Begonia arrogans Irmsch.

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 : 208-210

50. Begonia arrogans Irmsch.

Figs 65B , 67

Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 74: 606 ( Irmscher 1949).

– Type: PERU – [Pasco Region: Prov. Oxapampa] • Pichis trail between Azupizú and Santa Rosa ; [10°39′ S, 74°57′ W]; 650 m a.s.l.; 28 Jun.–8 Jul. 1929; E.P. Killip & A.C. Smith 26137; lectotype: US [ US00115245 ], designated by Tebbitt et al. (2018a: 223); isolectotypes: F [ V0042320F ], NY [ NY00112291 ].

Brako & Zarucchi (1993: 191); León & Monsalve (2006: 165); Tebbitt et al. (2018a: 223).

Etymology

The epithet derives from the Latin ‘ arrogans ’, meaning ‘proud’. This presumably refers to the striking colours of the species’ young leaves.

Specimens examined

PERU – Ucayali Region: Prov. Atalaya • Road from Puerto Ocopa to Atalaya , ca km 105; 10°53′23″ S, 73°57′01″ W; 553 m a.s.l.; 15 Feb. 2016; P.W. Moonlight & A. Daza 250; E [ E00885608 ], MOL • Km 53 of road from Puerto Ocopa to Atalaya ; 10°53′50″ S, 74°11′39″ W; 835 m a.s.l.; 14 Feb. 2016; P.W. Moonlight & A. Daza 242; E [ E00885554 ], MOL. – Pasco Region: Prov. Oxapampa • Route from Pozuzo to Codo de Pozuzo ; 10°00′22″ S, 75°30′31″ W; 655 m a.s.l.; 20 Feb. 2016; P.W. Moonlight & A. Daza 285; E [ E00885609 ], MOL • Camino to mirador from Pozuzo ; 10°03′59″ S, 75°32′57″ W; 792 m a.s.l.; 20 Feb. 2016; P.W. Moonlight & A. Daza 277; E [ E00885610 ] • Along road ChatarraCacazu , disturbed forest; 10°32′ S, 75°04′ W; 700 m a.s.l.; 13 Aug. 2003; H. van der Werff 18425; MO [ MO-437477 ]. – Junín Region: Prov. Chanchamayo • ca 9.5 km NW of San Ramón on dirt road along E side of río Oxabamba valley; 11°03′22″ S, 75°24’30″ W, 1042 m a.s.l.; 22 Jun. 2014; P.W. Moonlight & A. Daza 27; E [ E00835499 ], USM. – Prov. Satipo • Road Mazamari–Puerto Ocopa , path to waterfall; 11°17′08″ S, 74°27′45″ W; 610 m a.s.l.; 30 Sep. 2007; R.T. Pennington & A. Daza 1982; E [ E00567574 ] • Route from Mazamari to Puerto Ocapa. Path to catarata Arco Iris , ca 25 m on to trail; 11°18′01″ S, 74°27′26″ W; 562 m a.s.l.; 14 Feb. 2016; P.W. Moonlight & A. Daza 239; E [ E00885547 ], MOL. – Cultivated • Grown in the Royal Botanic Garden Edinburgh from P.W. Moonlight & A. Daza 239 RBGE Living Accession 20160124b; 15 Mar. 2021; P.W. Moonlight 1950; E.

Description

Caulescent herb, to 100 cm high. Stem erect, rarely branching; internodes to 12 cm long, to 20 mm thick, succulent, becoming hardened at maturity, pale brown, glabrous. Stipules late deciduous, oblong-ovate, 11–22 × 4–9 mm, apex acute, setose, opaque, pale green, glabrous, margin entire, aciliate. Leaves 1–5 per stem, alternate, basifixed; petiole 10–20 cm long, green to red, glabrous; blade asymmetric, transversely ovate to oblong-ovate, to 42 × 21 cm, succulent, apex acute to acuminate, base cordate, basal lobes not overlapping, sinus to 55 mm deep, margin with 0–4 irregular triangular lobes, lengthening towards the apex of the leaf, crenate, ciliate, upper surface green, sometimes flushed silver between the veins, glabrous, lower surface pale green to deep red, glabrous, veins palmate-pinnate, 4–6 veined from the base, with 3–6 secondary veins on the larger side, 3–5 secondary veins on the smaller side. Inflorescences 1–3 per stem, bisexual, axillary, erect, cymose, with up to 6 branches, bearing up to 16 staminate flowers and 16 pistillate flowers, protandrous; peduncle to 23 cm long, pale green to red, glabrous, bracts deciduous, ovate to oblong, 6–15 × 2.5–7 mm, opaque, white flushed pink, glabrous, apex acute, margin entire to serrulate at the apex, aciliate. Staminate flowers: pedicels to 17 mm long, glabrous; tepals 4, spreading, outer 2 broadly ovate, 6–17 × 6–16 mm, apex rounded, white flushed pink, glabrous, margin entire, aciliate, inner 2 elliptic, 4–11 × 1.5–3 mm, apex rounded, white, glabrous, margin entire, aciliate; stamens 30–40, spreading, orange, filaments 0.5–4 mm long, free, anthers obovoid, ca 0.3 × 0.2 mm, dehiscing via lateral slits, connectives extended to 0.1 mm, symmetrically basifixed. Pistillate flowers: pedicels to 30 mm long; bracteoles 0–2, positioned directly beneath the ovary, filamentous, 1–3 mm long, opaque, white to brown, glabrous, margin entire, aciliate; tepals 5, subequal, persistent in fruit, spreading, elliptic to ovate, 5–21 × 2–11 mm, apex rounded, white flushed pink, glabrous, margin entire to serrulate at the apex, aciliate; ovary body ellipsoid to ovoid, 7–14 × 3–7 mm, white flushed pink, glabrous, unequally 3-winged, wings semi-circular to triangular, largest 12–20 × 6–17 mm, smallest 10–20 × 3–13 mm; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow-orange, free, 1.5–9 mm long, once-divided, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 18 mm long. Fruit body ovoid, to 14 × 8 mm, drying brown, wings same shape as in ovary, the largest expanding to 20 × 17 mm, the smallest expanding to 20 × 13 mm.

Proposed conservation assessment

Assessed by Tebbitt et al. (2018a) as Least Concern (LC).

Identification notes

Begonia arrogans is most like B. wollnyi and the two species can be easily distinguished when with staminate flowers as B. wollnyi has 50–100 stamens and B. arrogans has 30–40. Distinguishing sterile material is more difficult. Begonia wollnyi tends to have more (5–8 vs 0–3) lobes to each leaf blade and those lobes are more deeply cut (to half the length of the leaf rather than a third). Interestingly, mature leaves of B. wollnyi tend to be more patterned and more iridescent than the first few leaves on the same plant, whereas the opposite is true in B. arrogans .

Distribution and ecology

Endemic to Peru and known from Ucayali, Pasco, and Junín Regions ( Fig. 65B ). Found in Amazonia and lower montane forest at an elevation of 550–1050 m a.s.l. Begonia arrogans has a succulent stem and drops its leaves in the dry season, which is usually from September to February. The species flowers at the start of the dry season, usually after the leaves have been dropped.

Figures

Fig. 65. Distribution of the acerifolia group of Begonia sect. Knesebeckia (Klotzsch) A.DC. in Peru and surrounding countries. A. B. acerifolia Kunth (red). B. B. arrogans Irmsch. (red) and B. ludwigii Irmsch. (blue). C. B. monadelpha (Ruiz ex Klotzsch) A.DC. (red) and B. serotina A.DC. (blue). D. B. huancabambae Moonlight sp. nov. (red) and B. wollnyi Herzog (blue). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 67. Begonia arrogans Irmsch. A. Habit with sun leaves. B. Shade leaf, adaxial surface. C. Stipule. D. Bract, adaxial surface. E. Staminate flower, front view. F. Smallest tepal of the staminate flower. G. Largest tepal of the staminate flower. H. Androecium, side view. I. Pistillate flower, side view. J. Pistillate flower, front view. K. Cross section of ovary. L. Smallest tepal of the pistillate flower. M. Largest tepal of the pistillate flower. N. Gynoecium, side view. All photographs taken by D.A. Purvis & P.W. Moonlight in the living collections of the Royal Botanic Garden Edinburgh (Accession 20160124, grown from seeds collected as part of P.W. Moonlight & A. Daza 239).