Baynesia, a New Genus of Stapeliad from the Northwestern-Most Corner of Namibia (Apocynaceae)

Abstract

A new genus of stapeliad, Baynesia (Apocynaceae-Asclepiadoideae-Ceropegieae), is described with a single species, B. lophophora Bruyns. This is known from the mountainous area in the northwestern-most corner of Namibia, where it was relatively plentiful but very local. Its relationships to Caralluma R. Brown and Pseudolithos P. R. O. Bally are discussed. At present the group of highly succulent plants known as the stapeliads is considered to form a monophyletic group within the Ceropegieae, and it consists of 25 genera (Bruyns, 2000). The present new species does not fit comfortably into any of these genera, and consequently it is placed in a new genus, Baynesia. Its closest relationships appear to lie with Caralluma and Pseudolithos; the differences between them are discussed in detail. Baynesia Bruyns, gen. nov. TYPE: Baynesia lophophora Bruyns, sp. nov. A Caralluma caulis rugulosis et papillatis differt; a Pseudolithos pagina caulium sine polygonis elevatis, praesentia interdum denticulorum stipularium et pollinario multum dissimili distinguenda est. Dwarf spineless clump-forming succulent 3080(-150) mm diam. Stems erect, not rhizomatous, fleshy and fairly soft, glabrous, somewhat transversally rugulose and finely papillate, 30-80 x 6-12 mm, green to suffused with brown; tubercles obscurely conical, slightly spreading, fused into 4 obtuse and obscure angles along stem with concave area between them; leaf-rudiment spreading, caducous, cordate-acute, 1.0-1.5 mm long, inserted just below base of next tubercle, with very occasional stipular denticles. Inflorescences glabrous, usually 3-10 per stem, arising toward apex, each bearing 1-3(-5) flowers developing in gradual succession, without peduncle, with minute linear bracts < 1 mm long without lateral teeth; pedicel 1.5-2.5 x < 1.0 mm, descending and holding flower facing partly downward, usually somewhat longitudinally ridged, suffused with red; sepals lanceolate, acuminate, ca. 1.5 x 0.5 mm. Corolla campanulate, 3-4 X 6-8 mm; outside smooth and glabrous, pale green suffused with red; inside deep maroon becoming cream in lower half of tube, glabrous, papillate only in two lines along edges of fold in lobes (? around mouth of tube); tube ? hemispherical, ca. 1.5 x 3-4 mm; lobes erect, ca. 2 x 2 mm, ovate-acute, folded along midrib so that inside crested toward apex, apex recurved, without marginal cilia. Corona ca. 1 x 2 mm, consisting of 2 series of lobes arising from staminal tube and close together on it, glabrous, with very short basal stipe; outer lobes deltoid, acute, ca. 0.5 mm long and broad, spreading, dark maroon in patch beneath guide-rail, otherwise transparent; inner lobes adpressed to backs of anthers and mostly equaling them, dorsiventrally flattened and slightly convex above, obtuse, ca. 0.5 mm long, with obtuse swollen dorsal projection between outer lobes, cream. Anthers horizontal on top of style-head, margins shrinking back to expose pollinia, rectangular. Pollinium ellipsoidal, much broader than long, insertion crest exactly along outer edge, caudicle minute. Follicle 25-35 x 2.5-3.5 mm, glabrous, smooth, faintly streaked with brown on creamgreen. Seeds 5 x 1.5-2.0 mm, uniformly pale brown, with margins folded upward. Baynesia lophophora Bruyns, sp. nov. TYPE: Namibia. Kaokoveld, Baynes Mtns. near the Cunene River, Dec. 1999, P V Bruyns 8000 (holotype, BOL; isotypes, K, MO, PRE, WIND). Figures 1, 2. Species unica, a speciebus Caralluma lobis corollae porcatis cristatisque et pollinario polliniis insolenter latis corpusculoque alis lateralis minutis differt. Distribution and habitat. This new species is, at present, known only from the north-facing aspects of the higher parts of the Baynes Mountains overlooking the Cunene River in the northwestern corner of Namibia. Here it occurs at an altitude of 1500-1600 m just above the large, sandstone cliffs that dominate the landscape in this area. The vegetation of these cliffs is quite different from that of the surroundings and consists mainly of succulents. Species such as Aloe corallina VerNovoN 10: 354-358. 2000. This content downloaded from 157.55.39.44 on Sat, 24 Sep 2016 04:13:54 UTC All use subject to http://about.jstor.org/terms 100* Missouri Botanical Garden Baynesia lophophora (Apocynaceae), a new genus and species. (See page 355.) A Journal for Botanical Nomenclature