Begonia iarae M.D.Miranda, sp. nov. § Pritzelia (Figs. 1–3)

Type: — BRASIL. São Paulo: Ilhabela, trilha para o Pico do Baepi, 23°47’34”S, 45°19’55”W, elev. 770 m, 20 April 2024, M.D. Miranda & I. Miranda 631 (holotype RBR [RBR 61560]!, isotypes RB [RB 880348]!, SPF [SPF 266000]!).

Begonia iarae is most similar to Begonia fernando-costae Irmscher (1953: 52), by having similar indumentum of the stem, petiole, leaf surfaces and inflorescence peduncle, staminate outer tepals shape, pistillate flowers with five unequal perianth segments, but differs by having smaller and narrower leaves, 14.4–20 × 8.3–13 cm (vs. 24–26.3 × 15.5–17.5 cm), greenish-white abaxial leaf surface (vs. vinaceous), conspicuously dentate leaf margin (vs. entire to minutely dentate), narrowly acuminate leaf apex (vs. apiculate to cuspidate), few-flowered inflorescences, bearing 13–17 flowers (vs. multiflorous, bearing 24–50 flowers), inflorescence length, 18–21 cm (vs. 47 cm), first rachis length 0.9–1.3 cm long (vs. 2–6 cm long), pilose pedicels and bracts (vs. all glabrous), number of stamens 15–17 (vs. (14–)20–35), 1 filiform bracteole (vs. 2 linear-lanceolate or linear), pistillate flower always white (vs. pinkishwhite), obtuse capsule largest wing apex (vs. acute and narrowly triangular).

Description: —Herbs, rhizomatous, fleshy, erect to decumbent, rupicolous, ca. 25 cm tall excluding the inflorescence, villous, with simple trichomes, 2-branched trichomes and 3–6-branched fimbriate scales and hyaline trichomes. Stem erect to decumbent at the base, up to 53 cm long including decumbent part, with reddish-pink internodes, greenish at the apex, white dots throughout, 1–4(–6) cm long, 0.5–0.8(–1) cm diam., squamulose with fimbriate scales and simple trichomes, scales 3–5.5 mm long, simple trichomes 1.2–4.5 mm long. Stipules 1.9–2.2(–2.5) × 1.9–2.3 cm, light green, persistent, scarious, base flat to cucullate from the base to the center, deltoid to triangular, with a crest of 2–3-branched fimbriate scales on the veins, villous with simple trichomes in the center and margin, trichomes 1.5–2.2 mm, margins dorsally ciliate and distinctly flat, apex acute, folded, aristate with a 2–3 fimbriate scale, arista 2–2.5 mm long, 0.2 mm wide, carinate and prominent principal vein in the apex, 13–15 veins. Leaves simple, petioles abaxially cylindrical, flat to slightly sulcate adaxially, reddish-pink, (7–) 8.5–12.7 cm long, 4–7 mm wide at the base, 0.3 cm wide at the apex, villous, with simple trichomes and 3–6-branched fimbriate scales, 5.5–7.3 × 0.9–1.5 mm; leaf blades basifixed, transversely oblong, asymmetrical, villous and squamulose, 14.4–20 × 8.3–13 cm, adaxial surface dark-green, whitish green near the petiole insertion and lighter green lower third of the veins, veins slightly prominent, grooved in relation to the limbus, with simple trichomes and 2–3(–4)-branched fimbriate scales, hyaline, sickle-shaped, petiole insertion trichomes 4.5(–7) mm long, vein trichomes 2–4 mm long, blade trichomes 1–2.2 mm long, abaxial surface whitish green, trichomes similar to the adaxial surface, veins prominent, margin slightly undulate to flat, conspicuously dentate, teeth 3–8 mm long, apex acuminate-caudate, base cordate, lobes not overlapping the petiole on mature leaves, venation actinodromous, veins ca. 10, dichotomous. Inflorescence 4–5-branched cyme, 13–17-flowered, 18–21 cm long including rachis (up to 23 cm long when fruiting), peduncles 13.5–18.8 cm long, villous, with simple trichomes, (1–) 3.5 mm long, and sparse 2–3-branched fimbriate scales with a small base, 2 × 0.3–0.5 mm, rachis reddish-green, first rachis 0.9–1.3 cm long (ca. 2.5 cm long when fruiting), second rachis 4–6 mm long; bracts caducous, greenish-white, first bract ca. 1 cm long, other bracts, (3.6–)8.3 × (0.3–) 1.5 mm, dorsally pilose, apex aristate or not, greenish. Staminate flowers: pedicels reddish-white, redder at the base, white distally, 14–16 mm long, except in the central flower of the cyme when it is ca. 26 mm long, villous with reddish to hyaline simple trichomes, hairs 0.5–1.5 mm long; tepals 4, external pair white, unequal, with slightly hyaline base, ovate, 16–17(–20) × 8–10 mm, base rounded, apex acuminate-caudate, margins entire to dorsally ciliate, base coriaceous, apex membranaceous, sparsely villous with simple reddish to hyaline trichomes, 0.4–1.5(–2) mm long, internal pair white, unequal, oblanceolate, 9–14 × 4–6 mm, one of the pair 0.2–1.5 mm longer than the other, stamens (15–)16–17, free, 3(–4.8) mm long, filaments 0.5–0.8(–1.3) mm long, anthers 2.1–3 mm long, light yellow, connective 2.5–3.5 mm long, yellow, narrow elliptic, rimose with lateral openings, extrorse. Pistillate flowers (only immature observed) pedicels reddish-white to greenish-white, ca. 8 mm long, with sparsely distributed simple trichomes, trichomes hyaline, 0.8 mm long, bracteole 1, caducous, located slightly below the ovary base, filiform, apex aristate, similar to a trichome, 3–3.5 × 0.3(–0.5) mm, translucent-green, tepals 5, white, unequal, 4 largest tepals ca. 12 × ca. 6 mm, symmetric to slightly asymmetric, ovate, base rounded, apex acute, margin entire, membranous, with sparse simple trichomes on dorsal surface in the center and margin, trichomes hyaline, 0.5–1 mm long, the smallest tepal 11 × 4 mm, lanceolate, base acute, apex accuminate, margin entire, membranaceous, with sparse simple trichomes on dorsal surface in the center and margin, hairs hyaline, 0.6–1 mm long; ovary 3-locular, 6.8 × 5.5 mm (including the wings), with 1–4 hyaline trichomes at the wing margins, white, placentae entire, stigmas 3, ca. 1.7 mm long, bifurcate, branches spiraled, with stigmatic papillae distributed along the branches, yellow. Capsules 1.8 × 1.4 cm (including the wings), transversely depressed-obovate, dehiscent on basal portion, glabrous, except by the pilose peduncle and wing margins, reddish when fresh, dark brown when mature, peduncles 12 × 0.8–1.5 mm, flattened, sparsely pilose with simple trichomes, reddish, wings 3, unequal, the largest one 15 × 8.4 mm, apex obtuse, the smallest one 13 × 3.5 mm, apex rounded, locular region 11 × 6 mm, elliptic, wing margins with 1–4 trichomes, seeds oblong.

Etymology: —The specific epithet is a tribute to my sister Iara Miranda. The name Iara, also spelled Uiara, Yara or Hiara, alludes to a figure in Brazilian folklore based on Tupi and Guaraní mythology, derived from the Tupi word yîara meaning ‘water lady’ or ‘mother of the waters’, and refers to a water spirit, nymph or mermaid that lives in the Amazon River. The legend says that Iara would lure the men with her melodic voice and physical beauty, taking them to her home at the bottom of the river, to be drowned. While rooted in mythology, the name Iara has become a popular given name in Brazil, embodying qualities of beauty, mystery, and the allure of water.

Phenology: —Flowering and fruiting in April–May.

Distribution and ecology: — Begonia iarae is currently known only from the type locality, Pico do Baepi in Ilhabela municipality, located in the north coast of São Paulo, Brazil. This species inhabits montane forests, close to tropical bamboo forest, in shady and humid inclined rocky outcrops partially covered by mosses, growing in the understory of a well preserved forest, over decomposed and semi decomposed leaf litter, which accumulates over the rocks. The type collection site is at an elevation around 770 m. The new species shares the same habitat with Begonia herbacea Vellozo (1831: pl.53) and B. integerrima. A population of thirteen mature individuals was observed, among these only six were fertile at the collection date, bearing staminate flowers at anthesis, and pistillate flowers in development. Only one individual that was with a single fruit was observed and collected.

It is an insular endemic species that is only known from its type locality with an area of occupancy of <10 km ². Despite being within the limits of the conservation area Ilhabela State Park, the species is still subjected to some threats, considering that soil erosion may occur and decrease the quality of the species habitat that is directly below a trail. Moreover, illegal collection may also be a concern, considering the high ornamental value attached to Begonia species. The exact distribution range of the species on the island is not yet fully known, but an estimate of occurrence of the species was made using the polygon tool in GoogleEarth, considering the possible range in areas between 500–800 m, in the northern side of the island. The calculated extent of occurrence of the species was around 34 km ², this extent of occurrence matches with the values indicated in the criteria here applied. Accordingly, B. iarae is provisionally assessed as Critically Endangered (CR B1 & B2ab(i,iii,iv) & C2a(i)) under IUCN Red List criteria (IUCN Standards and Petitions Committee, 2022).

Taxonomic notes: — Begonia iarae can be recognized by having reddish-pink stems and petioles, which are squamulose and villous, dentate leaf blades, light green adaxial leaf surface, pubescent on both surfaces with fimbriate scales and simple trichomes, few-flowered inflorescences, with pilose staminate and pistillate flower pedicels, pistillate flowers with one deciduous filiform bracteole, with five perianth segments and capsule largest wing with obtuse apex, pilose on wings margin.

In addition to the diagnostic characters listed above, when compared with B. fernando-costae, B. iarae also differs in its lighter green adaxial leaf surface color, being darker green in B. fernando-costae, in addition the veins of B. iarae end in long teeth, exceeding the margin by 3–8 mm, the margin being conspicuously dentate, different from B. fernando-costae, where the vein apex exceeds 1–1.5 mm, the margin being minutely dentate according to the prologue of the species. After examining the syntypes of B. fernando-costae, it is clear that Irmscher’s species has many more pistillate and staminate flowers, and the peduncle of the inflorescence is much thicker when compared to that of B. iarae. Begonia fernando-costae, in situ, is much more robust in terms of the thickness of it’s stem and petioles, with more succulent and bigger leaves, when compared to the new species that appears much more delicate.

Begonia iarae also resembles B. lorenzii E.L. Jacques (2020: 39) by having hispid simple trichomes, greenish stipules, dentate leaf margins, with acuminate apex, pilose on both surfaces. It differs by the kind of trichomes on the stem, petiole and both leaf surfaces (simple trichomes and fimbriate scales vs. only with simple trichomes), stipule shape (deltoid to triangular, cucullate in the center vs. triangular, carenate), inflorescence length (18–21 cm long vs. 7 cm long), staminate flower external tepal apex (acuminate-caudate vs. obtuse to rounded), and number of pistillate flowers tepals (5 vs. 3).