A New Lowland Species of Tropaeolum (Tropaeolaceae) from the Venezuelan Guayana

Abstract

Tropaeolum orinocense from southern Venezuela, the first species in the genus recorded from the upper Orinoco basin, is described. Tropaeolum is a genus of southern temperate origin, with about 90 species native to South and Central America. The tropical and subtropical species are restricted to cool, montane areas, especially in the Andes, except for a few species that enter into coastal lowland Ecuador and Peru. In the most recent monograph of the family (Sparre & Andersson, 1991), no species was reported to occur in lowland Amazonia or Guayana. In 1951, Leon Croizat participated in the FrancoVenezuelan expedition to the headwaters of the Orinoco River and made over 1,000 plant collections. One of these, Croizat 790, was a Tropaeolum growing on the banks of the upper Orinoco at about 300 m elevation. It was reported by Hoist & Todzia (1990) as T. fintelmannii Wagener ex Schldl., a species otherwise known from the Coastal Cordillera of Venezuela and the Andes of Colombia, Ecuador, and Peru. In 1989, as part of a Venezuelan group retracing the previous expedition to the Orinoco headwaters, I found the same Tropaeolum at a single locality along the Orinoco above the mouth of the Rio Ugueto, probably at the same site where Croizat collected it previously. Study of pickled flowers and additional dried specimens showed significant differences from T. fintelmannii and other related species of Tropaeolum. Consequently, the Orinoco collections are described as a new species and the only one known from Amazonian South America. Tropaeolum orinocense P. Berry, sp. nov. TYPE: Venezuela. Territorio Federal Amazonas: Rio Orinoco below Raudal and Salto El Tobogan, above the mouth of Rio Ugueto, 2?14'N, 63?45'W, elevation 370 m, 21 Nov. 1989, Berry 4783 (holotype, MO; isotypes, MYF, TFAV, VEN). Figure 1. Species haec Tropaeolo repando Heilborn affinis, sed floribus minoribus, calcari 24-27 mm longo, petiolo a basi folii 3-5 mm inserto, foliis manifeste quinquelobatis differt. NOVON 2: 182-184. 1992. Slender climbing herb to 5 m long, stem glabrous to lightly strigillose. Leaves peltate, insertion index (ratio of the length of the longitudinal axis of the blade distal to the point of petiole insertion vs. the proximal part) 9:1, stipules lanceolate, ca. 1 mm long; petiole 5-7(-11) cm long, glabrous to strigillose, inserted 3-5 mm from base of leaf; blade thinmembranous, glabrous, light green on upper surface, glaucous on lower surface, + depressed ovate, 3.25.5 cm long, 4.5-9.0 cm wide, the length:width ratio usually 2:3 or less often 1:2, truncate at the base, shallowly 5-lobed, the central 3 lobes shortly mucronate, principal ascending veins 3 from point of petiole insertion, the lateral ones dichotomously branched close to the base. Flowers orange-red, with slender, pendent pedicels 45-75 mm long. Calyx lobes elliptic, the uppermost lobe 5 x 4 mm, the lowermost one 9-10 x 5-6 mm, with a narrowly conical spur either straight or slightly downcurved in distal '/2 to 1/3, the spur 24-27 mm long and 56 mm diam. at point of pedicel insertion. Petals ciliate-dentate at the apex, the cilia 2-2.5 mm long, the upper two petals (opposite the pedicel) cuneate, 5-6 x 3-4 mm (excluding the cilia), the lower three spathulate-unguiculate, the blade 2.5-3.5 x 3-4 mm, somewhat concave, the claw smooth and 5-6 mm long. Stamens 8, slightly uneven, filaments 46 mm long, anthers 2 x 1 mm. Ovary 3-angled; style 2-3 mm long, trifid at apex, one lobe longer than the other two. Mericarps 1(-3?), ca. 5 x 3 mm, brown. Paratypes. VENEZUELA. AMAZONAS: Ugueto, upper Rio Orinoco, Croizat 790 (VEN). Morphologically, this species strongly resembles Tropaeolum repandum Heilborn, a lowland species from coastal Ecuador and northern Peru. The two are very similar in the apical position of the petal cilia and in the shape of the upper and lower petals; the depressed ovate to reniform leaf shape is also common to both species. Tropaeolum orinocense differs, however, in its smaller flowers and the leaves with a higher petiole insertion ratio and a higher length to width ratio. Details of petal coloration, a useful character at the species and sectional level, require further observation of fresh flowers. This content downloaded from 207.46.13.184 on Fri, 29 Jul 2016 05:09:19 UTC All use subject to http://about.jstor.org/terms Volume 2, Number 3 1992 Berry Tropaeolum 183