Begonia yuracyacuensis Moonlight, 2023

Moonlight, Peter. W., Jara-Muñoz, Orlando A., Purvis, David A., Delves, Jay, Allen, Josh P. & Reynel, Carlos, 2023, The genus Begonia (Begoniaceae) in Peru, European Journal of Taxonomy 881, pp. 1-334 : 276-279

69. Begonia yuracyacuensis Moonlight sp. nov.

urn:lsid:ipni.org:names:77323297-1

Figs 6C , 84A , 87

Diagnosis

Most similar to B. peruviana but differing in its inflorescences that branch up to 4 times (vs 6 to 8 times); its subequal, obdeltoid fruit wings with straight sides (vs unequal wings, the largest obdeltoid with rounded sides, the smallest ridgelike); its broadly ovate bracts and bracteoles (vs elliptic bracts and linear to ovate bracteoles); its larger staminate tepals (10–14 × 10–15 mm vs 2–5.5 × 2–6.5 mm); and its styles, which are thickened at the bifurcation (vs not thickened).

Etymology

The name refers to the río Yuracyacu, which flows through the Boquerón de Padre Abad. This means the ‘white river’ in Quechua.

Type

PERU – San Martín Region: Prov. Coronel Portillo • Vicinity of Aguaytía, Boquerón de Padre Abad ; [9°04′ S, 75°41′ W]; [300 m a.s.l.]; 1 Aug. 1962; M.E. Mathias & D. Taylor 6096; holotype: USM; isotype: MO [ MO-1641350 ].

Specimens examined

PERU – San Martín Region: Prov. Rioja • Dist. Nuevo Cajamarca, cerca del Poblado Palestina , camino a la Cueva Palestina; 5°54′ S, 77°21′ W; 890 m a.s.l.; 1 Nov. 1996; I. Sánchez Vega & M.O. Dillon 8389; CPUN, F [ V0086778F ], US [ US00673143 ]. – Ucayali Region: Prov. Coronel Portillo • Dist. Padre Abad, Boquerón de Padre Abad ; 9°04′ S, 75°41′ W]; 300 m a.s.l.; 8 Aug. 1946; G. Woytkowski 34341; G [2: 1 mixed sheet], MO [ MO-1641413 , mixed sheet] • ibid.; 500 m a.s.l.; 10 Sep. 1980; P.J.M. Maas, L. Cobb & E.H.M. Grothe 4574; U, US [ US00967205 ], USM • ibid.; 17 Aug. 1946; R. Ferreyra 1147; MO [ MO-2264390 ], US [ US00967391 ], USM • ibid.; 500–550 m a.s.l.; 2 Oct. 1950; R. Ferreyra 8110; MO [ MO-2264395 ], MOL, US [ US00967204 ], USM [2] • ibid.; 9°04′01″ S, 75°40′46″ W; 403 m a.s.l.; 8 Feb. 2016; P.W. Moonlight & A. Daza 199; E [ E00885477 ], MO, MOL • ibid.; 470 m a.s.l.; 8 Aug. 1946; F. Woytkowski 341; USM • Dist. Iparía, Cuenca del río Iparía , afluente del río Ucayali, reserva Comunal el Sira ; 9°26′14″ S, 74°33′30″ W; 400–450 m a.s.l.; 5 Oct. 2007; J.G. Graham 4898; MOL, US [ US01008606 ] . – Cultivated • Grown in the Royal Botanic Garden Edinburgh from P.W. Moonlight & A. Daza 199 RBGE Living Accession 20160139; 22 Mar. 2021; P.W. Moonlight 1952; E.

Description

Caulescent herb, to at least 1 m high. Stem erect, frequently branching; internodes to 5 cm long, to 6 mm thick, succulent, green to red at the nodes, glabrous. Stipules early deciduous, lanceolate, 8–14 × 2–4 mm, apex acuminate, translucent, pale green, glabrous, margin entire, aciliate. Leaves> 5, alternate, basifixed; petiole 0.5–1.7 cm long, pale green to red, glabrous; blade subsymmetric, oblong, to 12 × 6.5 cm, succulent, apex short acuminate, base inequilateral, cuneate to rounded on the narrow side of the bade, rounded on the broad side of the blade, margin serrulate, ciliate, upper surface dark green, often with red or purple spots on young leaves, glabrous, though young leaves often with a single hair at the centre of each coloured spot, lower surface pale green, glabrous, veins pinnate with 9–12 secondary veins on the larger side, 8–12 secondary veins on the smaller side. Inflorescences> 3, bisexual, axillary, erect, cymose, branching up to 4 times, bearing up to 8 staminate flowers and 8 pistillate flowers, protandrous; peduncle to 2.8 cm long, pale green, glabrous, bracts deciduous, ovate, ca 4 × 3 mm, translucent, white to pink, glabrous, apex acute, margin serrulate towards the apex, ciliate. Staminate flowers: pedicels to 13 mm long, glabrous; tepals 2, spreading, broadly ovate, 10–14 × 10–15 mm, apex rounded, white, glabrous, margin entire, aciliate; stamens ca 35, projecting, yellow, filaments 0.2 mm long, free, anthers elliptic, 1–1.5 × 0.8 mm long, dehiscing via lateral slits, connectives extending to 0.5 mm, symmetrically basifixed. Pistillate flowers: pedicels to 13 mm long; bracteoles 2, directly beneath the ovary, broadly ovate, 5–7 × 4–6 mm, apex rounded, translucent, white flushed pink, glabrous, margin serrulate at the apex, ciliate, tepals 2, equal, deciduous in fruit, spreading, ovate, 8–11 × 8–12 mm, apex rounded, white, glabrous, margin entire, aciliate; ovary body ovoid, 8–9 × 4–6 mm, white, glabrous, sub-equally 3-winged, the largest wing obdeltoid, 8–12 × 10–13 mm, the smallest obdeltoid, to 12 × 8 mm wide; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow, free, ca 4 mm long, once-divided, thickened above the division, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 18 mm long. Fruit body ovoid, to 12 × 7 mm, drying brown, wings same shape as in ovary, the largest expanding to 16 × 13 mm, the smallest to 14 × 16 mm.

Proposed conservation assessment

Known from localities approximately 125 km apart in Ucayali Region Peru and a third locality in San Martín Region. These three localities are low lying, extremely humid hills. Similar localities elsewhere are poorly explored in Peru, so it is likely found elsewhere. However, because it is only known from three localities, we assess B. yuracyacuensis sp. nov. as Vulnerable (VU D2), owing to the proximity of two of its collections to major roads and the widescale deforestation in lowland montane forests in Amazonian Peru.

Notes

The label of the type collection states it was collected in San Martín Region. The locality description refers however to the Boquerón de Padre Abad, which is in Ucayali Region.

Identification notes

When in flower and fruit, it is trivial to distinguish the new species from B. peruviana based upon its fewer-branched inflorescences (up to 4 times branching vs up to 8 times branching) and much larger staminate and pistillate flowers (see Diagnosis). The two species are very difficult to distinguish when sterile. The stipules of the new species tend to be broader (2–4 mm wide vs 1–3 mm wide) and the leaf margins of both species can be serrulate but B. peruviana more frequently has serrate or doubly-serrate margins. Finally, the two species differ in their habits. B. peruviana tends to scramble through other plants and reaches up to at least 3 m in height. In contrast, B. yuracyacuensis sp. nov. grows horizontally from vertical cliffs and is self-supporting.

Distribution and ecology

Endemic to Peru and known from San Martín and Ucayali Regions ( Fig. 84A ). Known from an elevation of 300–890 m a.s.l. and collected by the authors within the Boquerón de Padre Abad, a ca 700 m a.s.l. deep gorge in Amazonian Peru, where the río Yuracyacu cuts through a north-south ridge to the west of the Cordillera Azul. This is the most easterly ridge of the Andes in central Peru and therefore one of the wettest locations in Peru. The new species is found growing under and around waterfalls on the walls of the gorge. It has been collected growing in association with B. albomaculata , which is a distantly related species.

Figures

Fig. 6. Styles and stigmas in Peruvian Begonia. A–C. Bifid styles. D. Reniform styles. E–F. Irregularly multifid styles. A. Three styles and stigmas of B. bracteosa A.DC. B. Three styles and stigmas of B. glabra Aubl. C. Single style and stigma of B. yuracyacuensis Moonlight sp. nov. D. Three styles and stigmas of B. pedemontana Moonlight sp. nov. E. Three styles and stigmas of B. obtecticaulis Irmsch. F. Single styles and stigma of B. pleiopetala A.DC. Photographs taken by D.A. Purvis & P.W. Moonlight in the living collections of the Royal Botanic Garden Edinburgh.

Fig. 84. Distribution of Begonia sect. Ruizopavonia A.DC. in Peru and surrounding countries. A. B. glauca (Klotzsch) Ruiz & Pav. ex A.DC. (red) and B. yuracyacuensis Moonlight sp. nov. (blue). B. B. nunezii Moonlight sp. nov. (red) and B. peruviana A.DC. (blue). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 87. Begonia yuracyacuensis Moonlight sp. nov. A. Habit. B. Stipule. C. Leaf, adaxial surface. D. Leaf, abaxial surface. E. Shade leaf, adaxial surface. F. Cross section of ovary. G. Pistillate flower, side view. H. Pistillate flower, front view. I. Pistils, side view. J. Bracteole. K. Staminate flower, side view. L. Staminate flower, front view. M. Androecium, side view. Photographs taken by D.A. Purvis and P.W. Moonlight in the living collections of the Royal Botanic Garden Edinburgh (Accession 20160139, grown from seeds collected as part of P.W. Moonlight & A. Daza 199).