Begonia chucantiensis Guillén, Moonlight & Jara, 2025

Guillén, Lucila, Moonlight, Peter W., Jara-Muñoz, Orlando A., de Stapf, María Sánchez & Carrión, Juan F., 2025, A new species of Begonia (Begoniaceae) from the eastern mountains of Panama, PhytoKeys 256, pp. 61-71 : 61-71

Begonia chucantiensis Guillén, Moonlight & Jara sp. nov.

Figs 1 , 2

Diagnosis.

Within Begonia section Lepsia , B. chucantiensis resembles B. confinis in having persistent stipules and two flowers per inflorescence; however, it differs by having glabrous young branches and uniform nodes (vs. ferruginous indumentum and swollen nodes), stipules 8.5–10.5 × 3.5–4.5 mm (vs. 0.8–1.3 × 0.3–0.4 mm), elliptic to lanceolate leaf blades (vs. rhomboid subtrilobed), 3.3–6 × 0.8–1.7 cm leaf blades (vs. 0.6–1.3 × 0.3–0.6 cm), peduncles up to 1.3 cm (vs. 2.8 cm), 12–14 stamens (vs. 8–10), and fruits with similar wing shape and size (vs. one wing conspicuously unequal).

Type.

Panama • Darién: Distrito de Santa Fé. Reserva Natural Privada Cerro Chucantí ; 8°47'54"N, 78°27'46"W, 1297 m a. s. l., 27 Mar 2023 (♂ fl., ♀ fl., and fr.), Mitre-Ramos, C., Camaño, J., Ortega, J. & Ortega, B. 8 (holotype: PMA 132927 ! [isotypes will be sent to the following herbaria: COL, K, MO]) .

Description.

Perennial, terrestrial, erect herb up to 2 m tall. Main stem green, succulent, glabrous, branched; branches slender, lenticels absent, internodes glabrous, 0.5–4 cm long and 1.2–3.5 mm in diameter, nodes not swollen. Stipules persistent, pink to brown, oblong to ovate, 8.5–10.5 × 3.5–4.5 mm, slightly asymmetric, glabrous, membranous, hyaline, margin entire, apex obtuse, with a central vein and an apical seta. Leaves more than 5 per stem; petioles green, 0.5–1.5 mm × 0.3–0.7 mm, terete, glabrous; leaf blade elliptic to lanceolate, 3.3–6 × 0.8–1.7 cm, discolorous, lustrous green adaxially, paler green abaxially, with slightly pinkish veins and margin, base slightly asymmetric, apex acuminate, margin dentate, each dent with a hydathode and often an additional hydathode between the dents, dent triangular, 0.6 × 0.3 mm; venation pinnate, 5–8 veins per side. Inflorescences bisexual, axillary, cymose, 2 - flowered, protandrous, subtended by a persistent, dissected bract, 7–8 × 6–7 mm, margin serrate; peduncle up to 1.3 cm long. Staminate flowers: pedicel up to 1.2 cm long; tepals 4, white, glabrous, margin entire, apex rounded, outer 2 ovate, 10–12 × 7–9 mm, apex rounded, inner 2 oblanceolate, 7–9 × 4–5 mm; stamens 12–14, yellow, filaments 0.5–1 mm long, free, anthers ellipsoid, 2.7–3.3 × 0.8–1 mm, dehiscence by lateral slits, connective 0.9–1 × 0.7–0.9 mm, basifixed. Pistillate flowers: pedicel up to 4 mm long, bracteoles 2, persistent, positioned directly below the ovary, ovate, 5–7 × 3.5–4.5 mm, auriculate, margin dentate; tepals 5 or 6, unequal, deciduous in fruit, ovate, 9–14 × 4–9 mm, white, glabrous, margin entire; ovary body ovoid, 6–8 × 3–4 mm, whitish, translucent, glabrous, 3 - winged, wings nearly equal in size, 6–8 × 2.5–3.5 mm, margin serrate; 3 - locular, placentas bifid and bearing ovules on both surfaces; styles 3, yellow, united at base in a 0.8–1.2 mm long column; arms 1–2 mm long, once divided; stigmatic papillae in a spirally twisted band. Fruits: pedicels up to 2 cm long; body ovoid, up to 10 × 4 mm, drying brown, wings expanding up to 12 × 7 mm. Seeds 0.3–0.5 × 0.1–0.2 mm, ellipsoid.

Distribution.

Begonia chucantiensis is only known from the type locality, Cerro Chucantí (Serranía de Majé), in eastern Panama (Fig. 3 ).

Habitat and ecology.

The species grows in the understory, on steep slopes, beneath 20–30 m tall trees, in premontane rainforest, at an elevation of 1200–1300 m above sea level. It has been recorded with flowers and fruits in January and March.

Etymology.

The specific epithet refers to the locality where the new species is known: Cerro Chucantí.

Preliminary conservation status.

Begonia chucantiensis is currently known from only two localities that we consider to be one location (Area of Occupancy [AOO] of approximately 4 km 2) within the Cerro Chucantí Private Natural Reserve. Although confined to a private reserve, B. chucantiensis faces significant threats. Long-term protection is not assured, and any adverse event, including extreme weather, could lead to the loss of the entire population. Furthermore, deforestation and agricultural expansion pose substantial risks in the surrounding areas, resulting in a projected decline in both habitat quality and AOO (<10 Km 2). Consequently, following the IUCN Red List Categories and Criteria ( IUCN 2024 ), this species is preliminarily classified as Critically Endangered (CR B 2 ab (iii )).

Additional specimen examined

(paratype). Panama • Darién: Distrito de Santa Fé. Serranía de Majé. Corregimiento de Río Congo. Reserva Natural Privada Cerro Chucantí, laderas de Cerro Chucantí, cercano al campamento del filo , 8°48'16"N, 78°27'34"W, 1300 m a. s. l., 27 Jan 2023 (♂ fl., ♀ fl., and fr.), Guillén, L., Guerra, J. L., Lino, M. & Fatacioli, G. 783 ( PMA!) .

Discussion.

Following the taxonomic key for Begonia in the Flora Mesoamericana ( Burt-Utley 2015), the new species would be placed in couplet 23, which separates B. liesneri Burt-Utley & Utley and B. semiovata Liebm. Both species share some characters with B. chucantiensis , including: the habit of an erect to somewhat sprawling subshrub; apparently non-rooting stems at the nodes; persistent to lately deciduous stipules; glabrous to very sparsely pilose or villous and pinnately veined glabrous blades; well-developed, persistent bracteoles and sub-equal ovary / fruit wings. The new species shares with B. liesneri the subshrubby habit and staminate flowers with tepals greater than 7 mm long. B. semiovata , on the other hand, is an herbaceous species with staminate flowers with tepals up to 3 mm long. On the other hand, B. semiovata presents leaves with a similar number of veins per side (7–9) as B. chucantiensis (5–8), while B. liesneri has more veins per side (( 10) 12–15).

Supplement to the key to Begonia in Flora Mesoamericana ( Burt-Utley 2015)

Note that couplet 23 has been modified, and a new couplet, 23 ’, has been inserted, with characters to differentiate B. liesneri from B. chucantiensis .

In Begonia section Lepsia , where we place the new species, 8 species are currently recognized: B. barrigae L. B. Sm. & B. G. Schub. , B. confinis L. B. Sm. & Wassh. , B. foliosa Kunth , B. guaduensis Kunth , B. holtonis A. DC. , B. meridensis A. DC. , B. opuliflora Putz and B. praerupta Irmsch ( Moonlight et al. 2023) . However, B. chucantiensis is readily distinguished from most other members of the Lepsia section by its 2 - flowered inflorescences. While most species within the section possess multifloral inflorescences with more than 12 flowers, only B. confinis shares this bifloral characteristic. Nevertheless, B. chucantiensis can be differentiated from B. confinis by the characteristics mentioned in the diagnosis. Furthermore, B. confinis is geographically restricted to the Serranía del Perijá, the northernmost extension of the Andes mountain range along the Colombia-Venezuela border (Fig. 3 ), while B. chucantiensis is found over 600 km away on Cerro Chucantí in the Serranía de Majé, eastern Panama.

The new species shares some similarities with the Brazilian Begonia itatinensis Irmsch. ex Brade ( Begonia sect. Pritzelia (Klotzsch) A. DC. ), including persistent stipules, small, slightly asymmetric leaves with pinnate venation, 2 - flowered inflorescences, and 8–10 stamens. However, species in section Pritzelia have cystoliths in the leaf epidermal cells ( Moonlight et al. 2018), which are absent in this new species. Additionally, B. itatinensis has a scandent, pubescent stem ( Smith and Smith 1971; Jaramillo 2017) and entire placentas ( Brade 1944; Mamede et al. 2012), while B. chucantiensis has an erect, glabrous stem and bifid placentas.

Figures

Figure 1. Holotype of Begonia chucantiensis sp. nov. (PMA 132927).

Figure 2. Morphological aspects of Begonia chucantiensis sp. nov. A plant habit B fertile branches C detail of fertile branch D leaves viewed from the adaxial side and staminate flower E leaves viewed from the abaxial side, staminate flower and fruit F stipules G front view of staminate flower H pistillate flower I lateral view of the fruit. Images A, B, D, E C. Mitre-Ramos. C, F, I L. Guillén. G, H J. L. Guerra.

Figure 3. Geographical distribution of Begonia chucantiensis sp. nov. (red circle) in relation to its most morphologically similar relative, B. confinis (black circles).