Begonia fimbritepala E.L.Jacques, 2020

Jacques, Eliane De Lima, 2020, Begonia fimbritepala (Begoniaceae), a new species endemic to the Atlantic Coastal Forest in the state of Rio de Janeiro, Brazil, Phytotaxa 439 (1), pp. 102-106 : 102-105

Begonia fimbritepala E.L.Jacques , sp. nov. ( Figs. 1 , 2 , 3 )

Begonia fimbritepala is most similar to B. olsoniae Smith & Schubert (1965: 250) but differs in having glabrous leaves on the adaxial surface, villous abaxial veins, with simple trichomes (vs. hispid on both surfaces, squamulose abaxial veins, fimbriate scales) and tepals with ciliate margins (vs entire to slightly crenulate).

Type:— BRAZIL. Rio de Janeiro: Miguel Pereira, Parque Municipal da Rocha Negra, antiga estrada de ferro de Miguel Pereira a Vassouras, 22°29´S, 43°31´W, 14 July 2013, Wängler 1383 (holotype RBR!, isotype, RB!).

Description:—Herbs, prostrate, rupicolous, ca. 10 cm tall (excluding the inflorescence), villous, with simple trichomes. Cystoliths absent. Stem prostrate, internodes ca. 0.5 cm long, reddish-green, villous. Stipules persistent, oblong, 2–2.5 (–4) × 1–1.5 cm, scarious, brown, apex aristate, margins entire, densely villous on the principal vein. Leaves simple, petioles terete, reddish, ca. 7–15 (–22) cm, densely villous along their entire length to glabrescent, with simple trichomes, leaf blades basifixed, entire, transversely ovate, asymmetrical, carnosus, 12–18 × 6–11 cm, adaxial surface greenish, glabrous, except by being villous near the petiole, trichomes simple, abaxial surface reddish, with microscopic glandular trichomes sparsely distributed, villous along the principal veins, trichomes simple, margins ciliate, apex acuminate, base cordate, lobes not overlapping the petiole, venation actinodromous, veins 7–8. Inflorescences in 5-branched cymes, 25–34 cm long, rachis vinaceous, 16–24 cm long, villous. Male flowers ca. 10 mm long, pedicels pink, 8–9 mm long, puberulous; tepals 4, external pair white, broadly ovate, 9–10 × 8–9 mm, with diminutive glandular trichomes sparsely distributed on dorsal surface, apex rounded, margins ciliate, with simple trichomes, pink, 1–1.5 mm long, internal pair white, elliptic, ca. 5 × 1.5 mm, glabrous, margins entire, stamens 12–23, free, ca. 3 mm long, anthers yellow, elliptic, ca. 2 mm long (including the connective), rimose, with lateral openings, filaments ca. 1 mm long. Female flowers ca. 27 mm long, pedicels reddish, ca. 15 mm long, puberulous, bracteole 1, ovate, ca. 5 × 3 mm long, with diminutive glandular trichomes sparsely distributed on dorsal surface, margins ciliate, tepals 5, white, oblong, 13–15 × 3–4 mm, with diminutive glandular trichomes sparsely distributed on the dorsal surface, margins ciliate, with simple trichomes, 1–1.5 mm long; ovary pink, ca. 9 × 11 mm (including the wings), with diminutive glandular trichomes sparsely distributed, placentae entire, 3–locular; stigmas 3, branches spiraled, yellow, ca. 2 mm long. Capsules 13–16 × 15–19 mm (including the wings), peduncles 24–27 mm long, puberulous; wings brown, subequal, the largest one truncate at apex; locular region ovate to elliptic, 4–5 mm long, brown, glabrous. Seeds oblong.

Etymology:—The specific epithet refers to the margins of the male and female tepals having long slender trichomes.

Phenology: —Flowering from February–July; fruiting November.

Distribution and ecology: — Begonia fimbritepala is a narrow endemic species from Rio de Janeiro State, in Miguel Pereira and Nova Iguaçu municipalities, not Queimados as described in the voucher Fraga 1735. Those places are about 15 km distant from each other. This species grows within montane forests, at elevations between 557 and 630 m asl. It is found in shady localities, with sun exposure facing south, on rocky slopes or on cambisol with a continuous process of pedological maturation. A soil sample was taken in November 2019 at 0–5 cm deep in the Parque Municipal da Rocha Negra, Miguel Pereira, Rio de Janeiro State, and analysis of soil texture and composition were obtained by the Laboratório de Gênese e Classificação do Solo (Instituto de Agronomia, UFRRJ) following Teixeira et al. (2017). The soil is a sandy loam soil of the following composition: Al, 0.65 cmol c dm-3; K, 0.78 cmol c dm-3; Na, 0.68 cmol c dm- 3 and P, 44.0 mg kg-1. It is known from two locations, both containing few individuals, with about one to three plants per square meter. Accordingly, B. fimbritepala is provisionally assessed as Vulnerable (VU D2) under IUCN Red List criteria ( IUCN Standards and Petitions Committee, 2019).

Additional specimens examined (paratypes):— BRAZIL. Rio de Janeiro: Miguel Pereira, Parque Municipal da Rocha Negra, antiga estrada de ferro de Miguel Pereira a Vassouras , 22° 29’ 03.6” S, 43° 31’ 08.7”, 20 November 2013, Jacques with Wängler et al. 1873 ( RBR!) ; ibidem, 557 m, 13 November 2019, Jacques with Wängler 2043 ( RBR!) ; Nova Iguaçu [Queimados], trilha para Rio dÓuro, 22° 37’ 67” S, 43° 30’ 62” [22° 38’ 07” S, 43° 31’ 02”], 420 m, 9 February 2007, Fraga with Bocayuva & Cardoso 1735 ( RB!) .

Taxonomic notes:— Begonia fimbritepala can be easily recognized by its combination of transversely ovate blades, glabrous on the adaxial leaf surface, apart from being villous with simple trichomes near the petiole, villous with simple trichomes along the principal veins on the abaxial leaf surface, and by having very long (1–1.5 mm) trichomes on the margins of tepals of the male and female flowers. This species resembles B. olsoniae by its rupicolous habit, transversely ovate leaf blades and size of male flowers. Begonia fimbritepala , however, has glabrous leaves on the adaxial surface, except by being villous nearest the petiole, villous abaxial veins, with simple trichomes (vs. hispid on both surface, squamulose abaxial veins, fimbriate scales), villous petioles (vs. squamulose), stipules glabrous along the entire length, except by being villous on the principal veins (vs. adaxially pilosous) and female tepals with ciliate margins (vs. entire to slightly crenulate).

Figures

FIGURE 1. A–J. Begonia fimbritepala E.L. Jacques. A, Habit, showing infructescence; B, Margins and apex of leaf; C, Stipules; D, Male flower; E, Details of margins of external male tepals; F, Female flower; G, Bracteole of the female flower; H, Stamen; I, Capsule; J, Capsule in cross section. Illustration by Maria Alice Rezende from M. S. Wängler 1383 (A–H) and E.L. Jacques et al. 1873 (I–J).

FIGURE 2. A–H. Begonia fimbritepala E.L. Jacques. A, Habitat; B, Details of habit showing inflorescence; C, Details of habit; D, Stem, adventitious roots, stipules and petioles; E, Details of indumentum of petiole; F, Male flowers; G, Female flower; H, Capsule (A, C–D, H from E.L. Jacques et al. 1873; B, F & G from M. S. Wängler 1383; E from E.L. Jacques et al. 2043). (A=6 cm; B=30 cm; C= 10 cm; D= 2.5 cm; E= 1.5 cm; F= 7 mm; G= 9 mm; H= 5.5 mm). A, C, D & H, Photos J. Wesenberg; B, F & G, Photos M.S. Wängler; E, Photos M.C. Souza)

FIGURE 3. Distribution of Begonia fimbritepala (circle).