Solanum maternum (Solanaceae), a New Bolivian Relative of the Tree Tomato

Abstract

A new species endemic to Bolivia, Solanum maternum, is described. Solanum maternum belongs to a group of taxa formerly recognized as the genus Cyphomandra. Solanum maternum is morphologically very similar to the tree tomato, Solanum betaceum, and may be its closest wild relative. The former genus Cyphomandra Sendtner encompasses a group of about 30 species of shrubs and small trees with usually large, pendent fruits. The group is characterized by the presence of an enlarged connective region on the abaxial anther surface; this structure may play a role in pollination by secreting volatile compounds that attract male euglossine bees (Gracie, 1993; Sazima et al., 1993; Soares et al., 1989). Other characteristics of the Cyphomandra group that occur in most, but not all, species include Prdvost's architectural model, very large chromosomes, and gametophytic self-incompatibility (Bohs, 1994). Recent molecular evidence indicates that the Cyphomandra group is nested within Solanum (Bohs & Olmstead, 1997; Olmstead & Palmer, 1992, 1997; Spooner et al., 1993), and all Cyphomandra species have now been transferred or returned to Solanum (Bohs, 1995), where the first described species were placed. The infrageneric taxonomy of Solanum is currently under study and no infrageneric rank is consistently used at present for the Cyphomandra group. The monophyly of the Cyphomandra group and the relationship of this group to others within Solanum, particularly its putative sister group, Solanum sect. Cyphomandropsis Bitter, are issues that need to be examined before a taxonomic designation is made. Species of the Cyphomandra group have been of interest because many produce edible fruits that are gathered from the wild or grown as minor crops. The most important in this regard is Solanum betaceum Cavanilles, the tree tomato, which is frequently cultivated in Latin America and commonly sold in Andean markets. Solanum betaceum has also been an item in international commerce, usually sold under the name tamarillo. Until recently, little was known about the place of origin of the tree tomato, which is usually regarded as being a cultigen. A group of species from Bolivia has now been identified as the closest wild relatives of S. betaceum, based on morphological and crossing data (Bohs, 1991, 1994). The species described here is a new member of this species complex and bears great morphological similarity to S. betaceum. Evidence presented below indicates that the new species is interfertile with S. betaceum and with two other members of the S. betaceum species complex. Solanum maternum Bohs, sp. nov. TYPE: Bolivia. Santa Cruz: Prov. Caballero, Siberia-El Empalme, 5 km entrando hacia Khara Huasi, carretera entre Comarapa-Cochabamba, 17o50'S, 64?43'W, 2300 m, 8-9 May 1992 (fl, fr), I. Vargas & E. Prado 1273 (holotype, NY; isotypes, DUKE, MO not seen, USZ not seen). Figure 1. Solano betaceo Cavanilles affine, a quo differt corollis albo-purpureis, fructibus maturis luteis, pube paulo sparsiore, connectivis antherarum paulo latioribus. Small tree or shrub 1-4 m tall. Branches and petioles moderately to densely puberulent with glandular and eglandular unbranched hairs less than 1 mm long. Leaf blades simple, unlobed, chartaceous, acuminate at apex, moderately puberulent adaxially, more densely so on veins, densely puberulent abaxially. Trunk leaves with blade ovate, 19-34 cm long, 15-24 cm wide, length:width ratio ca. 1.5:1, the base cordate with basal lobes 1-4 cm long; petioles 11-22 cm long. Crown leaves 4 per sympodial unit, the blade ovate, 6.5-21 cm long, 5-14 cm wide, length:width ratio ca. 1-1.5:1, the base cordate to auriculate with basal lobes 1-3 cm long; petioles 2.5-11 cm long. Inflorescence unbranched or branched, ca. 20-60-flowered, 5-10 cm long; peduncle 3-4 cm long; rachis 2-8 cm long; pedicels ca. 15-20 mm long, 20-35 mm long in fruit, ca. 1-10 mm apart, articulated above the NovoN 7: 341-345. 1997. This content downloaded from 157.55.39.64 on Fri, 22 Jul 2016 04:00:23 UTC All use subject to http://about.jstor.org/terms