considering the high deforestation, fire and land use changes it would seem prudent to include this species in the Critically Endangered category CR (B2ab(iii)) due to the one known location and decline in quality of habitat ( IUCN 2017).

Etymology: —The name of the new species honors Reginaldo de Vasconcelos Leitão, an orchid enthusiast who found this new species. Reginaldo has contributed to the knowledge of the flora of south-eastern Minas Gerais and discovered some new species of Droseraceae , Orchidaceae , Bromeliaceae and now Begoniaceae .

Notes: —According to the sectional classification of Doorenbos et al. (1998) and Moonlight et al. (2018), Begonia vasconcelosiana belongs to Begonia section Pritzelia , which has approximately 150 species from South America. The species in this section share entire placentae and the presence of cystoliths in leaf cells ( Doorenbos et al. 1998).

Figures

FIGURE 1. Begonia vasconcelosiana. A. Habitat; B. Habit in cultivation, C. Stem; D. Leaf; E. Male flowers; F. Immature fruit. A, Photo R.Vasconcelos; B, C, D, E, F, Photos L.Kollmann

FIGURE 2. Begonia vasconcelosiana. A. Habit; B. Trichome; C. Stipule; D. Bract; E. Sepals (a) and petals (b) of male flower; F. Stamen; G. Sepals (a) and petals (b) of female flower; H. Stigma; I. Fruit; J. Prophyll; K. Seed. Illustration by L. Kollmann from L. Kollmann 13500.