Begonia galea Moonlight & A.Fuentes

Moonlight, Peter & Fuentes, Alfredo F., 2022, AN UPDATED CHECKLIST AND KEY TO THE SPECIES OF BOLIVIAN BEGONIA, INCLUDING ONE NEW SPECIES, Edinburgh Journal of Botany 79 (407), pp. 1-66 : 18-21

2.14. Begonia galea Moonlight & A.Fuentes , sp. nov.

Begonia galea is unique among South American Begonia as the only species whose inflorescence is a scorpioid cyme with a terminal pistillate flower.

– Type: Bolivia, La Paz Department, Prov. Franz Tamayo , Santo Domingo, arroyo San Pedro , 14°47′53′′S, 68°36′01′′W, 1414 m, 20 x 2006, A.F. Fuentes, M. Cornejo, E. Ticona, S. Sompero & C. Cuqui 11158 (holotype E [ E01004032 ]; isotypes BOLV, LPB, MO [MO-2080523], NOLS, US [ US00966728 ]). Figure .

Caulescent herb, lacking a tuber or rhizome, sometimes rooting from the lower nodes, terrestrial or epiphytic on the base of tree trunks. Stem erect, 20–60 cm tall, 1.5–3 mm in diameter, unbranched or branching at the base, internodes 8–60 mm, glabrous, light green flushed red around the nodes. Stipules tardily deciduous, lanceolate, 3.5–9 × 1–3 mm, apex acuminate, aristate, glabrous, light green, margin entire, aciliate. Leaves alternate, basifixed; petioles joining blade at a slight angle, 4–15 mm long, glabrous; blades asymmetrical, elliptic to oblanceolate, (30–)45–85(–115) × 10–30 mm, apex acuminate, base oblique, cordate on the broader side, basal lobe to 3 mm, overlapping the petiole, cuneate on the narrower side, venation pinnate, with 3–6 secondary veins on the broader side, 2–4 secondary veins on the narrower side, upper surface dark green, very sparsely pilose, lower surface green, glabrous, margin irregularly dentate, ciliate. Inflorescences few, axillary, erect, arising close to the apex of the stem, a helicoid monochasial cyme, protandrous, c.4 staminate flowers developing before a terminal, pistillate flower; peduncle 18–55 mm long, glabrous, white flushed pink; pedicels of staminate flowers held vertically, sequentially shorter along the inflorescence with basal most flower held above the subsequent flowers in sequence, the basal-most pedicel to 12 mm long, apical pedicel to 4 mm long, glabrous, white flushed pink; pedicels of pistillate flowers 8–10 mm long, glabrous, white flushed pink; bracts tardily deciduous, elliptic to ovate, 2–6 × 1–5 mm, apex acute to rounded, white, margin entire to lacerate, glabrous. Staminate flowers: tepals 2, held horizontally, ovate, 8–10 × 4–6 mm, apex acute, margin entire, glabrous, white with a pink flush on outer surfaces; stamens 8–10, fused at the base, held spreading horizontally, filaments 1.5–2 mm long, anthers symmetrically basifixed, oblong, 1–1.5 mm long, dehiscing via lateral slits, connectives extended to 1 mm.

Pistillate flowers: bracteoles 3, tardily deciduous, ovate, 3–4 × 3 mm, apex obtuse, white, glabrous, margin lacerate, ciliate; tepals deciduous in fruit, 5, spreading, elliptic, 7–9 × 2–3.5 mm, apex acute, margin entire, glabrous, white with a pink flush on outer surfaces, loosely reticulate at the apex; ovary body ovoid, the base truncate, c.4 × 3 mm, glabrous, 3-winged, wings white flushed pink, the upper wing longer than the other two, semicircular, front edge truncate, apex acute, lower edge rounded, 10–12 × 7–13 mm, the lower two wings triangular to oblong, front edge truncate, apex obtuse, lower edge gently rounded to truncate 6–8 × 5–6 mm, 3-locular, placentas bifid, bearing ovules on both surfaces; styles 3, yellow, free at base, c. 5 mm long, bifid from around a third of their length, stigmatic papillae in a twice spirally-twisted band. Fruiting pedicel to 1 cm long; fruit nutant, the base truncate, 6–9 × 2–4 mm, light brown, glabrous, wings same shape as in female flower, light brown, longest wing expanding to 10–12 × 12–13 mm, shorter two wings expanding to 6–8 × 5–6 mm.

Distribution and ecology. Begonia galea is known from six collections within 38 km of each other within the Franz Tamayo and Bautista Saavedra Provinces of La Paz Department, Bolivia. This species has been collected from 1250 to 1500 m within humid valleys in lower montane rain forest dominated by the palm Dictyocaryum lamarckianum H.Wendl. Begonia galea has been collected flowering and fruiting in October.

Etymology. The epithet galea is a Latin term referring to the helmets of Roman soldiers and gladiators; it emphasises the rounded appearance of the species’ fruits.

Proposed IUCN conservation category. The known extent of occurrence (EOO) of Begonia galea is 53 km 2, which is sufficiently small for it to qualify as Critically Endangered (CR) under IUCN criteria ( IUCN Standards and Petitions Subcommittee, 2019). Although its range falls partially in the Apolobamba protected area, these populations may be in decline due to intense human pressure ( Jones et al., 2018) from deforestation for agriculture (mainly coca plantations), gold mining and livestock ( Romero-Muñoz et al., 2019). The same does not apply to the populations of Santo Domingo, an area currently unaffected by deforestation or major development projects that could threaten their conservation in the short term. However, considering the potential for gold mining in this entire region and the intensive mining activities in surrounding areas ( Revollo & Campanini, 2014), it is possible that in the future these activities will expand and compromise the conservation of this species. We categorise Begonia galea as Near Threatened (NT) under IUCN criteria ( IUCN Standards and Petitions Subcommittee, 2019) because most of its range remains intact and we have no evidence for any decline in its population.

Additional specimens examined. BOLIVIA. La Paz Department. Franz Tamayo Province: Región Madidi, Santo Domingo, sector Lechemayu, en la Parcela Permanente 49. 14°46′09′′S, 68°37′11′′W, 1475 m, 19 viii 2010, A.F. Fuentes, P. Miranda, C. Miranda, L. Vaquiata & E. Segales 17037 ( LPB); Santo Domingo, sector Tintaya , parcela temporal 2, 14°47′09′′S, 68°35′00′′W, 1463 m, 13 x 2006, A.F. Fuentes, M. Cornejo, E. Ticona, S. Sompero & C. Cuqui 10998 ( LPB, MO [MO-2080525]) ; Región Madidi, Santo Domingo , sector arroyo Tintaya , 14°47′43′′S, 68°36′06′′W, 1400 m, 10 x 2006, L. Cayola, G. Chive, I. Loza, N. Chapi & P. JØrgensen 2471 ( LPB, MO [MO-2080524]) ; Región Madidi, Santo Domingo , sector arroyo Tintaya , 14°46′45′′S, 68°35′30′′W, 1468 m, 22 x 2006, L. Cayola, G. Chive, I. Loza, M. Cornejo, E. Ticona & A. Fuentes 2513 ( LPB, MO [MO-2143708], LPB, US [US00966727]) . Bautista Saavedra Province: Area Natural de Manejo Integrado Apolobamba , Tolapampa , por la carretera Charazani-Apolo, sector loma Callawaya, parcela permanente 2, 15°04′32′′S, 68°28′01′′W, 1250 m, 10 iv 2010, A.F. Fuentes, A. Escalante, R. Ticona & S. Quispe 15831 ( LPB, MO [ MO-2773642 ]) .

Notes. Begonia galea is unique among Andean Begonia in the structure of its inflorescence, a monochasial, scorpioid cyme that terminates in a pistillate flower. This structure is superficially reminiscent of the asymmetrical, thyrsoid inflorescences found in Begonia sect. Pilderia (Klotzsch) A.DC. (see Moonlight & Jara-Muñoz, 2017). However, the inflorescence of Begonia galea differs in that it is apical rather than terminal, and only has a single pistillate flower at the apex. Begonia galea also lacks the characteristic glandular hairs found in all members of Begonia sect. Pilderia . We consider the inflorescence of Begonia galea more likely to be a reduced form of the typical dichasial cyme found in most non-tuberous Andean species of Begonia , including Begonia sects. Cyathocnemis, Hydristyles and Ruizopavonia.

The sectional placement of Begonia galea is difficult because the species has a unique inflorescence structure and otherwise falls between Begonia sects. Cyathocnemis and Ruizopavonia. These two sections have very similar flowers and fruits and differ primarily in their leaves, which are straight with pinnate venation in Begonia sect. Ruizopavonia and transverse with palmate-pinnate venation in Begonia sect. Cyathocnemis . The leaves of Begonia galea are straight but have many fewer secondary veins than all Andean members of Begonia sect. Ruizopavonia . We suspect that Begonia galea is a member of Begonia sect. Cyathocnemis with straight leaves, similar to B. obtecticaulis Irmsch. ( Moonlight et al., 2018). The three bracteoles of Begonia galea positioned directly beneath the ovary are consistent with this hypothesis, because this character state is frequent in Begonia sect. Cyathocnemis whereas members of Begonia sect. Ruizopavonia have two bracteoles that are usually spaced out from the base of the ovary. We therefore tentatively place Begonia galea in Begonia sect. Cyathocnemis .

Identification notes. When the plant is fertile, it is easy to identify Begonia galea because of its unique inflorescence structure, which resembles the characteristic scorpioid cyme of members of the Boraginaceae . Sterile individuals may be confused with several species of Bolivian Begonia . The distichous, straight leaves of this species most resemble those of the Bolivian species of Begonia sect. Ruizopavonia , but unlike most Bolivian species in this section, Begonia galea is entirely glabrous. Begonia peruviana A.DC. is an often glabrous, Bolivian member of Begonia sect. Ruizopavonia and can be distinguished by its much more numerous and prominent secondary veins ( B. peruviana has 8–12 veins on the broader side of the leaf lamina vs 3–6 in B. galea). Finally, Begonia galea could be confused with either B. comata Kuntze or B. oblanceolata Rusby but has smaller (<1 cm long), tardily deciduous stipules that do not clasp the stem and leaves, with an irregularly serrate margin (vs persistent stipules,> 1 cm long, that clasp the stem and leaves, with a denticulate or crenulate margin).