Begonia altimontana E.L.Jacques, 2022

Jacques, Eliane De Lima, 2022, Three Brazilian species of Begonia (Begoniaceae) from the state of Rio de Janeiro, Brazil, Phytotaxa 561 (2), pp. 138-150 : 139

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

Begonia altimontana is most similar to B. ramentacea Paxton but differs in its smaller leaf blades (5–7.5) 9–11 × (3–4) 6–7 cm (vs. 13–20 × 9–15 cm); its shorter petioles 7–10 cm long (vs. 12–25 cm), which are covered with flattened, fimbriate scales along their entire length (vs. curved inwards, shell-shaped); and in its bilamellate placentae (vs. entire).

Type:— BRAZIL. Rio de Janeiro: Teresópolis, trilha da travessia Petrópolis-Teresópolis , 1373m elevation, 29 April 2019, T. C. Alves 31 (holotype RBR 56196!, isotype RB!) .

Herbs, delicate, repent, ca. 10 cm tall (including the inflorescence). Cystoliths absent. Stem reptant, internodes 1–2 cm long, reddish to brown, squamulose to glabrescent. Stipules persistent, 5–6(–8) × 2–3(–7) mm, ovate to triangular, apex acute, margins ciliate, pilose on dorsal surface, scarious. Leaves simple, petioles 7–10 cm long, reddish, with flattened fimbriate scales along the entire length, scales 0.5–2 mm long, leaf blades basifixed, (5–)7.5–11 × (3–) 6–7 cm, entire, transversely ovate, asymmetrical, carnosus, base cordate, basal lobes rounded, not overlapping the petiole, margins ciliate, apex acuminate, adaxial surface glabrous, dark green, slightly light green on the veins, abaxial surface with simple and 2-branched trichomes along the entire surface and flat fimbriate scales on principal veins, scales fimbriate, ca. 0.5 mm long, vinaceous, veins 8–10, venation actinodromous. Inflorescence in 3-branched cymes, bearing ca. 10 flowers, 8.5–9 cm long (including the rachis), up to 11 cm long when fruiting, rachis ca. 5 cm long (up to 9 cm long when fruiting), puberulous, with simple trichomes, greenish. Bracts caducous, not seen. Staminate flower: pedicels ca. 14 mm long, greenish, glabrous, tepals 4, external pair 10–11 × 9–10 mm, broadly elliptic, apex rounded, margins entire, white, pinkish in the margins, glabrous, internal pair 6–8.5 × 2–4.2 mm, elliptic to obovate, apex obtuse, margins entire, white, membranaceous, glabrous, stamens ca. 12, ca. 3 mm long, filaments ca. 0.5 mm long, free, connective not projecting, anthers ca. 2 mm long (including connective), oblong, extrorse, yellow. Pistillate flower: pedicels 9–10 mm long, greenish to pinkish, with microscopic glandular trichomes, bracteoles absent, tepals 4, white, equal, 7–9 × 6–10 mm, broadly ovate, apex rounded, margins entire, membranaceous, with sparse microscopic glandular trichomes, ovary 3-locular, 5–6 × ca. 10 mm, white, with sparse microscopic glandular trichomes, wings unequal, largest one ca. 5 mm wide, two smallest ca. 2 mm wide, flat, white, placentae bilamellate, stigmas 3, ca. 4 mm long, bifurcate, branches spiraled, yellow. Capsule 7–8 × 14–15 mm (including wings), basally dehiscent, glabrous, light brown when mature, narrowly transversely elliptic, peduncles 10–14 mm long, glabrous, brown, wings 3, unequal, largest one ca. 8 mm wide, apex acute to obtuse, two smallest 2–2.5 mm wide, straight to ascendent, apex acute, locular region ca. 5 × 5 mm, broadly ovate, glabrous, seeds oblong.

Etymology: —The specific epithet refers to the type locality, Serra dos Órgãos, a place with high mountains.

Phenology: —Flowering April and fruiting September.

Distribution and ecology: —This species is a narrow endemic known only from the type locality, the upper part of Serra dos Órgãos National Park, in the municipality of Teresópolis, Rio de Janeiro state, between 22°26’50”S 43°0’33’W and 22°26’50”S 43°0’36”W. It has been recorded from two populations occurring along trail that begins at the park’s headquarters in Teresópolis, at elevations from 1373m to 1700 m. In this trail it is possible to follow the transition between the exuberant Atlantic Forest to the high-altitude grasslands. Begonia altimontana grows in montane forests and high montane forests, in shady and humid valleys, on rocks and occasionally on land.

Provisional conservation assessment:— Because it is known only from two populations in one location with a restricted area of occupancy, this species is provisionally assessed as Vulnerable (VUD2) under IUCN Red List criteria ( IUCN Standards and Petitions Committee, 2019).

Additional specimen examined (paratype): — BRAZIL. Rio de Janeiro: Teresópolis, Parque Nacional da Serra dos Órgãos, trilha para o Abrigo 4 e Pedra do Sino , 1700m elevation, 14 September 2007, L. Sylvestre 2144 et al. ( RBR 56197!, RB!) .

Taxonomic notes:— Begonia altimontana is a delicate herb and can be easily recognized by having reddish petioles 7–10 cm long, with diminutive flat fimbriate scales distributed along the entire length, scales 0.5–2 mm long, transversely ovate blades, (5–)7.5–11 × (3–) 6–7 cm, entire, adaxial leaf surface glabrous, abaxial leaf surface with simple and 2-branched trichomes along the entire surface and flat fimbriate scales on principal veins, ca. 0.5 mm long, staminate flowers with glabrous tepals and pistillate flowers with sparsely microscopic glandular trichomes on the tepals and ovary with bilamellate placentae. Begonia altimontana is similar to B. ramentacea Paxton (1846: 73) and Begonia princeps A.DC. (1861: 357) , both endemic species for Rio de Janeiro state, in its rupicolous habit, prostrate stems, squamulose petioles, transversely ovate leaf blades, leaf blades glabrous adaxially and tepals of pistillate flowers with entire margins. However, B. altimontana differs from B. princeps in having an abaxial leaf surface with simple and 2-branched trichomes along the entire surface and squamulose on principal veins, flat fimbriate scales (vs. sparsely pilose) and bilamellate placentae (vs. entire) and from B. ramentacea by having shorter petioles, 7–10 cm long (vs. 12– 25 cm), with flat fimbriated scales, 0.5–2 mm long (vs. laminar at the base and fimbriate at the margins, curved inward, shell-shaped, 2–2.5 mm) and bilamellate placentae (vs. entire). Begonia altimontana also has similarities to Begonia itaipeensis E.L. Jacques (2019: 57) and B. olsoniae L.B.Sm. & B.G.Schub. (1965: 250) in having unequal capsule wings. B. itaipeensis has an adaxial leaf surface with 2-branched trichomes (vs. glabrous), three tepals on pistillate flowers (vs. 4), and entire placentae (vs. bilamellate). Begonia olsoniae is easily distinguished by being densely pilose on the adaxial leaf surface (vs. glabrous) and entire placentae (vs. bilamellate).

Figures

FIGURE 1. A–L. Begonia altimontana E.L.Jacques. A, Habit, showing inflorescence; B, Details of indumentum of petiole; C, Apex in adaxial leaf surface; D, Apex in abaxial leaf surface; E, Trichomes; F, Scales; G, Stipules; H, Staminate flower; I, Stamens J, Pistillate flower, front view; K, Stigmas; L, Pistillate flower, side view. Illustration by Maria Alice Rezende from T.C. Alves 31.

FIGURE 2. A–B. Begonia altimontana E.L.Jacques. A, Habit, showing inflorescence; B, Details of inflorescence, showing staminate and pistillate flowers. (A–B from T.C. Alves 31. (A= 2 cm; B= 1.5 cm). A–B Photos T.C. Alves.

FIGURE 3. Distribution map of Begonia altimontana (rhombus). Dark line indicates the limits of area of the Serra dos Órgãos National Park.