Begonia umbrosa M. D. Miranda & E. L. Jacques. A, Abaxial 2022, sp. nov.
Creators: name: Miranda, Marcelo Dias
name: Jacques, Eliane De Lima
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia umbrosa

description: Begonia umbrosa M.D.Miranda & E.L.Jacques, sp. nov. (Figs. 5, 6, 7)
Diagnosis. Begonia umbrosa is closely similar to Begonia cornitepala Irmsch (1953: 41). It differs chiefly in having peltate leaf blades (vs. basifixed) and pauciflorus cymes (vs. multiflorus).
Type: — BRAZIL. São Paulo State: Município São Sebastião, Porto Grande, trilha do gasoduto que leva ao Platô do Guaecá, erva delicada vivendo sobre rochas no interior da floresta, caule decumbente, folhas verdes, flores brancas, frutos rosados. Elevation 500 m, 30 October 2020, M.D. Miranda 14 & E. G. V. Rodrigues (holotype: RBR!).
Diminutive rupiculous herbs, up to 25 cm tall, glabrous on the vegetative parts. Stem prostate, pendulous, rhizomatous, cylindrical, internodes 1–2.5 cm long, 1–2 mm diam, lenticellate, greenish or reddish, glabrous. Stipules persistent, revolute, foliaceous, 4–5 × 2 mm, ovate-lanceolate, apex acute, aristate, arista 1–2 mm long, margins entire, glabrous, green, reddish at the apex. Leaves asymmetric, petioles 1.2–2 cm long, 1 mm diam., cylindrical, greenish, or reddish, glabrous, leaf blades peltate, 6–5.5 × 2.5 cm, transversely obovate, asymmetrical, membranaceous, apex acuminate, revolute, base rounded, margins dentate, adaxial surface glabrous, flattened, dark green, abaxial surface glabrous, greenish-white, or reddish, venation actinodromous, primary veins 7–8, impressed on both surfaces. Inflorescence a monochasial cyme, 2-flowered, ca. 4 cm long, peduncle 1.5–2 mm long, glabrous. Bracts ca. 2.5 × 0.3 mm, linear, apex acute, margins entire. Staminate flower pedicels white, ca. 10 mm long, glabrous, tepals 4, external pair white, 11–15 × 9–13 mm, broadly ovate, apex acute and slightly retuse, margins entire, membranaceous, with microscopic glandular trichomes and a lump-like mass on outer surface, internal pair white, 10–11 × 4–5 mm, obovate, apex acute, base acute, margins entire, glabrous, stamens 13–16, ca. 2.5 mm long, filaments 0.7–1 mm long, free, anthers ca. 1.5 mm long (including connective), oblong, rimose, extrorse, yellow. Pistillate flower pedicels pinkish, 10–12 mm long, glabrous, bracteoles 2, similar to the bracts, ca. 2.5 × 0.3 mm, spaced from the base of the ovary, linear, apex acute, margins entire, tepals 5(–6), white, unequal, external-3, 9–11 × 5–6 mm, broadly ovate, apex acute, margin entire, glabrous, internal-2–3, 6–9 × 3.5–4 mm, elliptic, apex acute, margin entire, glabrous, ovary pinkish-white, 3-locular, 5–6 × 6 mm, with glandular trichomes, placentae entire, stigmas 3, ca. 2 mm long, bifurcated, branches spiraled, with stigmatic papillae distributed along the branches, yellow. Capsule 10–13 × 14–17 mm (including the wings), depressed ovate, dehiscent on basal portion, with microscopic glandular trichomes to glabrous, greenish-pink when fresh, light brown when mature, peduncles 10–15 mm long, glabrous, wings 3, unequal, the largest one 6–7 × 10–12 mm, apex truncate, the smallest one 4–5 × 10–12 mm, apex rounded, locular region 8 × 4 mm, elliptic, seeds oblong.
Etymology:—The epithet is from the Latin umbrosus (shady) in reference to the habitat of the new species, which was encountered growing on rocks in the shade of the tree canopy.
Phenology:—Flowering and fruiting in October.
Distribution and ecology:— Begonia umbrosa is known only from the type locality in the municipality of São Sebastião, on the slopes of Serra do Mar, São Paulo state. The species grows in Montane Ombrophilous Forest, at an elevation of 500 m, and is found growing over igneous rocky outcrops under the shade of the forest.
Provisional IUCN assessment: —We provisionally categorize this species as Critically Endangered (CR) under criteria B2ab (ii, iii), because it is known only from one locality and is suffering continuing decline in quality of habitat (IUCN Standards and Petitions Committee, 2019). Although the population of B. umbrosa occurs in the Serra do Mar State Park protected area, this species is still threatened due to the maintenance of the nearby Petrobras’ oil pipeline, and is located next to the under-construction Tamoios highway.
Additional specimen examined (paratype):— BRAZIL. São Paulo State: Município São Sebastião, Porto Grande, trilha do gasoduto que leva ao Platô do Guaecá, erva rupícola, glabrescente, vivendo em trecho de Floresta Ombrófila Densa Montana, trecho com presença de muitos afloramentos rochosos, caule decumbente. Elevation 500 m, 04 July 2021, M.D. Miranda 54 & E.G.V. Rodrigues (RBR!).
Taxonomic notes: —By having erect stems distally which are slightly flexuous at the base and a small appendage on the outer surface of the external staminate tepals, Begonia umbrosa resembles B. cornitepala Irmsch. (1953: 41). Begonia umbrosa is easily distinguished from B. cornitepala as it has peltate leaf blades (vs. basifixed); pauciflorus inflorescences, (2-flowered monochasial cyme vs. pluriflorous, dichasial, 3–4-branched cyme); external staminate tepals with lump-like mass on the outer surface (vs. with two horns in the center); pistillate flowers with 5(–6) tepals (vs. 5); a thinner stem (1–2 mm diam. vs. 2.5 mm); smaller leaves, 6–5.5 × 2.5 cm (vs. 5.5–9 × 3.5–6 cm); and shorter petioles (1.2–2 cm long vs. 2–5 cm; Fig. 8). It also resembles B. jureiensis S.J. Gomes da Silva & Mamede (2000: 24) in its presence of peltate leaf blades, and both these species are endemic to São Paulo State. Begonia umbrosa can be easily distinguished from B. jureiensis by the size and shape of leaf blades (6–5.5 × 2.5 cm and transversely obovate vs. 18–24.5 × 10–14.8 cm and ovate); the duration of its stipules (persistent vs. caducous); its bifurcate styles with spiraled branches (vs. flattened style branches, kidney-shaped); and its placentae (entire vs. bifurcated).
description: Published as part of Miranda, Marcelo Dias & Jacques, Eliane De Lima, 2022, Two new diminutive species of Begonia (Begoniaceae) from the north coast of São Paulo State, Brazil, pp. 147-158 in Phytotaxa 550 (2) on page 152, DOI: 10.11646/phytotaxa.550.2.4, http://zenodo.org/record/6641111