Begonia tepuiensis Moonlight & Jara, 2017

Moonlight, P. W. & Jara-Muñoz, A., 2017, A revision and recircumscription of Begonia Section Pilderia including one new species, Phytotaxa 307 (1), pp. 1-22 : 18

6. Begonia tepuiensis Moonlight & Jara spec. nov. ( Fig. 6 ., Fig. 7f )

Begonia tepuiensis is most similar to B. buddleiifolia but is distinguished from that species by its unbranched habit ( B. buddleiifolia has frequently-branching stems); larger leaves to 18 cm (those of B. buddleiifolia rarely exceed 12 cm); its internodes, petioles, and inflorescences that are densely lanate throughout (those of B. buddleiifolia are sparsely to densely lanate); its lateral inflorescence with only cymose lateral branches branching one time (lower lateral branches in B. buddleiifolia are tyrsoid with lateral cymose branches branching two to four times); and its longer, lanceolate bracteoles from 8 to 9 mm (those of B. buddleiifolia are ovate and to 5 mm).

Type: VENEZUELA. Amazonas: Serranía Parú, Cerro Parú: top camp to caño camp, alt. ca. 1200 m, 13 February 1951, R.S. Cowen & J.J. Wurdack 31443 (holotype MO [MO-036500], isotype NY [NY02497219]).

Plants caulescent, rhizomatous herbs, 15–40 cm high; stem repent, rooting at the nodes, flexuous, unbranched; internodes to 1 cm long and rhizomatous at the base of the stem, woody, to 0.75 cm thick, to 3 cm long and trailing towards the apex, to 0.5 cm thick, succulent, very densely lanate, hairs to 1.5–2 mm, red; stipules persistent, ovate, 8–12 × 4–5 mm, apex acute, margins entire, densely ciliate, cilia recurved. Leaves alternate, clustered towards the apex of the stem, less than 5, basifixed; petioles 1–1.5 cm long, very densely lanate, hairs 1.5–2 mm, red; lamina asymmetric at the base, straight, oblique, lanceolate, 8–18 × 3–5.5 cm, apex acuminate, base cuneate on the narrow side of the blade, rounded on the wide side of the blade, acuspidate, margins double-dentate, teeth 0.5–2 mm long, densely long-ciliate, the upper surface bullate, with 5 to 15 dense, glandular-pilose hairs between each tertiary vein connected to one to four three-fid to eight-fid glands visible within the leaf lamina between each tertiary vein, the glands drying black, the veins sparsely lanate to densely lanate towards the petiolar insertion, the lower surface densely glandular-pilose between the tertiary veins, the veins very densely lanate; venation pinnate, with ca. 15 lateral veins on the widest side of the lamina, and ca. 10 lateral veins on the narrow side. Inflorescences: axillary, terminal, erect, to 18 cm, very densely lanate throughout, thyrsoid with 6–10 lateral branches, lateral branches cymose, branching 1 time, protandrous; peduncle to 8 cm long, internodes to 3 cm long, decreasing to ca. 5 mm long at the apex, peduncles of cymes 2–5 mm; bracts persistent, ovate, 4–5 × 2–4 mm, membranous, glabrous, apex obtuse, margin lacerate, ciliate; pedicels of male flowers ca. 4 mm long, fibrous; pedicels of female flowers 8–12 mm long, fibrous. Male flowers: tepals known only from bud, membranous, glabrous, the margins entire, aciliate, the outer 2 ovate, 4 × 2.5 mm, apex acute, white, the inner unknown and perhaps non-existent; stamens unknown. Female flowers: bracteoles 2 persistent, lanceolate, 8–9 × 2–2.5, membranous, villous outside, glabrous inside, margins serrate, densely ciliate; tepals 5, persistent in fruit, same colour as males, subequal, lanceolate to ovate, 6–9 × 2–4, margins entire, ciliate; ovary body globose, 4.5–7 × 4–6 mm, sparsely pilose, 3-locular, unequally 3-winged, largest wing triangular, not ascending, widest 1/3 of the length towards the apex, 5–12 × 6–7 mm, apex acute, base cordate to rounded, the upper margin entire, ciliate, the lower margin lacerate, ciliate, smallest 2 marginiform, 1–2 mm wide, rounded; placentae axile, simple, ovuliferous all over; styles 3, 4–5 mm long, bifid 2 mm from base, the branches erect, spirally twisted two to three times, persistent in fruit. Fruiting pedicel as the female flowers. Fruit ovate, enlarging to 8 × 7 mm, largest wing the same shape as in the ovary, enlarging to 12 × 12 mm, the smallest enlarging to a triangular wing 9 × 5 mm. Seeds globose, 0.2 × 0.2 mm.

Distribution and habitat:— Veneuela. Known only from talus slopes at ca. 1200 m on the Cerro Parú Tepui in the Amazonas province of Venezuela.

Etymology:— The genus Begonia is relatively poorly known from the tepuis of northern Amazonia. We name this species B. tepuiensis as it is only the third Begonia species described exclusively from tepuis after B. steyermarkii L.B.Sm. & B.G.Schub and B. nubicola L.B.Sm. & B.G.Schub.

IUCN Redlist Assessment:— No information is available about population size or trends in Begonia tepuiensis , which is known from only a single site. Accordingly, we assess B. tepuiensis as Vulnerable (VU D2).

Figures

FIGURE 6. Begonia tepuiensis Moonlight & Jara. A. Habit, flowering top; B. Habit, shoot with rooting nodes; C. Female flower (side view); D. Stigma (front view); E. Stigma (back view); F.Bract; G. Detail of leaf hairs, upper lamina; H. Detail of leaf hairs, lower lamina. Drawn from type collection R.S. Cowen & J.J. Wurdack 31443 by Claire Banks.

FIGURE 7. Distributions of species in Begonia sect. Pilderia (Klotzsch) A.DC. A. B. buddleiifolia A.DC.; B. B. glandulifera Griseb.; C. B. humillima L.B.Sm. & Wassh.; D. B. jenmanii Tutin; E. B. mariannensis Wassh. & T.McClellan; F.B. tepuiensis Moonlight & Jara.