Begonia pedrabrancensis E.L.Jacques, 2022

Jacques, Eliane De Lima, 2022, Three Brazilian species of Begonia (Begoniaceae) from the state of Rio de Janeiro, Brazil, Phytotaxa 561 (2), pp. 138-150 : 146

Begonia pedrabrancensis E.L.Jacques , sp. nov. ( Figs. 7 , 8 , 9 )

Begonia pedrabrancensis is most similar to B. bidentata Raddi but differs in having glabrous internodes, abaxial leaf blades and petioles (vs. puberulous, with simple trichomes); dentate margins to its leaf blades (vs. biserrate); and involute wings on its ovary and fruits (vs. flat).

Type:— BRAZIL. Rio de Janeiro: Fiocruz Mata Atlântica , 22º56’35.8”S, 43º24’56.4”W, 79m elevation, 31 January 2022, E. L. Jacques 2070 et J. P. Costa (holotype RBR 56200!, isotype RB!) .

Subshrub, erect, delicate, rupicolous, ca. 40 cm tall, glabrous to microscopic glandular trichomes. Cystoliths present, best seen in hyaline structures. Stems erect, internodes 1–1.6 cm long, vinaceous, with microscopic glandular to glabrescent. Stipules inconspicuous, persistent, ca. 5 × 0.5–1 mm, triangular, apex setiferous, margins entire, glabrous, subcarnose when fresh, scarious when dry. Leaves simple, petioles 0.5–1 cm long, vinaceous to pinkish, glabrous, leaf blades basifixed, (8.3–)9.9–13 × (1.6–) 1.9–2.3 cm, entire, lanceolate, inconspicuously asymmetrical, carnosus, base obtuse, margins dentate, apex acuminate, adaxial surface glabrous, shiny green, abaxial surface glabrous, vinaceous to dark vinaceous on the veins, venation craspedodromous, 6 pairs of alternated secondary veins. Inflorescence in 4- branched cymes, bearing up to 4 flowers because of temporal dioecy, 3–4 cm long (including the rachis), up to 4 cm long when fruiting, rachis (1.8–) 2.4–2.8 cm long (up to same size when fruiting), glabrous, reddish on basal portions to pinkish distally. Bracts persistent, 1–2.5 × ca. 0.5 mm, triangular, apex setiferous, margins entire, glabrous. Staminate flower: pedicels ca. 10 mm long, white to pinkish, glabrous, tepals 4, external pair 6–7 × ca. 3 mm, ovate, apex acute, margins entire, white, membranaceous, with microscopic glandular trichome on dorsal surface, internal pair ca. 4 × 1.5–2 mm, elliptic, apex acute, margins entire, white, membranaceous, glabrous, stamens ca. 17, ca. 2.5 mm long, filaments ca. 0.5 mm long, free, connective projecting, obtuse to truncate, anthers ca. 2 mm long (including connective), oblong, extrorse, yellow. Pistillate flower: pedicels ca. 2 mm long, pinkish, glabrous, bracteoles 2, persistent, located alternately on the pedicel, triangular, 1.5–2 × ca. 0.3 mm, white-pinkish, tepals 5, white, unequal, 4 largest, 4–5 × 1–2 mm, 1 smallest, ca. 3 × 0.5 mm, lanceolate, apex acuminate, margins entire, membranaceous, with microscopic glandular trichomes on dorsal surface, ovary 3-locular, ca. 5 × 3 mm, white, microscopic glandular trichomes, wings ca. 1.5 mm wide, equal, involute, pinkish, placentae entire, stigmas 3, ca. 2.5 mm long, bifurcate, branches spiraled, yellow. Capsule 11–14 × 8–9 mm (including wings), basally dehiscent, glabrous, light brown when mature, elliptic, peduncles 2–4 mm long, glabrous, brown, wings 3, equal, involute, rounded, 10–12 × ca. 3 mm, locular region ca. 12 × 3 mm, ovate, glabrous, seeds oblong.

Etymology:—The specific epithet refers to name of the type locality, Parque Estadual da Pedra Branca.

Phenology: —Flowering and fruiting December to February.

Distribution and ecology: —This species is known only from the typical locality, Parque Estadual da Pedra Branca, in the municipality of Rio de Janeiro, metropolitan region of the state of Rio de Janeiro, in an area that constitutes the buffer zones of the conservation unit, belonging to FioCruz Mata Atlântica. The buffer zone favors the maintenance of natural resources and minimizes the negative environmental impacts on the conservation unit, especially in this one that is very close to intensely urbanized places. Begonia pedrabrancensis is known from one population, with around 60 individuals in an area of 8 m ². It grows in submontane forests, on a stones wall covered by a thick layer of leaf litter, in a shady and very humid place, at an altitude of about 70 m.

Provisional conservation assessment:— B. pedrabrancensis is provisionally assessed as Critically Endangered (CR B2ab(iii,v)) under IUCN Red List criteria ( IUCN Standards and Petitions Committee, 2019), due to being known in only one locality, close to intensely urbanized places, very small population and is subject to various threats such as wildfires, invasive species and a decline in the quality of its habit.

Additional specimen examined (paratype): — BRAZIL. Rio de Janeiro: Fiocruz Mata Atlântica, cultivated in the Botanical Garden of Universidade Federal Rural do Rio de Janeiro, 10 December 2021, E. L. Jacques 2067 ( RBR 56201!, RB!) .

Taxonomic notes:— Begonia pedrabrancensis is a delicate subshrub, ca. 40 cm tall, glabrous or with microscopic glandular trichomes. It can be easily recognized by its subsymmetrical, lanceolate leaf blades, craspedodromous venation, few-flowered inflorescences, 4-branched cyme, staminate flowers with ovate external tepals, with microscopic glandular trichomes on the dorsal surface, elliptical and glabrous internal tepals, pistillate flowers with 5 unequal tepals, lanceolate, with microscopic glandular trichomes on dorsal surface and elliptical capsules, with 3 equal and involute wings. Begonia pedrabrancensis is similar to B. bidentata Raddi (1820: 408) and B. stenophylla A.DC. (1859: 137) which shares the shape and venation of its leaf blades. Begonia pedrabrancensis is similar to B. bidentata in its subshrub habit, glabrous stems and stipules, and the small size of its flowers, hidden beneath the leaves. However, B. pedrabrancensis differs from B. bidentata by having internodes with microscopic glandular trichomes to glabrescent, glabrous petioles and abaxial leaf surfaces (vs. puberulous, with simple trichomes), dentate margins of leaf blades (vs. biserrate), persistent stipules (vs. caducous), involute wings of ovary and fruits (vs. flat), glabrous capsules, with rounded superior margins (vs. puberulous, with straight superior margins). Begonia pedrabrancensis can be easily distinguished from B. stenophylla by its glabrous abaxial leaf surface (vs. ferrugineous, tomentose) and its capsule with equal and involute wings (vs. subequal, flat).

Figures

FIGURE 7. A–M. Begonia pedrabrancensis E.L.Jacques. A, Habit, showing inflorescence and infructescence; B–C, Details of pedicels of pistillate flowers, showing bracteoles; D, Detail of distal portion of stems, showing base of leaf blades; E, Margins of leaf; F, Staminate flowers, buds; G, Staminate flowers, front view; H, Staminate flowers, showing the androecium; I, Stamen; J–L, Pistillate flowers, different periods of anthesis; M, Capsule. Illustration by Maria Alice Rezende from E.L. Jacques et al. 2070 (A–D, F, H), E.L. Jacques et al. 2067 (E, G).

FIGURE 8. A–H. Begonia pedrabrancensis E.L.Jacques. A, Habitat; B, Habit; C, Branch, showing abaxial leaf surface; D, Branch, showing adaxial leaf surface; E, Staminate flowers; F, Branch, showing pistillate flowers; G, Pistillate flowers; H, Immature fruits. (A–H from E.L. Jacques et al. 2070 (A= 5 cm; B= 6 cm; C= 1.8 cm; D= 1.8 cm; E= 7 mm; F= 10 mm, G= 10 mm, H, 7 mm). A–H Photos E.L. Jacques

FIGURE 9. Distribution map of Begonia pedrabrancensis (rhombus).