Begonia speculum Moonlight & Tebbitt

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 : 295-296

74. Begonia speculum Moonlight & Tebbitt

Figs 90B , 93

Edinburgh Journal of Botany 74 (2): 112 ( Moonlight & Tebbitt 2016).

– Type: PERU – San Martín Region: Prov. Rioja • Bosque de Protección Alto Mayo (BPAM) , road from Amazonas to Rioja, km 393; 5°40′11″ S, 77°41′24″ W; 1335 m a.s.l.; 2 Feb. 2016; P.W. Moonlight & A. Daza 158; holotype: MOL; isotypes: E [ E00833930 ], MO [ MO-3237363 ], USM.

Etymology

The epithet is the Latin noun ‘ speculum ’, which means ‘mirror’. It refers to the relatively symmetrical leaves of this species.

Specimens examined

PERU – San Martín Region: Prov. Rioja • Road from Pedro Ruiz to Rioja , km 393; 5°40′11″ S, 77°51′23″ W; 1297 m a.s.l.; 4 Jul. 2018; P.W. Moonlight 1261; USM • Bosque de Protección de Alto Mayo (BPAM) ; 5°42′ S, 77°44′ W; 1700–1800 m a.s.l.; 9 Jul. 2010; M.M. Mora & J. Pérez 883; USM.

Description

Caulescent, tuberous herb, to 15 cm high. Tuber sub-globose, 1.5–2 × 1.5–3 cm, with 1 growing points. Stems 4, erect, unbranched; internodes to 4.5 cm long, to 0.5 mm thick, wiry, pink to red, glabrous. Stipules late deciduous, lanceolate, 1–4.5 × 1–2 mm, apex acute, opaque, red to brown, glabrous, margin entire, aciliate. Leaves 2–4 per stem, alternate, basifixed; petiole 0.8–7 cm long, pink to red, glabrous; blade subsymmetric, ovate, to 6.5 × 3.5 cm, succulent, apex acute, base shallowly-cordate, basal lobes not overlapping, sinus to 4 mm deep, margin irregularly crenate, ciliate, upper surface copper to dark green, glabrous, lower surface red, glabrous, veins palmate-pinnate, 5–7 veined from the base, 2–3 veins on the larger side, 2–3 veins on the smaller side. Inflorescences 1–3, bisexual, axillary, erect, cymose, with up to 4 branches, bearing up to 4 staminate flowers and 4 pistillate flowers, protandrous; peduncle to 5.5 cm long, green to red, glabrous, bracts persistent, elliptic to lanceolate, 2–4 × 1–1.5 mm, translucent, pale green, glabrous, apex obtuse, margin entire, glabrous. Staminate flowers: pedicels to 15 mm long, glabrous; tepals 4, spreading, outer 2 elliptic to obovate, 6–7 × 3–4 mm, apex obtuse, white, glabrous, margin entire, aciliate, inner 2 elliptic to oblanceolate, 4–6 × 2.5–3 mm, apex acute to obtuse, white, glabrous, margin entire, aciliate; stamens 15–20, spreading, yellow, filaments 1–3 mm long, fused into a 0.5 mm column, anthers cuboid, 0.5 × 0.5–0.75 mm long, dehiscing via lateral slits, connectives extended 0.1 mm, symmetrically basifixed. Pistillate flowers: pedicels to 20 mm long; bracteoles 2, positioned directly beneath the ovary, elliptic to lanceolate, 2–4 × 1–1.5 mm, apex obtuse, translucent, pale green, glabrous, margin entire, aciliate; tepals 5, subequal, persistent in fruit, spreading, the ovate to obovate, 3.5–6 × 3.5–5 mm, apex obtuse to rounded, white, glabrous, margin entire, aciliate; ovary body cuboid, 3.5–6 × 3.6–6 mm, pale green, glabrous, equally 3-winged, wings marginal, 0.5–1 × 3.5–6 mm; 2- or 3-locular, placentae branches entire, bearing ovules on both surfaces; styles 2 or 3, yellow, free to base, 2–3 mm long, 2-lobed, stigmatic papillae in a spiral band. Fruiting pedicel to 25 mm long. Fruit body globose, to 6 × 6 mm, drying brown, wings same shape as in ovary, expanding to 2.5 mm wide.

Proposed conservation assessment

Assessed by Moonlight & Tebbitt (2016) as Vulnerable (VU D2), based upon its AOO of <8 km 2. A further population has been identified 50 km to the SW of the type locality and one further collection has been made at the type locality (P.W. Moonlight 1261), where the population appeared stable. The AOO of the species is now 12 km 2 and remains within the criteria required for an assessment as Vulnerable (VU D2).

Identification notes

The only tuberous species of Begonia in northern Peru with subsymmetric, ovate leaves. It is also unusual among tuberous Peruvian begonias in its crenate leaf margins and stamens held on a short column.

Distribution and ecology

Endemic to Peru and Rioja Province, San Martín Region ( Fig. 90B ). Found in lower montane forest at an elevation of 1300–1800 m a.s.l. where it grows directly on limestone in the shade of montane forest and with its tuber buried in alkaline soil. Begonia speculum Moonlight & Tebbitt has been collected from two populations in Bosque de Protección Alto Mayo and identified from photographs taken by Wenbo Chen of a third population ca 7.5 km ESE of Nuevo Cajamarca (5°58′17″ S, 77°21′57″ W; [1300 m a.s.l.]). As a tuberous herb, B. speculum presumably has a dormant period but it has been collected in flower and fruit in February and July, so it remains unclear when this is.

Figures

Fig. 90. Distribution of the Begonia sect. Ignota in Peru and surrounding countries. A. B. bifurcata L.B.Sm. & B.G.Schub. (red), B. erythrothrix Tebbitt & Moonlight (red), and B. occultata J.P.Allen & Moonlight sp. nov. (green). B. B. speculum Moonlight & Tebbitt (red), B. thyrsoidea Irmsch., and B. urubambensis Tebbitt (green). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 93. Begonia speculum Moonlight & Tebbitt. A. Habit. B. Staminate flower, front view. C. Pistillate flower, side view. D. Stamen, front view. E. Stamen, side view. F. Pistil, front view. G. Pistil, back view. H. Infructescence. Illustration by Claire Banks from P.W. Moonlight & A. Daza 158 (E). Reproduced from Moonlight & Tebbitt (2016), with the permission of Edinburgh Journal of Botany.