Begonia stenotepala L. B. Sm. & B. G. Schub.

24. Begonia stenotepala L.B.Sm. & B.G.Schub.

Figs 1A, 2D, 5C, 35D, 38

Publications of the Field Museum of Natural History, Botanical Series 13 (4/1): 200 (Smith & Schubert 1941a).

– Type: PERU – Cusco Region • along río Tambomayo, between Tambomayo and Asunción; [13°03′ S, 71°32′ W]; 900–1400 m a.s.l.; 24 Jul. 1936; J. West 7114; holotype: UC [UC578669].

Brako & Zarucchi (1993: 195); León & Monsalve (2006: 169).

Etymology

The name derives from the Greek words, ‘ stenos ’ and ‘ tepalus ’, meaning ‘narrow’ and ‘tepal’ respectively. This refers to the relatively narrow, triangular tepals of both the staminate and pistillate flowers.

Selected specimens examined

PERU – Cusco Region: Prov. La Convención • Dist. Echarate, Kapiromashi, 12°09′48″ S, 72°34′31″ W; 750 m a.s.l.; 25–30 Apr. 2004; N. Salinas, H. Beltrán, R.B. Foster & C. Vriesendorp 6691; US [US002222332], USM. – Prov. Paucartambo • Dist. Kosñipata, pongo de Koñec; 12°53′53″ S, 72°22′25″ W; 700 m a.s.l.; 5 Aug. 2007; I. Huamantupa 10294; MO [MO-2132027] • km 67 of road from Paucautambo to Pilcopata; 13°04′24″ S, 71°33’21′ W; 1784 m a.s.l.; 4 Aug. 2014; P.W. Moonlight & A. Daza 83; E [E00724451], MOL, USM • Valle del Pilcopata, road from Patria to Pillahuata; 13°10′ S, 71°25′ W; 1000–1500 m a.s.l.; 13 Dec. 1983; R.B. Foster & T. Wachter 7465; USM. – Prov. Quispicanchis • hills around río Araza between Pan de Azúcar and Quincemil airport; 13°13′ S, 70°45′ W; 643 m a.s.l.; 10 Aug. 1991; P. Núñez 14129 (MO [MO-2228053], USM • Mandor, Marcapata; [13°21′ S, 70°52′ W]; 1100 m a.s.l.; 15 Jul. 1945; J.C. Vargas Calderón 5242; CUZ • Dist. Marcapata, Quincemil, 13°42′46″ S, 70°59′40″ W; 430–800 m a.s.l.; 23 Oct. 2004; L. Valenzuela, E. Suclli,. V. Chama, J. La Torre 4267; MO [MO-1664172], US [US00900536]. – Madre de Dios Region: Prov. Manu • izquierda Madre de Dios, cerca pongo; [12°62′ S, 71°22′ W]; 670 m a.s.l.; Jun. 1964; J.C. Vargas Calderón 15526; MO [MO-1835898].

Description

Caulescent herb, to 1 m high. Stem erect, rarely branching; internodes to 7 cm long, to 6 mm thick, succulent, pale green to pink, glabrous. Stipules late deciduous to persistent, lanceolate, 12–35 × 5–8 mm, apex acute, translucent, pale green, glabrous, margin entire, aciliate. Leaves 4–8, alternate, basifixed; petiole 2–9 cm long, pale red, glabrous; blade strongly asymmetric, lanceolate to ovate, to 18 × 9 cm, succulent, apex acuminate, base rounded, margin entire to serrulate, aciliate to ciliate, upper surface dark, glossy green, glabrous, lower surface green to deep red, glabrous, veins palmate but with one primary vein, 5–7 veined from the base, with 1–3 secondary veins on the larger side, 1–3 on the smaller side. Inflorescences 1–3, bisexual, axillary, erect, cymose, branching up to 5 times, bearing up to 64 staminate flowers and 16 pistillate flowers, protandrous; peduncle to 12 cm long, red, glabrous, bracts deciduous, ovate, 4–15 × 3–10 mm, opaque, brown, glabrous, apex rounded to acute, margin entire to serrulate, aciliate to ciliate. Staminate flowers: pedicels to 5 mm long, glabrous; tepals 2, projecting, lanceolate, 5–18 × 4–8 mm, apex acuminate, bright red or orange, glabrous, margin entire, aciliate; stamens ca 30, projecting, yellow, filaments ca 0.3 mm long, free, anthers linear, 1.5–2 × 0.5 mm, dehiscing through lateral slits, connectives extended, symmetrically basifixed. Pistillate flowers: pedicels to 15 mm long; bracteoles 3, positioned directly beneath the ovary, ovate, 5–5.5 × 4.5–5.5 mm, apex rounded, opaque, bright red or orange, glabrous, margin lacerate, ciliate; tepals 5, subequal, persistent in fruit, projecting, lanceolate, 5–18 × 2–9 mm, apex acute, bright red or orange, glabrous, margin entire, aciliate; ovary body obovoid, 4–7 × 2–4 mm, bright red or orange, glabrous, unequally 3-winged, wings triangular, largest 5–15 × 4–11 mm, smallest two wings 3–8 × 1–3 mm; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow, free, 3–4 mm long, once-divided, stigmatic papillae in a spirally-twisted band. Fruiting pedicel to 25 mm long. Fruit body ovoid, to 12 × 6 mm, drying brown, wings same shape as in ovary, the largest expanding to 18 × 30 mm, the smallest expanding to 12 × 5 mm.

Proposed conservation assessment

Previously assessed as Data Deficient (DD) by León & Monsalve (2006). The EOO of the species is <5000 km 2, which is sufficiently small for the species to qualify as endangered. Within its range, however, B. stenotepala is common and conspicuous, this species and frequently collected, especially on the borders of the road from Challabamba to Pilcopata, which forms one of the borders of Manu National Park. We estimate from fieldwork in 2014 that the population of B. stenotepala here exceeds> 50 k individuals and suspect similar populations are found within the species’ range, including within Manu National Park, and surrounding, intact forests. We assess B. stenotepala as Least Concern (LC).

Identification notes

Begonia stenotepala is trivial to identify when in flower on account of its staminate and pistillate flowers with vivid red tepals with acute apices. Similar coloured and shaped tepals are found only in distantly related species with completely different habits (e.g., B. polypetala, B. rossmanniae, B. monadelpha). When sterile, B. stenotepala is recognised as an erect herb with transversely ovate leaves and large, persistent stipules. In this respect, it is very similar to B. subspinulosa, but the two species can be distinguished by their leaf margins. Begonia stenotepala has entire to serrulate margins, which are often aciliate and do not look spinescent. In contrast, the leaf margins of B. subspinulosa are serrulate to serrate, always ciliate, with the serrations and ciliate margins appearing superficially sharp.

Distribution and ecology

Endemic to Peru and known from Cuzco and Madre de Dios Regions (Fig. 35D). Found in lower and rarely middle montane Forest at an elevation of 670–1880 m a.s.l. The vivid red flowers of the species and its projecting tepals suggest it may be hummingbird pollinated, but no pollinator records are known. Begonia stenotepala has been collected in flower from April to December with a peak in July and August, which is the dry season.