Artículo de publicación ISIA high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groupsConsejo Nacional de Ciencia y Tecnologia 000000000011820

The role of Pleistocene climate changes in promoting evolutionary diversification in global biota is well documented, but the great majority of data regarding this subject come from North America and Europe, which were greatly affected by glaciation. The effects of Pleistocene changes on cold- and/or dry-adapted species in tropical areas where glaciers were not present remain sparsely investigated. Many such species are restricted to small areas surrounded by unfavourable habitats, which may represent potential interglacial microrefugia. Here, we analysed the phylogeographic structure and diversification history of seven cactus species in the Pilosocereus aurisetus complex that are restricted to rocky areas with high diversity and endemism within the Neotropical savannas of eastern South America. We combined palaeodistributional estimates with standard phylogeographic approaches based on two chloroplast DNA regions (trnT-trnL and trnS-trnG), exon 1 of the nuclear gene PhyC and 10 nuclear microsatellite loci. Our analyses revealed a phylogeographic history marked by multiple levels of distributional fragmentation, isolation leading to allopatric differentiation and secondary contact among divergent lineages within the complex. Diversification and demographic events appear to have been affected by the Quaternary climatic cycles as a result of isolation in multiple patches of xerophytic vegetation. These small patches presently harbouring P. aurisetus populations seem to operate as microrefugia, both at present and during Pleistocene interglacial periods; the role of such microrefugia should be explored and analysed in greater detail.

The Melocactus spp. displayed levels of genetic variability lower than the values reported for other cactus species. The evidence indicates the occurrence of introgression in both species at two sites. The high F(ST) values cannot be explained by geographical substructuring, but are consistent with hybridization. Conversely, morphological differentiation in M. paucispinus, but not in M. concinnus, is probably due to isolation by distance.

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From 1990 to 2006, 2,875 new angiosperm species were described in Brazil, including 280 new Bromeliaceae species. This publication rate is considered to be a useful indicator of floristic richness and also reveals the huge gaps in our knowledge of species that make up Brazilian biomes and the importance of taxonomy as a basic tool to assess biodiversity and conservation. The goal of modern taxonomists is in a race against time ordained by an unprecedented rate of global biodiversity loss, and therefore collaboration is vital to successfully close these gaps. This paper is the result of a broad cooperative research effort undertaken specifically to provide basic data on the identity of new components of Brazilian biological diversity. The authors describe and illustrate 22 new Bromeliaceae species from three subfamilies: Bromelioideae -Aechmea guaratingensis, A. paratiensis, A. rubroaristata, Cryptanthus capitellatus, C. venecianus, C. viridovinosus ResumoNo Brasil, entre 1990 e 2006, foram descritas 2.875 novas espécies de angiospermas, incluindo 280 novos membros para a família Bromeliaceae. Esses números constituem um indicador tanto da riqueza florística do país, como também da grande lacuna de conhecimento das espécies que compõem os biomas brasileiros, ao mesmo tempo em que destacam a importância da taxonomia como uma ferramenta de base no âmbito da catalogação da biodiversidade e da conservação. A tarefa dos taxonomistas modernos é hoje ditada por uma verdadeira corrida contra o tempo em razão da perda global da biodiversidade sem precedentes. Nesse processo, a colaboração é vital para suprir as lacunas do conhecimento. Este trabalho é o resultado de um amplo esforço cooperativo de pesquisa que tem o propósito de fornecer dados básicos sobre a identidade de novas espécies que compõem a biodiversidade brasileira. São aqui descritas e ilustradas 22 espécies novas de Bromeliaceae, pertencentes a três subfamílias e nove gêneros: Bromelioideae -Aechmea guaratingensis, A. paratiensis, A. rubroaristata, Cryptanthus capitellatus, C. venecianus, C. viridovinosus, Hohenbergia aechmeoides, H. arcuata, H. barbarespina

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Allozyme diversity and morphometrics of the endangered Melocactus glaucescens (Cactaceae), and investigation of the putative hybrid origin ofMelocactus ¥ albicephalus ( Melocactus ernestii ¥ M. glaucescens ) in north-eastern Brazil Abstract Melocactus glaucescens (Cactaceae) is a critically endangered species endemic to northeastern Brazil. It grows in sympatry with other congeneric species and there is evidence for hybridization among them. We evaluated the levels of genetic and morphological variability and their substructuring between populations of M. glaucescens and sympatric species, and we tested for the occurrence of natural hybridization. Genetic variability was investigated using 12 allozyme loci, and morphological variability was investigated using multivariate morphometric analyses of 18 vegetative characters in nine natural populations of M. glaucescens , Melocactus ernestii , Melocactus concinnus and two distinct morphs of putative hybrids ( Melocactus ¥ albicephalus ). Genetic variability was low in all populations ( P = 7.7-41.7, A = 0.3-1.7, H e = 0.009-0.096), and all taxa displayed a deficit in heterozygotes. Low genetic structuring and moderate morphological structuring were found for M. glaucescens ( F ST = 0.045, A MRPP = 0.16) and M. concinnus ( F ST = 0.022, A MRPP = 0.11). The results obtained are inconclusive with respect to confirming the hypothesis of occurrence of hybridization because of an absence of diagnostic loci in the presumed parental species. The presence of several private alleles and the absence of linkage disequilibrium in the putative hybrids indicate that M. albicephalus should be treated as a distinct species, and not given hybrid status as recently stated by a number of authors. The large number of exclusive alleles and the levels of morphological structuring in the populations of M. glaucescens are important factors that need to be considered in the definition of strategies for the conservation of this species.

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