Begonia unduavensis Rusby

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 : 37-38

5.28. Begonia unduavensis Rusby , Descr. S. Amer. Pl. 64 (1920). –

Type: Bolivia, [La Paz Department, Prov. Sud Yungas], Unduavi, [16°19′S, 67°54′W], 8000 ft, x 1885, H.H. Rusby 677 (lectotype NY [ NY00118708 ] designated in: Revista Univ. (Cuzco) 33(87): 80 (1944) by Smith, L.B. & Schubert, B.G .; isolectotypes F [ F0052644 F], GH [ GH00068294 ], NY [ NY01477261 ], US [ US00115484 ] ).

L.B. Smith & B.G. Schubert, Revista Univ. (Cuzco) 33(87): 80 (1944); R.C. Foster, Contr. Gray Herb. 184: 137 (1958); D.C. Wasshausen et al. in P.M. JØrgensen et al. (eds), Cat. Bolivia, Monogr. Syst. Bot. Missouri Bot. Gard. 129: 386 (2013).

Begonia lignosa Rusby , Descr. S. Amer. Pl. 65 (1920). – Type: Bolivia, [La Paz Department], Prov. Sud Yungas, Unduavi, [16 ° 19′S, 67 ° 54′W], 3100 m, xi 1910, O. Buchtien 2899 (lectotype NY [ NY00118625 ] designated here, first stage designated in: Revista Univ. (Cuzco) 33(87): 81 (1944) by Smith, L.B. & Schubert, B.G.; isolectotypes NY [ NY01477266 ], US [2: US00115367 , US00074725 ] ).

R.C. Foster, Contr. Gray Herb. 184: 137 (1958).

Begonia obtecticaulis auct. non. Irmsch., D.C. Wasshausen et al . in P.M. JØrgensen et al. (eds), Cat. Bolivia, Monogr. Syst. Bot. Missouri Bot. Gard. 129: 385 (2013).

Caulescent herb, lacking a tuber or rhizome. Stem erect, to 50 cm tall, 1.5–4 mm in diameter, branching, internodes (5–) 25–50 mm, glabrous to sparsely pilose, red. Stipules persistent, triangular, 7–18 × 2–4 mm, apex acuminate, mucronate, glabrous, light brown, margin entire, aciliate. Leaves alternate, basifixed; petioles joining blade at almost a right angle, 5–28 mm long, glabrous to sparsely pilose; blades asymmetrical, transversely deltoid, 30–95 × 15–35 mm, apex acuminate, base cuneate on the narrow side of the blade, auriculate on the broad side of the blade, venation palmate-pinnate, 4 or 5 veins from the base, 3 or 4 veins on the broad side of the blade, 2 or 3 on the narrow side, upper surface dark green, sometimes with a red line around the margin, sparsely pilose, lower surface pale green to red, sparsely pilose, margin double-dentate, ciliate. Inflorescences 1–3 per stem, axillary, erect, arising close to the apex of the stem, a dichasial cyme, protandrous, with up to 16 staminate flowers and 8 pistillate flowers; peduncle 22–33 mm long, glabrous, red; pedicels of staminate flowers 5–22 mm long, glabrous, red; pedicels of pistillate flowers 7–16 mm long, glabrous, red; bracts persistent, elliptic to lanceolate, 4–7 × 1–3 mm, apex obtuse to acute, red to brown, glabrous, margin lacerate, ciliate. Staminate flowers: tepals 2, spreading, white to pink, orbicular, 6–14 × 7–14 mm, apex rounded, base rounded, margin entire, glabrous; stamens c.75, fused at the base, spreading, filaments 1.5–2 mm long, anthers symmetrically basifixed, oblong, 1.2–1.5 mm long, dehiscing via lateral slits, connectives extended 0.3–0.5 mm. Pistillate flowers: bracteoles lacking; tepals deciduous in fruit, 5, spreading, elliptic to ovate, 9–14 × 3–6 mm, apex rounded, margin entire, aciliate, glabrous, white to pink; ovary body ovoid, 4.5–5 × 3.5–4 mm, pink, 3-winged, wings pink, one wing longer than the other two, rectangular, ascending, front edge truncate, apex truncate, lower edge slightly rounded, 6–9 × 7–13 mm, the shorter two wings semicircular to triangular, front edge truncate, apex rounded, lower edge gently curved, 4.5–5 × 1–2 mm, 3-locular, placentas bifid, bearing ovules on both surfaces; styles 3, yellow, free at base, irregularly multifid from around half their length, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 3.2 cm long; fruit held erect, body ovoid, 9.5–12.5 × 7.5–12 mm, light brown, glabrous, wings same shape as in pistillate flower, light brown, longest wing expanding to 17 × 30 mm, shorter two wings expanding to 10.5 × 3 mm.

Distribution. Endemic to Bolivia.

Nomenclatural notes. The name Begonia unduavensis Rusby was published based on the collection H.H. Rusby 677, but no herbaria were cited. Rusby’s protologue cited material collected at an elevation of 8000 ft, and the known sheets of this material state either 8000 ft or 12,000 ft. The two sheets that state 8000 ft are one in the New York Botanical Garden herbarium ( NY00118708 ) and one in the Field Museum in Chicago ( F0052644 F). Smith & Schubert (1944a) cited the type of Begonia unduavensis in the New York Botanical Garden herbarium, which is an effective lectotypification. We cite as syntypes all sheets that were collected at 12,000 ft.

The protologue of Begonia lignosa Rusby cited the collection O. Buchtien 2899, but no herbarium ( Rusby, 1920). Smith & Schubert (1944a) cited material in the New York Botanical Garden herbarium as the type, which counts as an effective lectotypification because there are two matching sheets in New York. We select the duplicate NY00118625 as the lectotype, because it has both flowers and fruits.

Identification notes. Begonia unduavensis is most similar to B. unilateralis Rusby , with both species having relatively small (<8 cm long), obliquely lanceolate to ovate leaves that are truncate at the base. They are best distinguished by their indumentum. Begonia unduavensis has stems, petioles and leaf laminae that are sparsely to densely pilose, whereas B. unilateralis has an indumentum of peltate scales. This indumentum is densest on the stems, petioles, and veins on the leaf lower surface (although it can rub off); moderately dense on the lower leaf surface; and sparse on the upper leaf surface.