Begonia pseudodendron Moonlight & Á.J.Pérez, 2022

Moonlight, P. W. & Pérez, Á. J., 2022, Begonia (sect. Ruizopavonia) De Candolle 1859, Edinburgh Journal of Botany 79 (401), pp. 1-9 : 3-7

Begonia pseudodendron Moonlight & Á.J.Pérez , sp. nov. § Ruizopavonia

Begonia pseudodendron is most similar to B. cuatrecasasiana L.B.Sm. & B.G.Schub. but differs in its white to pink, glabrous tepals (versus orange tepals that are sparsely pilose on the outside), the rounded apices of its staminate tepals (versus long acuminate apices), and its pistillate flowers with two tepals (versus three) and that lack bracteoles.

– Type: Ecuador, Carchi Province, Trail beginning above Rafael Quindí Finca, above Untal (along road to Chical), and partly ascending Cerro Oscura , 0°52′N, 78°09′W, 1670 m, 26 xi 1987, W.S. Hoover & S. Wormley 1651 (holotype MO [ MO-2256936 ], isotype QCA [QCA-19712] ). Figure 1 .

Caulescent terrestrial herb, lacking a tuber or rhizome. Stem erect or scrambling, to 10 m tall, woody at the base, frequently branching, internodes 2–10 cm, 4–6 mm in diameter, glabrous, smooth, green-flushed red, browning with age. Stipules early deciduous, lanceolate, 2.5–10 × 0.5–4 mm, apex acute, margin entire, aciliate. Leaves alternate, basifixed, straight; petioles joining blade in the direction of the main vein, 2–11 mm long, glabrous; blade subsymmetrical, oblanceolate to elliptic, 7.5–16.5 × 3–6.2 cm, apex short-attenuate, base decurrent, rounded on the broad side of the lamina, cuneate on the narrow side of the lamina, margin entire, serrate towards the apex, ciliate, upper surface green, glabrous, lower surface glabrous, green, pinnately veined, 7- to 9-veined on the broad side of the lamina, 5- to 7-veined on the narrow side of the lamina. Inflorescences: many, axillary but often appearing terminal, arising close to the apex of the stem, erect, a 6–8 times dichotomous cyme, protandrous; peduncle 1.5–4.5 cm long, internodes elongate,> 10 mm long, glabrous, pale green–flushed red; pedicels of staminate flowers 5–15 mm long, glabrous, white to pale green; pedicel of pistillate flowers 9–18 mm long, glabrous, white to pale green; bracts early deciduous, unknown. Staminate flowers: tepals 4, white to pink, outer two ovate, 3–6 × 2–4 mm, apex rounded, margin entire, glabrous; inner two narrowly oblanceolate, c.4 × 1.5–2 mm, apex rounded, margin entire, glabrous; stamens c.20, free, filaments 0.2–0.4 mm long, anthers symmetrically basifixed, oblong, 1–1.5 mm long, dehiscing via lateral slits, connectives extended to 0.2 mm. Pistillate flowers: bracteoles lacking; tepals deciduous in fruit, 2, projecting, white or pink, ovate to lanceolate, 4–12 × 3–10 mm, apex rounded, margin entire, glabrous; ovary body narrowly ovoid, 2–4 × 1–2 mm, white, glabrous, 3-winged, wings white, unequal, largest wing band-like to triangular, apex obtuse, margin entire to lacerate, 4–5 mm tall, 3–8 mm wide, smaller two wings semicircular, margins entire, apex rounded, 4–5 mm tall, 0.5 mm wide; 3-locular, placentae axile bifid, bearing ovules on both surfaces; styles 3, free, 3–6 mm long, bifid from half their length and swollen at the bifurcation, stigmatic papillae in a twice-twisted spiral band. Fruiting pedicel to 24 mm long. Fruit pendant, body broadly ovate, expanding to 8 × 4 mm, light brown, glabrous, largest wing expanding to 12 × 20 mm, triangular, ascending, shorter two wings expanding to 10 × 2 mm. Seeds unknown.

Distribution and ecology. Known from Nariño Department in Colombia and Carchi Province in Ecuador. Found in lower and middle-elevation montane forest of the Andean Chocó region at an elevation of 600–1700 m ( Figure 2 ). Begonia pseudodendron is a large, scrambling species most frequently found on the edge of dense montane forests remnants or in open areas. According to the Ministerio del Ambiente de Ecuador (2013), the type locality and surrounding areas lie within a much larger zone dominated by Bosque siempreverde piemontano de Cordillera Occidental de los Andes (BsPn01, evergreen lower montane forest of the western Andean cordillera). The characteristic tree species of this area include Magnolia mindoensis A.Vázquez, D.A.Neill & A.Dahua , Vochysia awasensis Huamantupa , Isertia pittieri (Standl.) Standl. and the palm Wettinia quinaria (O.F.Cook & Doyle) Burret.

This area is extremely humid, and most tree trunks are covered by bryophytes, orchids, bromeliads and aroids.

Phenology. Begonia pseudodendron has been collected in flower from August to January and in fruit from August to November.

Etymology. The epithet is from the Greek pseudo (‘false’) and dendron (‘tree’) and refers to the species’ habit and the height it can reach: about 10 m tall, achieved by scrambling through surrounding vegetation.

Proposed IUCN conservation category. The known extent of occurrence of Begonia pseudodendron is <1000 km 2 and includes no protected governmental areas in either Colombia or Ecuador; however, it has been collected in a private reserve managed by the Ecominga Foundation, which protects forest remnants around the Chical area in Ecuador. The species’ range appears to include a large extent of original vegetation, but there has been significant and recent deforestation due to farming and road-building in the border region. We have no information on the population size of Begonia pseudodendron so assess the species as Endangered (ENB1abiii) based on its small range and the reduction in suitable habitat.

Additional specimens examined. COLOMBIA. Nariño Department: Municipio de Ricaurte, Resguardo Indigena Nulpe Medio , camino al basal, 1°6′N, 78°13′W, 760 m, 7 i 1996, B. R. Ramírez P. & M. S. González 9506 ( QCA [ QCA235167 ]) ; Mpio. Barbacoas, corregimiento Altaquer, Vereda El Barro, Reserva Natural Río Nambi , 1°18′N, 78°8′W, 1325 m, 5 xii 1993, P. Franco, D. Giraldo, W. Beltrán, A. Prieto & O. Rivera 2926 ( COL [ COL000137627 ]) ; Altaquer , [1°15′S, 78°7′W], 3500 ft, M. B. Foster & R. Foster 2110 ( COL [ COL000137625 ]) .

EcUADOR. Carchi Province: San Marcos Valley, farmland and rainforest disturbed by the local Coaiquer (Awa) Amerindians , 1°7′N, 78°22′W, 600 m, 20–24 xi 1983, A. S. Barfod, L. P. Kvist & D. Nissen 48818 ( MO [MO-098158], QCA [ QCA19633 ], QCNE) ; ibid., A. S. Barfod, L. P. Kvist & D. Nissen 48819 (MO [MO-098159], QCA [QCA19634]) ; Near encampment in Gualpi Chico area of Awá Reserve, 0°58′N, 78°16′W, 1330 m, 20 i 1988, W. S. Hoover, A. Arguello, P. Gelpi & R. A. Lorentzen 2847 ( MO [MO-1956278], QCA [ QCA19427 ]) ; Along bank of Quebrada Mongon at point where Scott finished on 11/18/88, 0°58′N, 78°16′W, 1200–1400 m, 19 i 1988, W. S. Hoover, A. Arguello, P. Gelpi & R. A. Lorentzen 2948 (MO [MO-2364070], QCA [QCA19428] ); Trail to Pilon encampment, Gualpi Chico area of Awá Reserve , 0°58′N, 78°16′W, 1350–1400 m, 21 i 1988, W. S. Hoover , A. Arguello , P. Gelpi & R. A. Lorentzen 3613 ( MO [MO-2364072], QCA [ QCA19431 ]) ; ibid., 1000–1450 m, 14 i 1988, W. S. Hoover, P. Gelpi, R. A. Lorentzen & A. Arguello 2416 ( QCA [ QCA19657 ]) ; South on main trail from camp (away from Pylus) for 1/ 12 m mile from camp East down to río Gualpi Chico , 0°58′N, 78°16′W, 1100 m, 21 i 1988, W. S. Hoover , A. Arguello , P. Gelpi & R. A. Lorentzen 3018 ( MO [MO-1956276], QCA [ QCA19429 ]) ; South-east trail, primary forest in Gualpi Chicó area of Awa reserve , near encampment, 0°58′N, 78°16′W, 1330 m, W. S. Hoover , A. Arguello , P. Gelpi & R. A. Lorentzen 2804 ( QCA [ QCA19426 ]) ; Tulcán Canton, Reserva Indígena Awá, Parroquia Tobar Donoso, sector El Baboso, 0°53′N, 78°20′W, 1600 m, 3 x 1991, G. Tipaz, D. Rubio & M. Taucuz 308 (MO [MO-2907067]); Trail from Untal to Rafael Quindís Finca , south of Cerro Golondrinas , 0°55′N, 78°15′W, 1700 m, W. S. Hoover & S. Wormley 1444 ( MO [MO-2194164], QCA [ QCA19711 ]) ; Cantón Tulcan, Parroquia Chical, Reserva Cerro Colorado, 0°54′N, 78°12′W, 1550–1850 m, 21 viii 2016, A. J. Pérez, N. Zapata, H. Yela & W. Santillán 9728 ( QCA) ; Trail from Rafael Quindís finca to río Verde and along río Verde , 0°53′N, 78°8′W, 1700 m, 26 xi 1987, W. S. Hoover & S. Wormley 1731 ( MO [MO-2186975]) .

Most specimens of Begonia pseudodendron Moonlight & Á.J.Pérez cited here were previously identified as Begonia holtonis A.DC. , which is a distantly related member of Begonia sect. Lepsia (Klotzsch) A.DC. but with a similar habit and similar-shaped leaves ( Moonlight et al., 2018). These two species can be distinguished by the number of tepals in the pistillate flowers, which is two in Begonia pseudodendron and five in B. holtonis .

Begonia pseudodendron is part of a group of species in Begonia sect. Ruizopavonia that have four tepals on the staminate flowers and elongate inflorescence internodes. We provide a key to all Colombian and Ecuadorian species of Begonia sect. Ruizopavonia and a table to aid in distinguishing between similar species (Table). We suspect that Begonia pseudodendron is most closely related to B. cuatrecasasiana on account of its very similar straight, oblanceolate to elliptic leaf blades. We have been unable to confirm the texture of these leaves in the field, but they appear relatively coriaceous whereas several other species in this group have semisucculent leaves (e.g. Begonia consobrina and B. cymbalifera ). Although the flowers of the new species are more similar to those of all other species in the group, we suspect this is indicative of rapid, recent adaptation to a hummingbird pollination syndrome in Begonia cuatrecasasiana rather than a distant relationship.

Figures

Figure 1. Begonia pseudodendron Moonlight & Á.J.Pérez, sp. nov. A, Habit, showing the leaves and a mature, pistillate inflorescence; B, inflorescence, showing pistillate flowers; C, staminate flower, front view; D, fruit, side view. Estimated scale bars: A, 10 cm; B, 5 mm; C and D, 1 cm. Photographs taken by Á. J. Pérez as part of the collection Á.J.Pérez 9728.

Figure 2. Distribution of Begonia pseudodendron Moonlight & Á.J.Pérez (red), B. consobrina Irmsch. (green), B. cuatrecasasiana L.B.Sm. & B.G.Schub. (blue), B. cymbalifera L.B.Sm. & B.G.Schub. (orange) and B. dugandiana L.B.Sm. & B.G.Schub. (black). Black lines indicate country borders; grey lines, firstorder administrative divisions; and blue lines, major rivers. Shading indicates altitude. All distribution records are available through the Begonia Resource Centre (Hughes et al., 2015–). BRA, Brazil; COL, Colombia; ECU, Ecuador; PAN, Panama; PER, Peru; VEN, Venezuala.