Begonia jenmanii Tutin 1940
Creators: name: Moonlight, P. W.
name: Jara-Muñoz, A.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Cucurbitales
Begoniaceae
Begonia
Begonia jenmanii

description: 4. Begonia jenmanii Tutin (Fig. 7d)   
 J. Bot., 78: 252 (1940). Type: GUYANA. Kaieteur Fall, wet boulders in the spray of the fall in the gorge, 21 August 1933, alt. ca. 300ft., T.G. Tutin 529 (holotype BM [BM001006460]).   
 Plants caulescent, rhizomatous herbs, 15–100 cm high; stem repent, rooting at the nodes, flexuous, unbranched; internodes to 1.5 cm long and rhizomatous at the base of the stem, to 5 cm long and trailing towards the apex, to 1 cm thick, woody, red, sparsely to densely villous towards the apex, hairs ca. 2mm long, red; stipules persistent, ovate, 6–10 × 5–6 mm, apex acute, margins entire, aciliate. Leaves alternate, clustered towards the apex of the stem, 5 or fewer, basifixed; petioles 7–15 cm long, densely villous, hairs ca. 2mm long, red; lamina asymmetric, transverse, ovate, 7–20 × 4.5–12.5 cm, the apex abruptly acuminate, base cordate, lobes not overlapping to overlapping, sinus to 2.5 cm deep, acuspidate, margins entire to dentate, teeth 0.2–0.5 mm long, densely red-ciliate, the upper surface even, green, with sparsely to moderately-densely villous between the tertiary veins, very dense towards the margins of the lamina, the veins glabrous to densely villous towards the petiolar insertion, the lower surface even, red, sparsely to densely glandular-pilose between the tertiary veins, very dense towards the margins of the lamina, the veins densely villous to very-densely villous towards the petiolar insertion; venation palmate-pinnate, with 6–7 veins from the base, with 6–8 lateral veins on the widest side of the lamina, and 4–6 lateral veins on the narrow side. Inflorescences: axillary, terminal, erect, to 50 cm, glabrous throughout, thrysoid with ca. 15 lateral branches, basal-most lateral branch thyrsoid with ca. 10 lateral branches, lateral branches cymose, branching to 3 to 5 times, protandrous; peduncle to 37 cm long, internodes to 11 cm long, decreasing to ca. 5mm long at the apex, peduncles of cymes 2–20 mm, secondary to quinary branches 1–4 mm; bracts deciduous, bracts of thyrsoid lateral branches like the leaves, the remainder narrowly-elliptic, 0.5–4 × 0.2–2 mm, membranous, glabrous, apex acute, pink, margins entire, aciliate; pedicels of male flowers 2–8 mm long, fibrous; pedicels of female flowers 2–10 mm long, fibrous. Male flowers: tepals 4, membranous, glabrous, margins entire, aciliate, the outer ovate, 3–7 × 1.5–4 mm, pink to red, apex acute to obtuse, the inner elliptic, 2–3 × 0.5–1 mm, white to pink, apex acute; stamens ca. 15, united along the length of a ca. 1–2 mm long column, yellow; filaments <0.5 mm, anthers broadly-oblong, 0.4 × 0.6 mm, obtuse, dehiscing through lateral slits, the connective not projecting. Female flowers: bracteoles 2, white to red, deciduous, lanceolate to ovate, 2–5 × 0.5–4 mm, membranous, glabrous, apex rounded, margins entire; tepals 5, deciduous in fruit, same colour as males, subequal, lanceolate to ovate, 3–4 × 1–4 mm, margins entire, acilate; ovary body globose, 4–6 × 4–5 mm, glabrous, red, 3-locular, unequally 3-winged, the wings glabrous, largest wing triangular, not ascending, 6–15 × 8–9 mm, apex acute, base cordate to rounded, margins entire, acilate; the smallest 2 triangular, not-ascending, 2–4 × 8–9 mm, apex acute, base rounded, margins entire, acilate; placentae axile, bilamellate, ovuliferous all over; styles 3, ca. 2 mm long, bifid 1 mm from base, the branches erect, spirally twisted two times, yellow, tardily-deciduous in fruit. Fruiting pedicel elongating to 20 mm, fibrous. Fruit ellipsoid, to enlarging to 8 × 6 mm, wings same shape as in ovary, the largest enlarging to 10 × 20 mm, the smallest enlarging to 8 × 8 mm. Seeds globose, 0.2 × 0.2 mm.   
 Distribution and habitat:— Guyana. Begonia jenmanii is known only from the Potaro River around the Kaieteur Falls and the Cerro Ayanganna on the border between the Potaro-Siparuni and Cuyuni-Mazaruni regions of Guyana. The latter locality is> 20 km from the border with the Roraima State of Brazil and> 100 km from the border with the Bolívar state of Venezuela. The environment appears suitable for B. jenmanii for ca. 15 km over each border before changing to savanna. It seems likely B. jenmanii also occurs in these areas.   
 Taxonomic comments:— Begonia jenmanii was only doubtfully included in B. sect. Pilderia by Doorenbos et al., who were misled by the species’ supposed lack of bracteoles, undescribed placentae, and transverse, palmate-pinnately veined leaves. However, transverse, palmate-pinnately veined leaves are shared with B. glandulifera and B. humillima; B. jenmanii does possess bracteoles (although they are early-deciduous); and its placentae match those of the B. glandulifera and B. mariannensis.   
 IUCN Redlist Assessment:— Begonia jenmanii is locally common throughout its range, the majority of which falls within the Kaiteur National Park. Although the species has an EOO of> 1500 km 2 and an AOO of ca. 50 km 2, no information is available about population trends within this species. We assess B. jenmanii as Least Concern (LC).   
 Additional specimens examined:— GUYANA: Potaro-Siparuni: Lower slope of Mount Wekemung, 5˚5’ N, 58˚50’ W, alt. 1070–1300m, 1 July 1989, B. M. Book & G. J. Samuels 9019 (NY [NY02497237]); Potaro Dist., Kahaima Mt., ca. 1000 ft., 17 August 1959, B. A. Whitton 100 (K); Cuyuni-Mazaruni, Pakaraima Mts., ascent and transect 4 km along NE plateau of Mt.Ayanganna, 5˚24’ N, 59˚57’ W, alt. 1100–1500 m, 6 November 1992, T. W. Henkel & B. Hoffman 152 (US [US 00777547]); Mt. Ayanganna, east face, base of first three escarpments, 5˚20’4” N, 59˚55’30” W, alt. 712 m, 9 June 2001, H. D. Clarke et al. 8969 (US [US 00812717]; NY [NY02497233]); Mt. Ayanganna, east fase, camp at base of second of four escarpments, alt. 1120m, 16 June 2001, H. D. Clark et al. 9253 (NY [NY02497234]); Mt. Ayanganna, alt. 1000–1500m, 5–6 February 1955, B. Maguire et al. 40592 (NY [NY02497230]), ibid. B. Maguire et al. 40593 (NY [NY02497231]); Upper Potaro R., 2km south of camp, along stream (affluent of Potaro R.), 5˚18’5” N, 59˚54’40” W, alt. 650m, 3 June 2001, H. D. Clarke et al. 8919 (K, U [U0184055], US [US 00800188]; NY [NY02497232]); Line from Kaieteur to Tukeit, 5˚13’ N, 59˚27’ W, alt. 90 to 450 m, 19 July 1991, K. Lance & A. Petersen A 46 (U, US [US 00742264]); Along Potaro River between Kaieteur Falls and Tukeit, 4 km downstream, 5˚12’ N, 59˚28’ W, alt. 130 m, 11 October 1987, L. P. Kvist et al.189 (U [U0103013], US [US 00457054], US [US 00742279], NY [NY02497238]); Forest along trail from Kaieteur Falls to Tukeit, alt. 1300–1700 ft, 2 March 1962, R. S. Cowan & T. R. Soderstrom 2018 (K, US [US 00062932], NY [NY02497227]); Potaro River Gorge, trail from Tukeit to Kaieteur, 28 April 1944, B. Maguire & D. B. Fanshawe 23081 (K, P [P05587688], NY [NY02497228]); Potaro River, dark rocky forest in gorge below Kaieteur Falls, 10 September 1937, N. Y. Sandwith 1475 (K); Kaieteur National Park, Kaieteur gorge, W bank Potaro R, 2.5 km from falls, 5˚12’ N, 59˚28’ W, alt. 100–170 m, 15 July 1993, T. W. Henkel & R. Williams 2222 (NY [NY02497240], US [US 00518132]); Below the Kaiteur, Potaro River, on rocks under the fall, September–October 1881, G. S. Jenman 891 (paratype K [K000536716]); Kaieteur Fall, wet bounders in spray from the fall, alt. ca. 300ft., 21 August 1933, T. G. Tutin 530 (paratype BM, K [K000536717]); Kaieteur Falls, 18 May 1944, B. Maguire & D. B. Fanshawe 23530 (NY [NY02497229]); Kaieteur Falls, 1872, C. Appum s.n. (BM); Under rocks in the Kaietur ravine, November 1875, E. F.i. Thurn s.n. (paratype K); Above Tukeit, Potaro River, 23 February 1879, E. F.i. Thurn s.n. (paratype K [K000536715]); Kaieteur Falls National Park, 5˚12’ N, 59˚29’ W, alt. 500 m, 2 April 1988, W. Hahn et al. 4151 (US [US 00427593]); Kaieteur Plateau, Trail from Kaieteur Falls to Tukeit, alt. 1300–1700m, R. S. Cowan & T. R. Soderstrom 2018 (NY); Kaieteur National Park, trail to Tukeit as trail begins descent into ravine, before first bridge, 5˚10’ N, 59˚29’ W, alt. 300 m, 13 June 1994, C. L. Kelloff et al. 1068 (K, U [U0038683], US [US 00457054]. US [US 00587867], NY [NY02497235]); Kaieteur Falls National Park, 5˚10’ N, 59˚29’ W, alt. 500m, 16 April 1988, W. H. Hahn et al. 4628 (P [P05494668], NY [NY02497239], US [US 00427585]); Mt. Wokomung, camp at base of first four escarpments, 5˚7’47.8” N, 59˚48’35.5” W, alt. 674 m, 24 June 2003, H. D. Clarke et al. 10064 (US [US 00942951]); Mt. Wokomung, NE facing slope of first four escarpments, 5˚7’38.1” N, 59˚48.40.1” W, alt. 790 m, 25 June 2003, H. D. Clarke et al. 10160 (US [US 00973888], NY [NY02497235]); Pakaraima Mtns; upper Ireng watershed, Sukabi River, adjacent forests and base of Andu Falls, 5˚6’ N, 59˚58’ W, alt. 625 m, 19 October 1994, P. Mutschnick et al. 113 (NY [NY02497241], US [US 00587637]); Pakaraima Mts, Mt. Wokomung, Suruwabaru Creek, 2–3 km upstream from junction with Yuarka River, 05˚3’ N, 59˚54’ W, alt. 675–750m, T. W. Henkel et al. 1253 (US [US 00518720]); Upper Mazaruni River Basin, Havea-Buba, palm forest along base, NE side, alt. 800m, 27 July 1960, S. S. Tillett et al. 44939 (K [2], MO [MO-1642447], NY [NY02497226]).
description: Published as part of Moonlight, P. W. & Jara-Muñoz, A., 2017, A revision and recircumscription of Begonia Section Pilderia including one new species, pp. 1-22 in Phytotaxa 307 (1) on pages 14-15, DOI: 10.11646/phytotaxa.307.1.1, http://zenodo.org/record/13690119