Begonia pastoensis var. pastoensis A.DC.

Moonlight, Peter. W., Jara-Muñoz, Orlando A., Purvis, David A., Delves, Jay, Allen, Josh P. & Reynel, Carlos, 2023, The genus Begonia (Begoniaceae) in Peru, European Journal of Taxonomy 881, pp. 1-334 : 31-34

1. Begonia pastoensis var. pastoensis A.DC.

Figs 13A , 14

Annales des Sciences Naturelles Botanique, Série 4 11: 121 ( de Candolle 1859).

– Type: COLOMBIA • [Nariño Dept.] “Meneses” , Pasto; [1°19′ N, 77°13′ W]; 1851–1857; J.J. Triana 3031; lectotype: K [ K000536693 ], designated by Smith & Schubert (1946b: 87); isolectotypes: BM [ BM001191445 ], BR [ BR0000006957018 ], G, G-DC, P [ P05587374 ].

de Candolle (1864: 285); Smith & Schubert (1946b: 86); Smith (1973: 217); Smith & Wasshausen (1979: 243, 1986: 35).

Etymology

The type specimen of B. pastoensis was collected by J.J. Triana near the city of Pasto in southern Colombia, and the species was named after this locality.

Material examined

PERU – San Martín Region: Prov. Rioja • Bosque de Protección Alto Mayo , unnamed trail from Centro de Interpretación Venceremos (km 382.5) to 381 on highway 5N; 5°39′57″ S, 77°44′54″ W; 1700–1800 m a.s.l.; 5 Jun. 2010; J.L. Clark 11848; US [US01862880], USM • Path through chacra from km 182 of road from Pedro-Ruiz to Rioja; 5°40′01″ S, 77°45′13″ W; 1743 m a.s.l.; 4 Jul. 2018; P.W. Moonlight 1265; E, USM • Bosque de Protección Alto Mayo , Trocha Kovachii ; 5°42′11″ S, 77°45′15″ W; 1805 m a.s.l.; 2 Feb. 2016; P.W. Moonlight & A. Daza 156; MOL, E.

Description

Caulescent herb, to 80 cm high. Stem semi-scandent to erect, rooting at the lower nodes, rarely branching; internodes to 6.5 cm long, to 6 mm thick, succulent, pale green, densely villous. Stipules persistent, broadly-lanceolate, 5–10 × 7–10 mm, apex acute, mucronate, opaque, pale green, glabrous on the inside, hirsute on the outside, margin entire, aciliate. Leaves> 5 per stem, alternate, basifixed; petiole 3–10 cm long, pale green, densely-villous; blade asymmetric, ovate, to 15 × 10 cm, succulent, apex attenuate, base cordate, basal lobes slightly overlapping to overlapping, sinus to 18 mm deep, margin denticulate, sometimes with a cusp on the largest side of the lamina, ciliate, upper surface mid-green, sparsely to densely pilose, lower surface pale green flushed purple, densely-villous on the veins, glabrous to sparsely villous between the veins, veins palmate, 6–8 veined from the base. Inflorescences 1 per stem, bisexual, axillary, erect, cymose, branching up to 4 times, bearing up to 4 staminate flowers and 2 pistillate flowers, protandrous; peduncle to 14 cm long, pale pink, densely villous, bracts persistent, ovate, 12–18 × 12–18 mm, opaque, white to pale green, tinged red, glabrous, apex rounded to obtuse, margin entire, ciliate. Staminate flowers: pedicels to 35 mm long, villous; tepals 4, spreading, outer 2 ovate, 10–19 × 8–18 mm, apex rounded, pink, glabrous, margin serrulate, ciliate, inner 2 lanceolate to broadly-ovate, 10–15 × 6–8 mm, apex rounded, pink, glabrous, margin entire, aciliate; stamens ca 25, spreading, yellow, filaments ca 1mm long, free, anthers ovoid, ca 0.5 × 0.3 mm long, dehiscing via lateral slits, connectives not extended, symmetrically basifixed. Pistillate flowers: pedicels to 30 mm long; bracteoles 2, positioned directly beneath the ovary, ovate, ca 10 × 10 mm, apex rounded, opaque, colour unknown, glabrous, margin entire, aciliate; tepals 5, subequal, persistent in fruit, spreading, elliptic to lanceolate, 8–14 × 4–6 mm, apex obtuse, pink, glabrous, margin entire, aciliate; ovary body broadly-ovoid, 6–8 × 7–10 mm, colour unknown, glabrous to sparsely villous, wings lacking to subequally 3-winged, wings semi-circular 7–9 × 1–3 mm; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow, fused at the base, 3–4 mm long, reniform, stigmatic papillae in a spirally-twisted band. Fruiting pedicel to 30 mm long. Fruit body broadly-ovoid, to 10 × 10 mm, drying brown, wings lacking or expanding to subequal, semi-circular wings to 9 × 9 mm.

Proposed conservation assessment

Known only from two small populations in Peru (<20 individuals observed) but widespread and common across its Colombian and Ecuadorian range. Its total EOO is ca 135 000 km 2 and includes numerous protected areas. We assess B. pastoensis var. pastoensis as Least Concern (LC).

Notes

The three specimens we cite here are the first records of B. pastoensis var. pastoensis from Peru. We cannot be entirely confident about the identification of these specimens, as only a single, open staminate flower and single fruit but no pistillate flowers have been collected in Peru. In all vegetative respects however, these collections are indistinguishable from B. pastoensis var. pastoensis . This species and B. exalata C.DC. share a characteristic, semi-scandent to erect habit, a densely tomentose indumentum, and persistent, broadly lanceolate, reflexed stipules. It differs from B. exalata in its fewer-flowered inflorescences, which branch 3–4 times (compared to 5–6 times in B. exalata ), its much larger outer tepals on the staminate flower (10–19 × 8–15 mm vs 4–6 × 2 mm), and its fruits that sometimes have wings (vs no wings). These three characters are evident on the limited fertile material available, so we feel reasonably confident in identifying this material as B. pastoensis var. pastoensis .

Typification notes

The protologue of B. pastoensis cites J.J. Triana 3031 but no herbarium ( de Candolle 1859: 121), so this this name required lectotypification. Smith & Schubert’s treatment of the Begoniaceae for the Flora of Colombia ( Smith & Schubert 1946b) cited a duplicate in K (K000536693) as the type. This constitutes an effective lectotypification. Smith (1973) later cited a duplicate in G as the holotype while Smith & Wasshausen (1979) cited the duplicate in K as the holotype. Both citations are irrelevant as they are predated by the earlier typification of Smith & Schubert (1946b).

Identification notes

Begonia pastoensis is most similar to Ecuadorian endemic B. exalata C.DC. These two species have frequently been confused on account of their densely villous indumentum and leaves of a similar size and colour. The inflorescences of B. pastoensis branch fewer times than those of B. exalata (3–4 times vs 4–6 times); the flowers of B. pastoensis are much larger (e.g., the staminate flower are 20–42 mm wide vs up to 12 mm wide); and the fruits are winged (vs without wings).

Within Peru, B. pastoensis is one of only a few species of Begonia with a densely long-villous indumentum to its stem. The other species with similar induments are tuberous ( B. heliantha , B. herrerae ) or rhizomatous ( B. erythrothrix Tebbitt & Moonlight ) or else have pinnately veined leaves ( B. hirta (Klotzsch) L.B.Sm. & B.G.Schub. ) or are diminutive annuals ( B. hirtella Link ).

Distribution and ecology

Found from Colombia, Ecuador, and Peru while B. pastoensis var. hirsutior L.B.Sm. is endemic to Venezuela. Within Peru, known from a single population in Rioja Province, San Martín Region ( Fig. 13A ). Found within middle montane forest at an elevation of 1700–1800 m a.s.l., and all collections have been made in the shade of extremely dense montane forests where B. pastoensis var. pastoensis was found growing through dense mats of mosses ( Fig. 14A ). In one locality (P.W. Moonlight & A. Daza 156) these mosses were growing over a limestone cliff whereas in another (P.W. Moonlight 1265) they were growing over a streamside bank and vegetation. The only flower of the species collected in Peru was found in July. The Peruvian records of B. pastoensis var. pastoensis represent a remarkable 500 km disjunction from the remainder of its range. This variety is primarily found from southern Colombia to Bolívar Province, Ecuador. All Ecuadorian records are from the western slope of the Andes and only a few Colombian collections are known form the eastern slope of the Andes. The Andean cordillera is a boundary to the dispersal of mid-elevation Begonia species, so it is difficult to explain how B. pastoensis var. pastoensis could have dispersed between Peru and the rest of its range.

Figures

Fig. 13. Distribution of Begonia sect. Apteron C.DC. in Peru and surrounding countries.A. B. pastoensis var. pastoensis (red). B. B. pedemontana Moonlight sp. nov. (red). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 14. Begonia pastoensis var. pastoensis A.DC. A. Habit. B. Leaf abaxial surface. C. Developing inflorescence. All photographs by P.W. Moonlight from P.W. Moonlight 1265 in Rioja Province, San Martín Region.