Julian A. Steyermark

The vegetation of the Sierra Parima, Venezuela-Brazil: some results of recent exploration

A general outline of the geographical, geological, pedological, and climatic conditions of the Sierra Parima is followed by a description of the natural vegetation in the Venezuelan and Brazilian sections of this mountain range, based on the collections and field experience gathered by the authors during the last 15 years. Special attention is devoted to the savanna vegetation of this upland region, and an attempt is made to explain these non-forest vegetation types from an ecological-historical standpoint. Finally, the possible ecological impact of the autochthonous Yanoama populations on the forest and savanna ecosystems of the Sierra Parima is discussed in the light of data from recent anthropological research.

New species of Rubiaceae from French Guiana, Brazil, and Colombia

Collections from French Guiana, Amazonian Brazil, and Colombia taken in the last 20 years include new species in the following genera:Duroia, Pagamea, Psychotria, Randia, Retiniphyllum, Rudgea, Sabicea, Sipanea, andSphinctanthus. Twenty-one new species are described and five are illustrated.

Revision of the genus Ochthocosmus (Linaceae)

The neotropical genusOchthocosmus is centered in the Guayana Highland of southern Venezuela. The taxonomic history, morphology, ecology, and geographical distribution are discussed in relation to the taxonomy of the genus. A key to the six species and four varieties, distribution maps, descriptions, and specimen citations are given. Two new species and two new varieties are described,O. longipediellatus Steyermark & Luteyn,O. attenuatus Steyermark & Luteyn,O. multiflorus var.angustifolius Steyermark & Luteyn,O. miiltiflorus var.canaripoensis Steyermark & Luteyn; and two new combinations,O. roraimae var.parvifolius (Hallier f.) Steyermark & Luteyn,O. roraimae var.grandifolius (Steyermark) Steyermark & Luteyn, are made.

New species from the summit of Cerro Guaiquinima, Venezuela

Three new species,Lubaria szczerbanii (Rutaceae),Croton guaiquinimae (Euphorbiaceae), andStomatochaeta colveei (Asteraceae), are described from the summit of Cerro Guaiquinima, Venezuela. The generic affinities betweenLubaria andMyllanthus, and betweenStomatochaeta andStenopadus are discussed.

A new species of Raveniopsis (Rutaceae) from Venezuela

Raveniopsis breweri, from the summit of Auyan-tepui, a table mountain of the Venezuelan Guayana Highland, is described. It is the fifteenth species now known in the genus, wholly restricted to the Venezuelan Guayana Highland. A key to all the species described up to the present time is included.

Review of the genus perama (Rubiaceae)

The nomenclatural and taxonomic history of the genusPerama Aubl. (Rubiaceae) is discussed. The major trends of evolution within the genus are characterized, and the sections of the genus are delimited. A new section,Diperama Kirkb. & Steyerm., is described. The distribution of the genus is updated, and centers of species concentration are indicated. A complete synonymy is given for the genus, and the type species cited. An artificial key to the species is given ; a new combination,P. parviflora (Standl.) Kirkb. & Steyerm., is mads; and three new species are described,P. harleyi Kirkb. & Steyerm.,P. irwiniana Kirkb. & Steyerm., andP. sparsiflora Standl. ex Steyerm. & Kirkb.

Revision of the genus joosia (rubiaceae)

Seven species ofJoosia are recognized, four of which are new:J. ulei,J. aequatoria,J. standleyana, andJ. macrocalyx. All of the species are confined to western South America from Colombia south to Peru with the main center of dispersal in Ecuador. A new subgenus,Sectocalyx, is also described.

New rubiaceae from French Guiana

Four new species and one new variety of Rubiaceae from French Guiana are described:Psychotria alloantha, P. cypellantha, P. squamelligera, P. viridibractea, andSipanea ovalifolia var.villosissima.

New taxa from the Avila and Naiguatá Mountains, Venezuela

Ten new species (Billbergia manarae, Croizatia naiguatensis, Croton huberi, Rinorea oraria, Anaectocalyx manarae, Linociera avilensis, Cynanchum beatricis, C. manarae, Matelea costanensis, and M. manarae) are described in preparation for the forthcoming Flora of Avila and Naiguatá.

Revision of the genus Froesia (Quiinaceae)

Froesia venezuelensis, a new species from Venezuela, is described, and the two previously known species ofFroesia are revised.