Notes on Cybianthus Subgenus Cybianthus (Myrsinaceae) in Southeastern Brazil

Abstract

Cybianthus rupestris, a new species from the Planalto of Brazil, is described and illustrated, and its phylogenetic relationships are discussed. Cybianthus glaziovii Mez is placed in synonymy with C. coriaceus Martius; the former binomial is lectotypified, the latter is neotypified, and a complete description is provided for the taxon. The neotropical genus Cybianthus Martius contains approximately 160 species in 10 subgenera (Pipoly, 1987). Cybianthus subg. Cybianthus contains 55 species, distributed across the Amazon Basin, the Guayana Floristic Province (sensu Maguire, 1979), the Guianas, and central and southeastern Brazil. Members of the Grammadenia-Cybianthus-Cybianthopsis clade (Pipoly, 1987) possess basifixed anthers with terminal pores, or with pores that open terminally, then for a short length down each side of the thecae. However, all species of subgenus Cybianthus may at once be recognized by the apparently epipetalous stamens, of which the tube is developmentally fused, or entirely adnate to, the corolla tube; the apically free portions of the filaments range from 1 mm to obsolete. Members of the subgenus are only locally common. My field observations indicate that the number of individuals per population is very low, usually less than 20 individuals per hectare in primary forest. I have seen precocious flowering and architectural reiteration phenomena (sensu Pipoly, 1992), along with sexual variation, in every population thus far observed. The sexual variation observed consists of monoecy, dioecy, and often polygamy in different populations of the same species. Like the majority of Cybianthus species, the flowers are perfect, but functionally unisexual. Historically, the group's systematic biology has been poorly understood owing to a lack of study in population dynamics. In preparation for a treatment of the Myrsinaceae for the Flora da Serra do Cipo, located in Minas Gerais, a remarkable new species was found from the nearby Chapada dos Veadeiros, state of Goias, and is described herewith. Cybianthus rupestris Pipoly, sp. nov. TYPE: Brazil. Goias: Chapada dos Veadeiros, 14?00'S, 47?00'W, ca. 20 km W of Veadeiros [Alto Paraiso], 1,000 m, 10 Feb. 1966 (stam. fl), H. S. Irwin et al. 12841 (holotype, UB; isotypes, LL-TEX, NY). Figure 1. Propter ramulos dense stellato-tomentosos, laminam coriaceam revolutamque, corollae lobos suborbiculares dense prominenteque atro punctatos, C. coriaceo valde affinis, sed ab ea petiolis marginatis (non canaliculatis) 0.7-1 (nec 1.5-3) cm longis, perianthio membranaceo (non chartaceo), calyce inequilater (non equilater) diviso, lobis corollinis subapicale incisuris (non integerrimis) secus margines, glandulari-fimbriatos (nec glandulari-granulosos), antheris glabris (non minute glandulari-papillatis), denique stigmate capitato (non 4-lobato) praeclare distat. Shrub to small tree to 2 m tall, stems to 3 cm diam.; branchlets terete, 3.5-5 mm diam., densely ferrugineous floccose-tomentose, the tomentum composed of stiff, arachnoid-stellate trichomes. Leaves coriaceous, the blades linear-oblanceolate to narrowly oblanceolate, (4-)4.5-9 cm long, 0.8-1.9 cm wide, apex acute, base cuneate, nitid and essentially glabrous above, pallid and densely ferrugineous floccose-tomentose below along the midrib and margin, glabrescent, midrib impressed above, prominently raised below, secondary veins 10-15 pairs, the margin tightly inrolled-revolute, entire; petioles marginate, 0.7-1 cm long, basally pulvinate, glabrous above, densely tomentose below, glabrescent. Staminate infiorescence: a simple, erect raceme, 5-7.5(-8) cm long, the peduncle, rachis and pedicels densely tomentose; peduncle 0.8-1 cm long; floral bracts linear-lanceolate, 1.4-1.8 mm l ng, apex attenuate, densely tomentose above and below, the margin erose, long glandular-ciliate; pedicels cylindrical, thin, 2.8-4.6 mm long. Flowers nodding, 2.6-2.9 mm long, dull yellow-green; calyx membranaceous, cotyliform, 1.2-1.6 mm long, the tube 0.2-0.4 mm long, unequally divided, the lobes suborbicular, 0.7-0.9 mm long, 0.7-1.1 mm wide, apically rounded, hyaline, densely and prominently black punctate-lineate, the margin erose, mostly subapically notched, densely glandular-ciliate, the cilia NOVON 3: 459-462. 1993. This content downloaded from 157.55.39.35 on Mon, 29 Aug 2016 05:02:13 UTC All use subject to http://about.jstor.org/terms