Begonia tamoiana E. L. Jacques & P. W. Moonlight. A, Habitat 2024, sp. nov.
Creators: name: Jacques, Eliane De Lima
name: Moonlight, Peter W.
name: Junior, Alfredo Jose Dos Santos
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia tamoiana

description: Begonia tamoiana E.L.Jacques & P.W.Moonlight sp. nov. (Fig. 1, 2)
Begonia tamoiana is most similar to B. magdalenensis Brade (1945: 19) but differs in having abaxial leaf blades with simple trichomes throughout (vs. 2-branched trichomes throughout) and 2–3-branched trichomes on the principal veins (vs. squamulose on the principal veins), petioles with simple and 2–3-branched trichomes (vs. densely squamulose), and ovate wings capsule (vs. triangular).
Type: BRAZIL. Rio de Janeiro: Paraty Municipality, Perequê, Estação Ecológica dos Tamoios, trilha das Três Nascentes, 23º01’S, 44º33’W, 126 m, 25 April 2016, E.L. Jacques & A.J. Santos Junior 1957 (holotype RBR [RBR00038924], isotype RB).
Herbs, prostrate, to 20–50 cm tall (excluding the inflorescence). Cystoliths absent. Stems prostrate; internodes (1.5–) 2–4 cm long, succulent, greenish-brown, villous, with simple and 2-branched trichomes, hairs hyaline. Stipules persistent, subcarnose, greenish to pinkish to brown, and scarious when mature, 7–11 × 4–7 mm, broadly ovate, apex retuse to apiculate, margins entire to slightly undulate, sparsely puberulous to densely puberulous on the principal veins, trichomes simple. Leaves simple, petioles reddish, 11–12(–33) cm long, puberulous, with simple trichomes with flat bases, 2-branched trichomes, and glandular microscopic trichomes along the entire length, and a loose ring of 2–3-branched trichomes at the petiole insertion, leaf blades basifixed, lobate, transversely ovate, asymmetrical, fleshy, 12–17 × 8–11 cm, apex acuminate, base cordate, lobes not overlapping the petiole, margins ciliate, adaxial surface shiny green, light green on the veins, densely puberulous, with microscopic glandular and simple trichomes, hairs hyaline, abaxial surface greenish, villous, with microscopic glandular and simple trichomes throughout and 2–3-branched trichomes on the principal veins, hairs reddish, venation actinodromous, with 7 primary veins from the base. Inflorescences 2–3-branched cyme, bearing up to 3 flowers, 14–15 cm long (including the rachis), rachis 7.2–14 cm long (up to 17.5 cm when fruiting), puberulous, with simple and microscopic glandular trichomes, greenish. Bracts caducous, 3–5 × 0.5–1 mm, elliptic to lanceolate, apex acute to long acuminate, margins entire, greenish, membranaceous, with microscopic glandular trichomes. Staminate flower: pedicels 7–13 mm long, white, with sparsely distributed microscopic glandular trichomes, tepals 4, external pair white, ovate, 7–15 × 5–9 mm, apex acute, base acute, margins entire, membranaceous, puberulous, with simple and microscopic glandular trichomes, hairs reddish, internal pair white, 9–13 × 3–5 mm, elliptic, apex acute, margins entire, membranaceous, glabrous, stamens 17–19, free, filaments 0.5–1 mm long, connective slightly projecting, obtuse, anthers 1.5–3 mm long, oblong, rimose, extrorse, yellow. Pistillate flower: pedicels 7–11 mm long, white, with microscopic glandular trichomes densely distributed, bracteoles absent; tepals 5, white, unequal, the largest (9–10)12–13 × 5.5–7 mm, the smallest 7–11 × 3–6 mm, elliptic, apex acute, margins entire, membranaceous, with microscopic glandular trichomes on dorsal surface, ovary 3-locular, ca. 11 × 13–14 mm (including wings), locular region 2–2.5 × ca. 1.5 mm, ovoid, white, with sparsely microscopic glandular trichomes, 3-winged, wings unequal, flat, white, the largest wing 7–9 × 6–7 mm, the smallest wings 8–9 × 2–3 mm, white, with sparsely microscopic glandular trichomes, placentae entire, stigmas 3, 3–4 mm long, bifurcate, branches spiraled, yellow. Capsule 11–14 × 15–16 mm (including wings), transversely elliptic to depressed obovate, basally dehiscent, with microscopic glandular trichomes, brown, peduncles 11–13 mm long, with glandular microscopic trichomes, brown, wings 3, unequal, flat, the largest wing 8–15 × 6–10 mm, ovate, smallest wings 8–11 × 2–4 mm, ovate, with microscopic glandular trichomes, locular region (8–)10–11(–14) × 5–6 mm, ovate, brown, with microscopic glandular trichomes, seeds oblong.
Etymology:—The specific epithet refers to the Tamoios, indigenous peoples who inhabited the Brazilian coast in the 16 th century, the type locality for the new species.
Phenology: —Flowering and fruiting March to July.
Distribution and ecology: — Begonia tamoiana is only known in the area close to the administrative headquarters of the Tamoios Ecological Station (ESEC Tamoios), approximately 1 kilometer away from the boundaries of the Serra da Bocaina National Park (Parque Nacional da Serra da Bocaina) in an area that corresponds to the “buffer zone” that connect these conservation areas. It has been collected at an elevation of 63 –126 m in the Atlantic Rainforest and grows primarily on the top and side of large boulders surrounding small watercourses.
Provisional conservation assessment:— Begonia tamoiana is known from a single locality within the protected land surrounding the administrative headquarters of the Tamoios Ecological Station. As such, no known threats to the species are known. Regardless, the species’ small range means it is susceptible to stochastic events and as such we assess this species as Vulnerable (VU D2) under IUCN criteria (IUCN 2022).
Additional specimen examined: — BRAZIL. Rio de Janeiro: Paraty, Perequê, Estação Ecológica de Tamoios, trilha das Três Nascentes, 23º01’S, 44º33’W, 76 m, 22 June 2023, E.L. Jacques & P.W.Moonlight 2091 [RBR00058596]; ibidem, 23°33’ S, 46°43’ W, 63 m, 21 March 2018, M. Colli-Silva, G.G.N. Alves & D.G. Almeida 82 [SPF242481].
Taxonomic notes:— Begonia tamoiana is highly distinctive among species in its range and can be easily recognized by its lobate, transversely ovate leaf blades, its ovate outer pair of staminate tepals with acute apex, and its transversely elliptic to depressed obovate capsules with ovate wings. Begonia tamoiana is morphologically similar to B. magdalenensis Brade (1945: 19) in the shape of its leaf blades and habit. The new species differs from B. magdalenensis by longer petioles (11–12(–33) cm vs. 6–8 cm), puberulous, with simple and 2–3-branched trichomes (vs. densely squamulose, fimbriate scales), with a ring of trichomes at apex (vs. absent); abaxial leaf blades with simple trichomes throughout (vs. 2-branched trichomes throughout) and 2–3-branched trichomes on the principal veins (vs. squamulose on the principal veins); cymes bearing up to 3 flowers, 2–3-branched (vs. with ca. 16 flowers, 4- branched,) and its ovate winged capsule, descending at apex and widest at middle (vs. triangular, truncate to ascending at apex and widest at the apex). For the Begonia species of the Atlantic Rainforest, leaf morphological variations and geographical distribution are considered important tools for distinguishing species, especially since there are no genetic and reproductive data available for most Begonia species. Often, just by analyzing the shape of the leaves, the indumentum and the type of the trichomes, it is possible to recognize Brazilian species that are morphologically close. Jacques (2018) re-established at the rank of species Begonia oxyphylla de Candolle (1859: 140), distinguished from Begonia arborescens Raddi (1820: 408) by the indumentum. Begonia altimontana Jacques (2022: 139) was established as a distinct species from B. ramentacea Paxton (1846: 73), mainly due to the leaf indumentum. Begonia magdalenensis is endemic to the north of the Serra do Mar Mountain range in the north of Rio de Janeiro State. It grows at an elevation of around 1.000 meters in a region around 300 kilometers, in a straight line, away from B. tamoiana. Begonia tamoiana is provisionally included the B. sect Pritzelia (Klotzsch) A.DC. (1859), which includes all the rhizomatous species in Southeast Brazil, and we await a more in-depth study of this species and the others that make up this section.
description: Published as part of Jacques, Eliane De Lima, Moonlight, Peter W. & Junior, Alfredo Jose Dos Santos, 2024, Begonia tamoiana (Begoniaceae), a new species from Atlantic Forest of Rio de Janeiro State, Brazil, pp. 159-164 in Phytotaxa 669 (2) on pages 160-163, DOI: 10.11646/phytotaxa.669.2.8, http://zenodo.org/record/14519047