Begonia obtecticaulis Irmsch.
Creators: name: Moonlight, Peter. W.
name: Jara-Muñoz, Orlando A.
name: Purvis, David A.
name: Delves, Jay
name: Allen, Josh P.
name: Reynel, Carlos
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia obtecticaulis

description: 16. Begonia obtecticaulis Irmsch.
Figs 1D, 2C, 6E, 24D, 33
Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 74 (4): 600 (Irmscher 1949).
– Type: PERU – Huánuco Region • Yanano; [9°51′ S, 75°49′ W]; ca 1828 m a.s.l.; 13–16 May 1923; J.F. McBride 3721; holotype: F [V0360598F].
Brako & Zarucchi (1993: 194); León & Monsalve (2006: 167).
Etymology
The epithet derives from the Latin words ‘ obtectus ’ and ‘ caulis ’, meaning ‘hidden’ and ‘stem’. This refers to the large, persistent stipules that clasp the stem and hide it from view.
Selected specimens examined
PERU – San Martín Region: Prov. Huallaga • Valley of río Apisoncho, 30 km above Jucusbamba; 7°55′S, 77°10′ W; 2600 m a.s.l.; 25Aug. 1965; A.C. Hamilton & P.M. Holligan 1421; K, NY. – Huánuco Region: Prov. Marañón • route west of Uchiza; 8°36′29″ S, 76°40′42″ W; 1464 m a.s.l.; 9 Feb. 2016; P.W. Moonlight & A. Daza 208; E [E00885461], G, MO, MOL • ibid.; 8°38′43″ S, 76°48′55″ W; 2086 m a.s.l.; 9 Feb. 2016; P.W. Moonlight & A. Daza 212 (E [E00885463], MOL, P • Dist. Cholón, San Pedro de Chonta, retorno desde el campamento hacia el pueblo San Pedro de Chonta; 8°38′13.42″ S, 76°53′08.57″ W; 3200 m a.s.l.; 21 Jul. 2021; P. González & P. Arista 10016; USM.
Description
Caulescent herb, to 1.5 m high. Stem erect, branching; internodes to 9.5 cm long, to 8 mm thick, succulent, pale green to dark red, glabrous. Stipules in unequal pairs, persistent, lanceolate to broadly ovate, clasping the stem, 9–35 × 4–18 mm, apex acute, base cuneate, translucent, pale green to brown, glabrous, margin entire, aciliate. Leaves> 5, alternate, basifixed; petiole 0.8–4.5 cm long, pale green to red, glabrous; blade asymmetric, lanceolate to ovate, to 9 × 3.5 cm, succulent, apex acuminate, base transversely cordate, basal lobes rounded, sinus to 6 mm deep, margin irregularly double-dentate, ciliate, upper surface bright green, glabrous, lower surface pale grey-green, glabrous, veins palmate-pinnate, 4–6 veined from the base, with 2–4 secondary veins on the larger side, 1–3 secondary veins on the smaller side. Inflorescences 1–3 per stem, bisexual, axillary, erect, cymose, with 2 branches, bearing up to 4 staminate flowers and 8 pistillate flowers, protandrous; peduncle to 8 cm long, red, glabrous, bracts persistent, lanceolate, 7–10 × 2–3 mm, translucent, white, glabrous, apex acuminate, margin lacerate, ciliate. Staminate flowers: pedicels to 12 mm long, glabrous; tepals 2, spreading, broadly ovate, 12–14 × 12–15 mm, apex obtuse, white to pink, glabrous, margin entire, aciliate or rarely ciliate at the base; stamens 25–30, spreading, yellow, filaments 1.5–3 mm long, free, anthers ellipsoid, 1.5–2 × 0.75 mm, dehiscing via lateral slits, connectives extending to 0.4 mm, symmetrically basifixed. Pistillate flowers: pedicels to 8 mm long; bracteoles 2, lanceolate to ovate, ca 1 × 0.5 mm, translucent, white tinged pink; tepals 5, subequal, deciduous in fruit, spreading, elliptic to ovate, 7–15 × 4–6 mm, apex rounded to acute, white, glabrous, margin entire, aciliate; ovary body ovoid, ca 7 × 6 mm, white, glabrous, unequally 3-winged, wings triangular, largest ca 10 × 10 mm, smallest ca 10 × 3 mm; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow, free, ca 5 mm long, irregularly 2–5 times-divided, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 18 mm long. Fruit body ovoid, to 9 × 6 mm, drying brown, wings same shape as in ovary, the largest expanding 12 × 18 mm, the smallest expanding to 12 × 6 mm.
Proposed conservation assessment
Previously assessed by León & Monsalve (2006) as Endangered (EN); however, their concept of the species included specimens of B. albomaculata C.DC. Known from three populations, but the type locality has undergone severe deforestation in the last century and it was last collected there in 1923. Given its EOO of <5000 km 2, that is known from three populations, and its probable extirpation from the type locality, we assess B. obtecticaulis as Endangered (EN B1ab(iv)).
Notes
Description of the pistillate flowers made using living accession 20160137a at the Royal Botanic Garden Edinburgh.
Identification notes
Begonia obtecticaulis is one of three Peruvian caulescent begonias with large, persistent stipules that clasp the internodes and are longer than the internodes. This character is shared with B. inbrexiformis and B. serratistipula sp. nov. Begonia obtecticaulis can be distinguished from B. imbrexiformis sp. nov. by its palmate-pinnate (vs pinnate) leaf venation and from B. serratistipula sp. nov. by the entire margins to its stipules (vs lacerate in the bottom third).
Distribution and ecology
Endemic to Peru and known from San Martín and Huánuco Regions (Fig. 24D). Found in lower, middle, and upper montane forest at an elevation of 1400–3200 m a.s.l. The species has most frequently been collected on the margins of humid forests, particularly in areas of transition to drier Andean shrublands. There are only a few natural areas of dry shrubland in the Andes of San Martín and Huánuco Regions at the elevation favoured by B. obtecticaulis but some, such as Ongón District, remain poorly collected.
description: Published as part of Moonlight, Peter. W., Jara-Muñoz, Orlando A., Purvis, David A., Delves, Jay, Allen, Josh P. & Reynel, Carlos, 2023, The genus Begonia (Begoniaceae) in Peru, pp. 1-334 in European Journal of Taxonomy 881 on pages 92-94, DOI: 10.5852/ejt.2023.881.2175, http://zenodo.org/record/8178280