Begonia vargasii Moonlight, 2023

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 : 96-98

18. Begonia vargasii Moonlight sp. nov.

urn:lsid:ipni.org:names:77323291-1

Figs 24C , 34

Diagnosis

Most similar to Begonia oblanceolata Rusby but differing in its aciliate stipules and bracts (vs long-ciliate), the rounded to obtuse apices of the tepals of its staminate flowers (vs acuminate), its two bracteoles (vs one), its ovoid fruit body (vs obdeltoid), and its non-ascending fruit-wings (vs ascending).

Etymology

The species is named for the late Peruvian botanist Julio César Vargas Calderón, who collected the type specimen and is responsible for many of the unique or unusual collections of Begonia from Peru, particularly those from Cusco Region.

Type

PERU – Cusco Region: Prov. Calca • Mant’o, km 84; 12°59′ S, 72°04′ W; 2040 m a.s.l.; 19 Jun. 1964; J.C. Vargas Calderón 15616; holotype: US [ US00222362 ] .

Description

Caulescent herb, to at least 30 cm high. Stem erect, branching; internodes to 5.5 cm long, to 4 mm thick, succulent, colour unknown, glabrous. Stipules in unequal pairs, persistent, lanceolate to broadly ovate, clasping the stem, 10–32 × 4–6 mm, apex acute, base asymmetrical, auriculate on the broad side, cuneate on the narrow side, translucent, pale brown, glabrous, margin entire, aciliate. Leaves> 5, alternate, basifixed; petiole 0.8–2.2 cm long, colour unknown, glabrous; blade asymmetric, ovate, to 8 × 3.2 cm, succulent, apex acuminate, base transversely truncate, margin serrulate, ciliate, upper surface bright green, glabrous, lower surface pale grey-green, glabrous, veins palmate-pinnate, 4–6 veined from the base, with 2–4 secondary veins on the larger side, 1–3 secondary veins on the smaller side. Inflorescences 1–3 per stem, bisexual, axillary, erect, cymose, with 2 branches, bearing up to 4 staminate flowers and 4 pistillate flowers, protandrous; peduncle to 2.8 cm long, colour unknown, glabrous, bracts persistent, lanceolate, 3–6 × 1–2 mm, translucent, colour unknown, glabrous, apex acuminate, margin entire to serrulate, ciliate to aciliate at the apex. Staminate flowers: pedicels to 19 mm long, glabrous; tepals 2, spreading, broadly ovate, 10–12 × 8–13 mm, apex obtuse, colour unknown, glabrous, margin entire, aciliate; stamens ca 40, spreading, yellow, filaments 0.5–2.5 mm long, free, anthers ellipsoid, 1–1.5 × 0.75 mm, dehiscing via lateral slits, connectives extending to 0.5 mm, symmetrically basifixed. Pistillate flowers: pedicels to 8 mm long; bracteoles 2, lanceolate to ovate, 1.5–2.5 × 0.5–1.5 mm, translucent, colour unknown; tepals 5, subequal, deciduous in fruit, spreading, elliptic to ovate, 2.5–6 × 1.5–3 mm, apex rounded to acute, colour unknown, glabrous, margin entire, aciliate; ovary body ovoid, ca 3 × 1.5 mm, colour unknown, glabrous, unequally 3-winged, wings triangular, largest ca 4 × 2 mm, smallest ca 4 × 1 mm; 3-locular, placentae branches divided, bearing ovules on both surfaces; styles 3, yellow, free, ca 2.5–3 mm long, irregularly 2-3 times-divided, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 23 mm long. Fruit body ovoid, to 9 × 6 mm, drying brown, wings same shape as in ovary, the largest expanding 8 × 16 mm, the smallest expanding to 8 × 4 mm.

Proposed conservation assessment

Known from a single specimen, which was collected in a relatively undisturbed area. Little is known about the population size of this species, which we assess as Vulnerable (VU D2) due to its small known range.

Identification notes

Most similar to B. oblanceolata (see Diagnosis) but, within Peru, most similar to B. obtecticaulis . It is readily distinguished by its serrulate (vs irregularly double dentate) leaf margins and its asymmetrical stipules, which are auriculate on the broad side and cuneate on the narrow side (vs symmetrical, cuneate on both sides). This character is shared with B. imbrexiformis sp. nov., but B. vargasii sp. nov. is readily distinguished from this species by its palmate-pinnate (vs pinnate) leaf venation.

Distribution and ecology

Endemic to Peru and Cusco Region ( Fig. 24C ). Found in middle montane forest at an elevation of 2040 m a.s.l. Begonia vargasii sp. nov. may be most common on the edge of montane forest patches in common with most of its relatives.

The stenotepala group of Begonia sect. Cyathocnemis

We define herein the stenotepala group of B. sect. Cyathocnemis , including members of the section with five tepals in the pistillate flower (except some individuals of B. subspinulosa ) and bifurcating styles but lacking notches in their largest fruit wings. There are seven members of the group and all are found in Peru ( B. alto-peruviana A.DC. , B. brevicordata , B. deltoides Moonlight sp. nov., B. longitepala Moonlight sp. nov., B. lucifuga Irmsch. , B. stenotepala L.B.Sm. & B.G.Schub. , B. subspinulosa ) with the range B. alto-peruviana extending into northern Bolivia. The centre of diversity for the group is the Cusco Region of Peru and most species are found at low densities in the understories of dense lower montane forest. Perhaps as a consequence of this, only three species are known from> 5 specimens. Species delimitation within the group is difficult as few specimens have been collected with all three of staminate flowers, pistillate flowers, and fruits.

Figures

Fig. 24. Distribution ofBegonia sect.Cyathocnemis (Klotzsch)A.DC. in Peru and surrounding countries. A. B. amoeboides Moonlight (red) andB. imbrexiformis Moonlight sp. nov. (blue).B. B. bracteosaA.DC. (red) and B. longinqua Moonlight (blue). C. B. cyathophora Poepp. & Endl. (red), B. serratistipula Moonlight sp. nov. (blue) and C. vargasii Moonlight sp. nov. (green). D. B. lamolina Moonlight (red), B. lophoptera Rolfe (blue) and B. obtecticaulis Irmsch. (green). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 34. Begonia vargasii Moonlight sp. nov. A. Habit. B. Staminate flower, front view. C. Staminate flower, side view. D. Close up of stigma and style. E. Pistillate flower, side view. Illustration by Anna Dorward from J.C. Vargas Calderón 15616 (US).