Begonia cunhambebii E.L.Jacques, 2020

Jacques, Eliane De Lima, 2020, Two new Brazilian species of Begonia (Begoniaceae) from Atlantic Coastal Forest, Phytotaxa 432 (1), pp. 38-46 : 38-39

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

Begonia cunhambebii is most similar to B. friburgensis Brade but differs by lanate indumentum (vs. lanuginose), bracteoles 2, widely ovate, overlapping each other at the base of the ovary (vs. bracteole 1, linear, not overlapping at base of the ovary) and by male flowers with ovate outer tepals (vs. oblong-triangular).

Type:— BRASIL. Rio de Janeiro: Mangaratiba, Serra do Piloto, Parque Estadual do Cunhambebe, Estrada São João Marcos, margem da RJ 149, 22°54´39”S, 44°01´06.6” W, 197 m, 9 December 2014, Jacques with Santos Junior 1921 (holotype RBR!, isotype RB!).

Description:—Herbs, erect, robust, rupicolous, ca. 0.5 m tall (excluding the inflorescence), lanate. Cystoliths absent. Stem prostrate, with internodes reddish, 1–2 cm long, lanate. Stipules persistent, ovate, ca. 2.5 × 1.5 cm, scarious, brown, apex acuminate, carinate, lanate. Leaves simple, petioles half-terete, greenish to ferruginous, 18– 40 cm long, lanate, with stellate trichomes along the entire length, leaf blades basifixed, entire, transversely ovate, asymmetrical, sub-coriaceous, 19–30 × 14–23 cm, adaxial surface glossy greenish, glabrous, abaxial surface reddish, ferruginous, lanate, stellate trichomes, 3–5-branched, adpresed, densely distributed on the primary veins, margins entire, apex acuminate, base cordate, lobes overlapping the petiole, venation actinodromous, veins 5–6. Inflorescences in 6-branched cyme, ca. 40 cm long (up to ca. 103 cm long when fruiting), rachis vinaceous, ca. 35 cm long (up to ca. 91

cm long when fruiting), bracts caducous. Male flowers ca. 10 mm long, pedicels vinaceous, ca. 5–7 mm long, glabrous; tepals 4, external pairs white, with pink margins, ovate, 9–11 × 8–10 mm, one of the pairs ca. 2 mm longer than the other, apex obtuse to rounded, glabrous, internal pairs white, elliptic, ca. 6 mm × ca. 2 mm, glabrous, stamens 13–14, free, ca. 4 mm long, anthers yellow, elliptic, ca. 3 mm long (including connective), rimose, with frontal openings, extrorse, filaments ca. 1 mm long. Female flowers ca. 20 mm long, pedicels ferruginous, ca. 10 mm long, puberulous, bracteoles 2, hot pink in proximal region to pink distally, widely ovate, 7–8 × 10 mm long, overlapping each other at the base of the ovary, with 2-branched trichomes, tepals 5, white, ovate, 11–14 × 7–10 mm, with two-armed trichomes, ovary 3–locular, stigmas 3, branches spiraled, yellow, 3–4 mm long, ovary pink, 6–7 × 7–8 mm (including the wings), glabrous, wings hot pink, placentae entire. Capsules 13 × 15–17 mm (including the wings), peduncles 18–20 mm long, puberulous, wings brown, subequal, the largest one rounded, locular region elliptic, ca.10 × 6 mm, brown, glabrous, seeds oblong.

Etymology:—The specific epithet refers to a chief of the Tamoios tribe, Cunhambebe, whose name was given to the park where the holotype was encountered.

Phenology: —Flowering and fruiting between December and May.

Distribution and ecology: — Begonia cunhambebii is known only from the type locality, the Serra do Piloto highway (RJ 149), Parque Estadual do Cunhambebe, in the municipality of Mangaratiba, southern region of Rio de Janeiro State, Brazil. Serra do Piloto is the first highway of Brazil, formerly known as Estrada Imperial de Mangaratiba. The highway was constructed by slaves in 1855 to drain coffee plantations, and there are original stones in some parts of it. This species grows in submontane forests, at elevation between of 197 to 208 m asl, in shady localities, on rocky slopes and outcrops on roadside, about 5 m from watercourses. The species is known from one population with approximately 100 individuals in an area of 15 m ². Accordingly, B. cunhambebii is provisionally assessed as Vulnerable (VU D2) under IUCN Red List criteria ( IUCN Standards and Petitions Committee, 2019).

Additional specimens examined (paratypes):— BRAZIL. Rio de Janeiro: Mangaratiba, Serra do Piloto, Parque Estadual do Cunhambebe, Estrada São João Marcos, RJ 149, 22°54´39”S, 44°01´06.6” W, 197 m, 29 May 2019, Jacques with Praxedes & Silva 2034 (paratype RBR!, isoparatype RB!).

Taxonomic notes:— Begonia cunhambebii can be easily recognized by having very long petioles, 18–40 cm long, half-terete, transversely ovate blades, 19–30 × 14–23 cm, abaxially lanate, ferruginous, with adpressed stellate trichomes (3–5-branched), densely distributed on the primary veins, lobes of blades overlapping the petiole, inflorescence a 6-branched cyme, male flowers with ovate external tepals, with obtuse to rounded apex, female flowers with two bracteoles, widely ovate, overlapping for each other at the base of the ovary, fruits with the largest wing rounded. Begonia cunhambebii is similar to B. friburgensis Brade (1957: 31) and B. fluminensis Brade (1945: 30) which share a repent habit on rocky slopes and outcrops in different areas of Atlantic forest ( Brade 1945, 1957), shape of leaves and stellate trichomes. B. cunhambebii resembles B. fluminensis due the lanate indumentum, cordate leaf base, male flowers with ovate external tepals, with obtuse to rounded apex and fruits with the largest wing rounded at apex. B. fluminensis , however, is different because it is a delicate herb (vs. robust) and the lobes of leaves are not overlapping at the petiole (vs. lobes overlapping the petiole). B. cunhambebii resembles B. friburgensis by lobes of blades overlapping the petiole, but B. friburgensis has lanuginose indumentum (vs. lanate, ferruginous), male flowers with oblong-triangular external tepals (vs. ovate), with acuminate apex (vs. obtuse to rounded), and fruits with the largest wing acute at apex (vs. rounded).

Figures

FIGURE 1. A–F. Begonia cunhambebii E.L.Jacques. A, Habit, showing inflorescence and infructescence; B, Details of petiole (cross section); C, Details of indumentum on the abaxial leaf surface; D, Trichomes on the bracteoles; E, Leaf trichome; F, Male flower bud; G, Male flower; H, Stamen; I, Bracteole of the female flower; J, Female flower, front view; K, Female flower, lateral view; L, Female flower showing overlapping bracteoles at the base of the ovary; M, Stigmas; N, Ovary in cross section; O, Capsule. Illustration by Maria Alice Rezende from E.L. Jacques et al. 1921 (A–C, E–H, O) and E.L. Jacques et al. 2034 (D, I–N).

FIGURE 2. A–F. Begonia cunhambebii E.L.Jacques. A, Habitat; B, Details of habit showing leaf and inflorescence during early development, petioles and stipules; C, Indumentum on the abaxial leaf surface; D, Inflorescence showing male flowers; E, Details of inflorescence showing female flowers; F, Immature fruits. (A–D from E.L. Jacques et al. 1921; E–F from E.L. Jacques et al. 2034). (A= 30 cm; B= 3 cm; C= 2.5 cm; D= 5 mm; E= 10 mm; F= 8 mm). A, E–F Photos A.C. Praxedes; B–D Photos J. Wesenberg.

FIGURE 3. Distribution map of Begonia cunhambebii E.L.Jacques (circle). Green shading indicates the limits of the Cunhambebe State Park.