Begonia lorenzii E.L.Jacques, 2020

Jacques, Eliane De Lima, 2020, Two new Brazilian species of Begonia (Begoniaceae) from Atlantic Coastal Forest, Phytotaxa 432 (1), pp. 38-46 : 39-42

Begonia lorenzii E.L.Jacques , sp. nov. ( Figs. 4 , 5 , 6 )

Begonia lorenzii is most similar to B. windischii L.B.Sm. ex S.F.Sm. & Wassh. but differs by stems with villous indumentum (vs. glabrous), triangular stipules, ca. 1–1.5 × 0.5 cm (vs. ovate, 2–3 × 1–2 cm) and leaves with ciliate margins (vs. crenate).

Type:— BRASIL. Rio de Janeiro: Paraty, estrada Paraty-Cunha, 23°12´61.3¨ S, 44°47´95.4¨ W, 15 August 2012, Jacques, Lorenzii et al 1851 (holotype RBR!, isotype RB!).

Description:—Herbs, erect, terrestrial, ca. 20–30 cm tall, villous. Cystoliths absent. Stem erect, with internodes green to reddish, 1–2.5 (–5) cm long, villous. Stipules persistent, triangular, ca. 1–1.5 × 0.5 cm, with a crest of trichomes on the principal vein, scarious, greenish to brown, apex acute, margins ciliate. Leaves simple, petioles terete, greenish to pink, 3–13 cm long, villous, with simple trichomes along the entire length, leaf blades basifixed, slightly lobate, asymmetrical, transversely ovate, papyraceous, 10.5–15 × 5.5–6.5 cm, both surfaces villous, trichomes pink to white, margins ciliate, apex acuminate, base cordate, venation actinodromous, veins 5–6. Inflorescence 2-branched cyme, ca. 7 cm long, rachis greenish-white, ca. 3.5 cm long (up to ca. 4 cm long when fruiting), bracts persistent, greenish-white, ca. 7 mm long. Male flowers ca. 11 mm long, pedicels greenish, ca. 5 mm long, villous; tepals 4, external pairs white, ovate, 8–14 × 5–13 mm, apex obtuse to rounded, villous, simple trichomes and scales reddish, internal pairs white, elliptic, 6–9 mm × 3–3.9 mm, glabrous, stamens ca. 25, free, ca. 3 mm long, anthers yellow, elliptic, ca. 2 mm long (including connective), rimose, with frontal openings, extrorse, filaments ca. 1 mm long. Female flowers ca. 28 mm long, pedicels pink, ca. 13 mm long, villous, trichomes reddish, bracteole 1, persistent, located at pedicel, ovate, inconspicuous, ca. 1 mm long, tepals 3, white, ovate to widely ovate, 10–14 × 7–11 mm, villous, trichomes simple to 2-branched, reddish, ovary 3–locular, stigmas 3, branches spiraled, yellow, ca. 3 mm long, ovary pink, trichomes reddish, ca. 10 × 10 mm (including the wings), villous, placentae entire. Capsules 24–25 × 23–27 mm (including the wings), sparsely villous, apex truncate, peduncles 20–26 mm long, wings brown, villous, subequal, the largest one with obtuse apex, locular region elliptic, 15–17 × 6 mm, brown, villous, seeds oblong.

Etymology:—The specific epithet honors Harri Lorenzi, agronomist and botanist of the Jardim Botânico Plantarum, for his input to the study of flora of Brazil and to the ex-situ conservation of Brazilian Begonia species.

Phenology: —Flowering and fruiting in August.

Distribution and ecology: — Begonia lorenzii is known only from the type locality, the Paraty-Cunha road, in the municipality of Paraty, southern region of Rio de Janeiro state, Brazil. This species inhabits in submontane forests, in shady localities, at elevation of 340 to 400 m asl. It grows in a place with many other rupicolous Begonia species, and it was observed in a population of only four to five individuals. Accordingly, B. lorenzii is provisionally assessed as Vulnerable (VU D2) under IUCN Red List criteria.

Taxonomic notes:— Begonia lorenzii can be easily recognized by having villous stems, leaf blades slightly lobate, transversely ovate, 10.5–15 × 5.5–6.5 cm, villous on both surfaces, ciliate at the margin, few-flowered inflorescence, 2-branched cyme, female flowers with one, persistent, inconspicuous bracteole, pistillate flowers with three tepals and capsule sparsely villous, truncate at the apex. Begonia lorenzii resembles B. windischii Smith et al. (1999: 27) , which is endemic to São Paulo state, by the shape of the leaves, inflorescence with few flowers, three tepals in the pistillate flowers and shape of capsulae, however B. windishii is a rupicolous herb (vs. terrestrial), with a repent, glabrous stem (vs. erect, villous), leaves with crenate margins (vs. ciliate), with prominent veins and larger stipules 2–3 × 1–2 cm (vs. 1–1.5 × 0.5 cm).

Figures

FIGURE 4. A–F. Begonia lorenzii E.L.Jacques. A, Habitat; B, Flowering plant showing inflorescence with female flowers; C, Flowering plant showing inflorescence with male and female flowers; D, Flowering plant showing details of the ovary (A–D from E.L. Jacques et al. 1851). (A= 8 cm; B= 3.5 cm; C= 1.5 cm; D= 2.5 mm). Photos H. Lorenzi.

FIGURE 5. A–F. Begonia lorenzii E.L.Jacques. A, Male flower showing the indumentum of tepals; B, Male flower, lateral view; C, Male flower, front view; D, Female flower; E, Ovary in cross section; F, Capsule (A–F from E.L. Jacques et al. 1851). (squares= 10 mm). Photos H. Lorenzi.

FIGURE 6. Distribution map of Begonia lorenzii E.L.Jacques (circle). Green shading indicates the limits of the Serra da Bocaina National Park.