Begonia deltoides 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 : 103-105

21. Begonia deltoides Moonlight sp. nov.

urn:lsid:ipni.org:names:77323292-1

Figs 35B , 36

Diagnosis

Most similar to B. stenotepala but differing in its deltoid leaf laminae (vs transversely ovate) with serrate (vs entire to serrulate) margins; its smaller stipules (8–12 × 2–6 mm vs 12–35 × 5–8 mm); and its staminate flowers staminate flowers with fewer stamens (15–20 vs ca 30) and smaller (ca 7 × 4.5 mm vs 5–18 × 4–8 mm) red brown tepals with an obtuse apex (vs bright red or orange with an acuminate apex).

Etymology

From the triangular Greek letter Delta (Δ), referring to the distinctive triangular or deltoid outline of the species’ leaves.

Type

PERU – Puno Region: Prov. Carabaya • Km 11 of road from San Gabán (=Lanlacuni Bajo) to Macusani ; [13°31′ S, 70°26′ W]; 1000 m a.s.l.; 19 Oct. 1984; P.J.M. Maas, H. Maas, C. Roersch, L.Y.T. Westra 6096; holotype: USM; isotypes: U [ U1144397 ].

Specimens examined

PERU – Cusco Region: Prov. La Convención • Dist. Camanti, Vitobamba , SE of Quincemil, km 234 on main highway Quincemil-Cusco, Bocatoma’ 13.3183°S, 70.8156°W; 800–1000 m a.s.l.; 16 May 2010; J.L. Clark, L. Clavijo, J. Janovec, M. Overstreet & J. Wells 11468; US [ US01176971 ], USM. – Puno Region: Prov. Sandia • Oroya-Santo Domingo trail ; [13°51′ S, 69°30′ W]; 13 May 1943; W.H. Hodge 6029; US [ US00967198 ], USM • Near Sagrario ; [13°55′ S, 69°41′ W]; 1000–1300 m a.s.l.; 26 May 1942; R.D. Metcalf 30630; MO [ MO-2264411 ], US [ US00222355 ] • San Juan de Oro, atque per viam usque ad Seito-Cocha cerca pagum; [14°14′ S, 69°10′ W]; 1400–4350 m a.s.l.; 23–25 Oct. 1976; L. Bernardi, A. Charpin & F. Jacquemoud 16803; G .

Description

Caulescent herb, to 40 cm high. Stem erect, occasionally branching; internodes to 9 cm long, to 5 mm thick, succulent, maroon, glabrous. Stipules persistent, ovate, 8–20 × 2–11 mm, apex obtuse, mucronate, opaque, brown, glabrous, margin entire, aciliate. Leaves 2–5 per stem, alternate, basifixed; petiole 1–4.5 cm long, maroon, sparsely pilose; blade asymmetric, deltoid, to 14 × 7 cm, membranaceous, apex acuminate, base truncate, basal lobes angular on the wider side, cuneate on the narrow side, sinus to 2.5 mm deep, margin irregularly dentate, ciliate, upper surface green, glabrous, lower surface maroon, glabrous, veins palmate-pinnate, 4–6 veined from the base, with 4–6 secondary veins on the larger side, 2–4 secondary veins on the smaller side. Inflorescences 2–4 per stem, bisexual, axillary, erect, cymose, with 4 branches, bearing up to 8 staminate flowers and 8 pistillate flowers, protandrous; peduncle to 14 cm long, light brown, glabrous, bracts deciduous, broadly ovate, 3–4 × 1.5–4 mm, translucent, light brown, glabrous, apex rounded, margin serrulate, ciliate. Staminate flowers: pedicels to 4 mm long, glabrous; tepals 2, spreading, ovate, 5–9 × 4.5–6 mm, apex obtuse, red-brown, glabrous, margin entire, aciliate; stamens 15–20, projecting, yellow, filaments 1–1.5 mm long, free, anthers ellipsoid, ca 1.5 × 0.5 mm, dehiscing via lateral slits, connectives extended to ca 0.5 mm, symmetrically basifixed. Pistillate flowers: pedicels to 15 mm long; bracteoles 3, positioned directly beneath the ovary, ovate, ca 5 × 3 mm, apex rounded, translucent, colour unknown, glabrous, margin lacerate, ciliate; tepals 5, subequal, deciduous in fruit, spreading, elliptic, 4–7 × 2.5–4 mm, apex acuminate, red brown, glabrous, margin entire, aciliate; ovary body ovoid, ca 5 × 2.5 mm, colour unknown, glabrous, unequally 3-winged, largest wing rectangular, ca 7 × 2.5 mm, smallest two marginal ca 2 mm wide; 3-locular, placentae unknown; styles 3, colour unknown, free, 3 mm long, once-divided, stigmatic papillae in a spirally twisted band. Fruiting pedicel to 17 mm long. Fruit body ovoid, to 8 × 5 mm, drying brown, unequally 3-winged, the largest triangular, expanding to 12 × 15 mm, the smallest triangular, expanding to 8 × 4 mm.

Proposed conservation assessment

Known with certainty from three populations with a combined EOO of ca 1000 km 2. We have not observed this species in the field and its sparse collection record suggests it is found either at low densities or in localised populations. We assess B. deltoides sp. nov. as Vulnerable (VU D2) due to its small number of known populations.

Notes

The sectional placement of B. deltoides sp. nov. is unclear, primarily because we know of no collections with pistillate flowers. Its erect habit and palmately nerved leaves strongly suggest the species is either a member of B. sect. Cyathocnemis or B. sect. Hydristyles, which are distinguished by whether their styles are bifid or multifid, respectively. The styles of this species are persistent and remain on the fruits at maturity but are generally desiccated and reduced in size. Irrespective, the persistent styles are bifid, so we place B. deltoides sp. nov. in B. sect. Cyathocnemis . Within this section, the persistent stipules and staminate flowers with relatively long and thin, coloured tepals are reminiscent of the stenotepala group so we tentatively place the species here.

Identification notes

Begonia deltoides sp. nov. is superficially similar to B. unduavensis Rusby , which is endemic to Bolivia. Both species have deltoid leaves, but B. deltoides sp. nov. is glabrous throughout while both surfaces of the leaves of B. unduavensis are sparsely pilose. The two species differ in their flowers as B. deltoides sp. nov. has staminate flowers with 15–20 stamens (vs ca 75 stamens) and pistillate flowers with bifid styles (vs multifid styles).

Within Peru, B. deltoides sp. nov. is most similar to B. stenotepala (see Diagnosis) but these species are unlikely to be confused on account of their very different leaf shapes and flower colours. Begonia deltoides sp. nov. is more likely to be confused with B. fischeri , which is a similar sized species with deltoid leaves. Begonia fischeri is a more delicate, succulent annual or perennial whereas B. deltoides sp. nov. is a more robust perennial. In flower, they are easy to distinguish as the tepals of B. fischeri are white, while those of B. deltoides sp. nov. are red brown.

Distribution and ecology

Known with certainty only from Peru and Puno Region ( Fig. 34B ). Found within lower montane forest at an elevation of 1000–1400 m a.s.l. and possibly higher (see L. Bernardi, A. Charpin & F. Jacquemoud 16803).

Figures

Fig. 35. Distribution of the stenotepala group of Begonia sect. Cyathocnemis (Klotzsch) A.DC. in Peru and surrounding countries. A. B. alto-peruviana A.DC. (red). B. B. brevicordata L.B.Sm. & B.G.Schub. (red), B. deltoidesMoonlight sp. nov. (blue), and B. lucifuga Irmsch (green). C. B. longitepalaMoonlight sp. nov. (red) and B. subspinulosa Irmsch. (blue). D. B. stenotepala L.B.Sm. & B.G.Schub. (red). Black lines indicate country borders, grey lines indicate major administrative divisions, blue lines indicate rivers, and shading indicates elevation.

Fig. 36. Begonia deltoides Moonlight sp. nov. A. habit. B. leaf, adaxial surface. C. staminate flower, front view. D. staminate flower, side view. E. pistillate flower, side view. Illustration by Anna Dorward from W.H. Hodge 6029 (US).

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).