Three New Species and a New Combination in the Asclepiadaceae from the Venezuelan Guayana

Abstract

In preparation of the Asclepiadaceae treatment for the Flora of the Venezuela Guayana, one new species of Matelea, M. stergiosii, and two new species of Ditassa, D. ottohuberi and D. verticillata, are herein described. A new combination is also made in Ditassa, D. bolivarensis. Matelea stergiosii Morillo, sp. nov. TYPE: Venezuela. Estado Bolivar: moist forest on rocky slopes, near Campamento Auraima, Rio Paragua, 6022'30N, 63?33'30W, 330 m, MayJune 1987, Stergios 10450 (holotype, VEN; isotypes, MO, MY, NY, PORT). Figure 1. Species haec Matelea squiresii (Rusby) Morillo proxima, sed recedit: foliis late ovato-ellipticis vel obovatoellipticis, corolla 7.8-10 mm diametro, corollae lobis, 33.4 mm longis, 2.4-3.2 mm latis, intus breviter et dense puberulentis, gynostegio, 1.6-1.65 mm alto, 2.3-2.6 mm diametro (0.95-1.2 mm alto et 1.55-1.95 mm diametro in M. squiresii); antheris 1.4 mm latis; coronae segmentis basi 1.2-1.25 mm latis. Twining vine; stems with short and inconspicuous pubescence in two rows; leaves opposite; petioles 0.5-1.3 cm long, puberulent, blades broadly ovateelliptic to obovate-elliptic, 3-5.5 x 1.2-3.3 cm, apex usually ? abruptly acuminate, base obtuse to cuneate, glabrous except for a few hairs along the midvein above, 5 or 6 pairs of lateral veins, 4 nectaries at the base. Inflorescence subaxillary, 2or 3-flowered; peduncle 1-2 mm long, bracts ovate, 0.6-0.7 mm long, ciliate along the margins; pedicels 2-2.5 mm long, glabrous. Calyx lobes ovate-elliptic, 1.8-2 x 1.1-1.3 mm, with few short, curved hairs outside and short cilia along the margins, the apex narrowly obtuse. Corolla rotate, 7.8-10 mm diam., the lobes 3-3.4 x 2.4-3.2 mm, apparently green and brown, densely short-appressed or erect-puberulent inside, with few short, curved hairs along a medial line outside, the apex obtuse. Gynostegium shortly stipitate, 1.6-1.65 mm long (tall) and 2.32.6 mm diam.; anthers horizontal, 1.3-1.4 mm wide. Pollinia horizontal, irregularly and narrowly ovate-truncate, 0.45 x 0.3 mm, caudicles 0.20.25 mm long, corpusculum narrowly sagittate, 0.2 x 0.1-0.12 mm. Corona formed by 5 columnshaped segments, which are basally expanded, the NOVON 2: 30-32. 1992. basal part 1.2-1.25 mm wide, margin almost entire. Fruits unknown. This species belongs to a difficult complex with Matelea squiresii, which is known from southern Venezuela and the Guianas (also probably in Brazil) from lowland moist forests. Matelea stergiosii differs clearly in the somewhat wider leaf blades, much wider corolla, and gynostegium and inner face of the corolla lobes with denser pubescence. Ditassa ottohuberi Morillo, sp. nov. TYPE: Venezuela. Territorio Federal Amazonas: summit of Cerro Coro-Coro, NW headwaters of Rio Manapiare, NW section of Serrania de Yutaje, 5?46'N, 66?12'W, 2,200 m, Nov. 1987, Huber 12290 (holotype, VEN; isotypes, MO, MY, NY, RB, TFAV). Species nostra Ditassae acerifoliae Lasser et Maguire affinis, sed differt: corolla subcampanulata, 1.9-2 mm diametro, lobis 1.3-1.4 x 0.8-0.9 mm; gynostegio breviter tipitato 0.6-0.65 mm longo; antherae alis 0.260.32 mm longis, corona exteriori segmentis oblongis vel anguste triangulari-oblongis, 0.65-0.75 x 0.2 mm, corona interiori segmentis 0.2 mm longis. Erect suffruticose plant, 20-30 cm high; stems shortly branched, branches rugose, the lower part with conspicuous persistent petiole bases, internodes 0.5-1 mm long, minutely erect-puberulent. Leaves apparently disjunctly verticillate or subspirally arranged, erect, up to 8 per whorl; petioles 0.6-1.8 mm long, decurrent, glabrous; blades fleshy, ? linear, roundly triquetrous in cross section, 0.8-1 x 0.05-0.07 cm, the apex mucronate, the base gradually cuneate, the surface glabrous, veins and nectaries not evident. Inflorescences axillary or interpetiolar, cymose, 1-3-flowered; peduncles 0.6-1.6 mm long, glabrous, bracts and bracteoles narrowly ovate, 0.6-1 mm long, glabrous; pedicels 2.5-2.6 mm long, glabrous. Calyx lobes narrowly ovate, 1.11.5 x 0.45-0.55 mm, obtuse. Corolla subcampanu ate, 1.9-2 mm diam., the tube 0.5-0.6 mm long, glabrous, the lobes obliquely ovate, somewhat concave, suberect in anthesis, 1.3-1.4 x 0.8-0.9 mm, glabrous outside, puberulent-papillose inside, the apex narrowly obtuse. Gynostegium shortly stipitate, 0.6This content downloaded from 157.55.39.141 on Sun, 11 Dec 2016 04:52:49 UTC All use subject to http://about.jstor.org/terms Volume 2, Number 1 1992