Begonia schizostyla M.D.Miranda, 2023

Miranda, Marcelo Dias, 2023, A new insular species of Begonia (Begoniaceae) from São Paulo State, Brazil, Phytotaxa 630 (2), pp. 142-148 : 143-147

Begonia schizostyla M.D.Miranda , sp. nov. § Astrothrix ( Figs. 1–3 )

Begonia schizostyla is similar to Begonia bullatifolia L. Kollmann (2009:118) in having a bullate adaxial leaf surface, thyrsoid inflorescences similar in size, obovate anthers and bilaminate placenta. However, B. schizostyla differs in its petiole (sulcate with 5 ridges vs. cylindrical); petiole vestition (appressed stellate trichomes vs. erect stellate trichomes); larger leaves (21.2–22.4 × 20– 18.5 cm vs. 7.5–10 × 9–13 cm); leaf base (reniform, basal lobe wide open vs. cordate, almost overlapping the petiole); leaf margin (sinuate-dentate vs. entire); inflorescence peduncle color (light green vs. red-brown); tepal color (white vs. pinkish-white); staminate flower outer tepal shape (triangular, apex triangulate vs. ovate, apex obtuse) and inner tepal size and shape (1–1.5 × 0.4–0.8 cm, obovate, base acute, apex rounded vs. 1.2–1.5 × 0.6–0.9 cm, obovate to espatulate, base cuneate, apex obtuse); tepal and ovary vestition (villous glandular trichomes vs. tomentose glandular trichomes).

Type:— BRASIL. São Paulo: Município de Ilhabela, Baía dos Castelhanos . Vivendo sobre pedras redondas que se projetam no chão da selva. Pecíolo de cor coral, folhas verde-escuras na face adaxial, verde-esbranquiçada na face abaxial. Flores brancas, tricomas hialinos. Frutos verde-claro. 23°51’10.49”S, 45°17’16.35”W, elev. 90 m, M.D. Miranda & M.R. Miranda 504, 09 December 2022, (holotype RB [ RB852826 ] , isotypes RBR [ RBR00056018 ], SPF [ SPF258083 ]).

Description: —Rupicolous, rhizomatous herb, (23–) 34–40 cm tall (excluding the inflorescence), prostrate, leaves erect to pending, pubescent with appressed stellate trichomes and long glandular trichomes at the inflorescence. Stem rhizomatous, 12–13 cm long, 0.9–1.9 cm diam., reddish or reddish-green, with lenticels, internodes ca. 0.5 cm long, with copper stellate trichomes, and sparse white multicellular fleshy hairs. Stipules persistent, 3.8–5.4 × 2.5–2.9 cm, oblanceolate, very smooth and papyraceus when dry, slightly translucent, pinkish-orange, concave, sulcate between principal nerves in upper portion, apex inflexed caudate, margin entire, pubescent on dorsal surface with coppery to coralline stellate trichomes. Leaves simple, petioles 22–25 cm long, green, covered with copper to coral pink trichomes, and sparse white multicellular fleshy hairs, sulcate with 5 ridges, leaf blades basifixed, (18.5–)21.2–22.4 × (17.5–) 18.5–20 cm, orbicular, slightly asymmetric, apex acute or apiculate, base reniform, basal lobes wide open, forming a right angle, margin dentate, adaxial surface dark green, bullate, shiny, glabrescent, abaxial surface whitishgreen, with appressed copper stellate trichomes throughout, margin sinuate-dentate, venation palmate, veins 11–13(– 14), nerves prominent on abaxial surface and petiole insertion, some joined at the base by a membrane. Inflorescence thyrsoid, sometimes subtended with one minuscule leaf, petiole (0.5–) 0.7–1.6 cm, lamina (0.9–)1.3–1.5 × (1–) 2 cm; peduncle terete when fresh, sulcate in herbarium material, 19.5–30 cm long, with (3–)5–6(–9) nodes, fresh peduncles and rachis light green, with reddish spots, first internode 13–19 cm, second (2.5–) 5–5.7 cm, third 1.5–1.8 cm, with hyaline glandular trichomes, and white stellate trichomes throughout. Bracts: two large bracts subtend the first node, (0.9−)2.5−2.3 × (0.5−)1.4− 1.2 cm, greenish-white, slightly light pink at the base, hyaline, carinate midrib in the upper portion, lanceolate to oblanceolate, deciduous, one rarely persisting, twisted caudate to acute apex, margins revolute at the base, minutely sinuate-dentate, ciliate with glandular trichomes, dorsal surface villous with hyaline glandular trichomes, and inconspicuous white stellate trichomes; higher bracts 7–9(–13) × 4–7 mm, greenish-white, persistent, triangular, apex acute, margins revolute at the base, minutevely sinuate-dentate, ciliate with glandular trichomes, dorsal surface villous with hyaline glandular trichomes, and inconspicuous white stellate trichomes. Staminate flower pedicels (1.3–)1.7–2.5(–3.2) cm long, with glandular trichomes, hairs less than 1 mm long, hyaline, tepals 4, external pair white, dorsally light green at the base, triangular, apex acute, 18–28 × 10–19 mm long, margins ciliate, dorsal surface covered with 1 mm glandular trichomes, internal pair white, obovate, base acute, apex rounded and concave, 10–15 × 4–8 mm, glabrous, stamens 28–36(–42), 3–4 mm long, filaments 1–2(–3) mm long, fused at the base into a column, anthers 1 mm long (including the connective), obovate, extrose, cadmium yellow. Pistillate flower pedicels white to slightly green, 1.3 cm long, glandular trichomes; bracteoles absent; tepals 6, white, unequal, 3 largest ones 1.3–1.5 × 0.8–1.2 cm, white, ovate to broadly triangulate, apex subobtuse, margin ciliate, hairs less then 1 mm, dorsal surface covered with glandular trichomes, hairs 1 mm, 3 smallest ones 0.7–0.9 × 0.3–0.6 cm, white, obovate, apex rounded, glabrous; ovary greenish-white, 3-locular, glandular trichomes throughout, wing margins minutely serrulate and ciliate on the margin, placenta bilaminate, stigmas 3, ca. 2–4 mm long, quadfurcated, 12 branches joined at the base, twisted, with stigmatic papilla at the apex of the stigma, at least one of the 4 branches is flabellate, and one of the twelve branches is bifurcate at the apex, early deciduous, sometimes retaining a single branch, ca. 4 mm long, cadmium yellow. Fruits: pedicel 1.9–2.1 cm long, villous, long glandular trichomes, light green; capsule (1.6–)1.9– 2.1 × 2.3–2.5 cm (including the wings), transversely obovate to ovate, dehiscent on basal portion, with glandular trichomes, light green when fresh, light brown when mature, wings 3, unequal, the largest one 1.6–2 × ca. 1.7 cm, apex triangular or broadly triangulate with a strongly rounded base, slightly descendant, smallest ones 1.4–1.6 × 0.4 cm, apex rounded, base rounded, fruit wings becoming decayed after spreading the seeds, wings margin ciliate and minutely serrulate toward the apex, locular region 10–13 × 7–8 mm, villous with glandular trichomes, light green, elliptic. Seeds oblong.

Etymology:—The specific epithet refers to the styles of the species, being multifid, presenting many branches. Phenology:—Flowering and fruiting from December to February. Distribution and ecology:— Begonia schizostyla is endemic to São Sebastião Island, in the municipality of Ilhabela, São Paulo, Brazil. The new species lives within the limits of the Ilhabela State Park, and was found in two areas to the south of the island, namely Enseada das Enchovas and Baía dos Castelhanos, it grows in Ombrophilous Dense Submontane Forest at an elevation between 165–250 msl, on rocks inside the primary forest. The species has been observed on rocky outcrops along the slope in the surrounding area of Cachoeira do Gato. It also grows over walls of large round rocks protruding from the soil of the interior of the rainforest. At Bonete Beach Trail, the habitat where B. schizostyla was found, it is located on humid slopes, whose water courses are intermittent and receive water seasonally in times of higher rainfalls.

Additional specimens examined:— BRASIL. São Paulo: Município de Ilhabela, Trilha que leva à Praia do Bonete. Vivendo sobre pedras no interior da floresta. 23°54’46.97”S 45°20’33.55”W, elev. 150 msl., 03 December 2020, M.D. Miranda & E.G.V. Rodrigues 15 (RBR [RBR00056022]).

Taxonomy:— Begonia schizostyla belongs to Begonia sect. Astrothrix Moonlight (2018: 286) due to its perennial, acaulescent, rhizomatous habit, an indumentum of stellate hairs, axillary thyrsoid inflorescences, pistillate flowers with 6 free perianth segments, 3-locular ovaries with 3 unequal wings and bilaminate placentas.

Relationships:— B. schizostyla M.D.Miranda resembles B. crispula Brade (1950: 134) and B. bullatifolia due its rounded-reniform bullate leaf blades, palmate veins and by the presence of stellate trichomes. The new species can be distinguished from B. crispula by its inflorescence (thyrsoid vs. cymose); external tepals of staminate flower (ovate-triangular vs. suborbicular); anthers (oval vs. oblong); placenta (bilaminate vs. entire); tepals of pistillate flower (3 outer, ovate to broadly triangulate, 3 inner, obovate vs. 2 outer, ovate, 3 inner, obovate to oblanceolate); stigmas (multibranched vs. bifurcated), and tepal vestition (villous glandular trichome vs. granular).

The new species also differs from B. bullatifolia in its stem size and colour (0.9–1.9 cm diam., reddish or reddish-green vs. 0.8–1.2 cm diam., greenish-brown); stipule size (3.8–5.4 × 2.5–2.9 cm vs. 1.3–2 × 0.8–1.2 cm); petiole length (22–25 cm vs. 5.5–12.5 cm); leaf apex (acute vs. rounded); bracts (greenish-white, triangular vs. green, obovate to orbiculate); bract apex (acute vs. retuse and lightly mucronate); pistillate flower pedicels (white to slightly green, 1.3 cm long vs. pinkish, 1.5–2.2 cm long); 3 external tepals in the pistillate flowers (white, 1.3–1.5 × 0.8–1.2 cm, broadly triangulate, apex subobtuse vs. pinkish-white, 1.3–2.2 × 0.6–1.2 cm, ovate to obovate, apex obtuse), and 3 internal tepals (0.7–0.9 × 0.3–0.6 cm, obovate, apex rounded vs. 0.9–1.6 × 0.6–0.8 cm, obovate, apex obtuse). In addition to the individual characters, B. schizostyla is also distinguishable by its greater size, as B. bullatifolia is markedly smaller and more delicate in stature.

Figures

FIGURE 1. A–O. Begonia schizostyla M.D.Miranda. A, Habit; B, Adaxial leaf surface; C, Petiole insertion in abaxial leaf surface; D, Stipule; E, Staminate flower bud; F–G, Primary floral bracts; H, Staminate flower, anterior view; I, Column of stamens; J, Stamen, lateral view; K, Pistillate flower; L, Pistillate flower after pollination; M, Stigma detail; N, Immature fruit; O, Ovary cross section. (Illustration by M.A. Rezende based on M.D.Miranda 504).

FIGURE 2. A–H. Begonia schizostyla M.D.Miranda. A, Plants in situ; B, Vigorous individual growing in the upper part of a boulder, with staminate flowers at anthesis above, and pistillate flower about to open below; C, Petiole base and stipule with peduncle basal portion; D, First node of the inflorescence, face view, showing minuscule leaf and dried primary bracts; E, First node of the inflorescence, posterior view, showing fresh primary bract; F, Pistillate flower after pollination; G, Insertion of the petiole on leaf base, abaxial surface; H, Insertion of the petiole at leaf base, adaxial surface. (Scale Bars: C= 5.2 cm; D= 2 cm; E= 1.4 cm; F= 1.5 cm). (B, F from M.D.Miranda 16; all others from M.D.Miranda 504).

FIGURE 3. Distribution map of Begonia schizostyla M.D.Miranda (white dots) in the Ilhabela municipality.