Three new species of Begonia (Begoniaceae) from Bahia, Brazil

Abstract The taxonomic treatment of Begoniaceae for the state of Bahia, Brazil, led to the recognition of three new species of Begonia with narrow distributions, which are described and illustrated here: Begonia delicata Gregório & J.A.S. Costa, sp. nov. is a herb restricted to the region of the Recôncavo; Begonia elianeae Gregório & J.A.S. Costa, sp. nov. is a shrub endemic to the Atlantic forest of the southern part of the state; and Begonia paganuccii Gregório & J.A.S. Costa, sp. nov. is a subshrub known only from the type material, collected in the Piedmont of Paraguaçu. Notes on morphology, comparisons with morphologically similar species, etymology, geographic distribution, habitat and phenological data for each species are also presented. Furthermore, keys are provided as an aid to separating the new species from congeneric species that occur in their surroundings. Due to the sparse knowledge of the new species, there is as yet insufficient data to accurately assess their conservation status.


Introduction
Begonia L. is one of the largest genera of Angiosperms (~1,500 species), known worldwide as ornamentals, with numerous hybrids and cultivars popular in the horticultural market (Neale et al. 2006). Th e genus probably arose in Africa but is most diverse in the Americas and Asia (Goodall-Coopestake et al. 2010), occurring in a variety of habitats, but mainly in moist and shady forests (Clement et al. 2004). Taxonomically, it is arranged in more than 60 sections (Doorenbos et al. 1998). Nevertheless, these sections are not morphologically consistent and diagnostic features of one section are often found in members of other sections (Forrest et al. 2005). Although phylogenetic studies in Begonia have been based on low density, world-wide sampling (e.g., Forrest et al. 2005) or focused only on species of certain Old World regions (e.g., Plana 2003;Th omas et al. 2011), several sections of Begonia were already shown to be poly-or paraphyletic, and the sectional circumscription of Neotropical groups appears to be highly problematic (Dewitte et al. 2011).
Etymology. Th e epithet refers to the fragility and delicacy of the plant. Distribution and habitat. Begonia delicata occurs exclusively in the Recôncavo region (Fig. 2). It is known by only two collections, both from Serra da Copioba, the most recent made in 1953, growing on rocks covered by moss. It has not been found in conservation unit.
Distribution and habitat. Begonia elianeae was found in three localities in southern Bahia, in areas of Atlantic rainforest (Fig. 2), growing on rocks, near pastures or eventually supported by tree trunks, on the edge of trails or disturbed forests. It has not been found in conservation units.
Phenology. Flowering in May, August and October, and with fruits in May and October.
Etymology. Th is species is named in honour of Dr. Luciano Paganucci de Queiroz, a great expert on the fl ora of Bahia, who collected the type material.
Distribution and habitat. Begonia paganuccii is known from a single collection from the Área de Relevante Interesse Ecológico (ARIE), a protected area in the municipality of Itaberaba (Fig. 2), region of the Piedmont of Paraguaçu, growing in seasonal forest at 783 m a.s.l. Nevertheless, agriculture and livestock are common around and within the conservation unit.
Phenology. Flowering and fruiting in August. Discussion. Begonia paganuccii is characterised by a dendritic indumentum, stipules lanceolate, and transversally elliptic leaf-blades, 6-or 7-lobed. Trichomes are quite important in the taxonomy of Begoniaceae when combined with other morphological information (Jacques 2002). Some species in Brazil have dendritic trichomes, such as Begonia egregia N.E. Br and B. lindmanii Brade. Begonia paganuccii diff ers from B. egregia by the basifi xed, lobed and transversally elliptic (vs. peltate, entire and ovate to elliptic) leaf-blade, staminate fl owers with 4 tepals (vs. 2) and pistillate fl owers with trilocular ovary and 3 styles (vs. ovary tetralocular and with 4 styles). It also diff ers from B. lindmanii by the lobed (vs. entire) leaf-blade, as well as by the many-fl owered dichasial cyme (ca. 180 fl owers vs. 10-15 fl owers) and pistillate fl owers with 2 bracteoles (vs. 3 bracteoles). Th is species can be distinguished from the remaining species of Begonia from the region where it occurs using the key below. Due to the leaves with cystoliths and the entire placenta, it most likely belongs to the sect. Pritzelia (Klotzsch) A. DC.
Key to the species of Begonia from Itaberaba, Piedmont Region of the Paraguaçu basin