Resumo Convolvulaceae é uma família predominantemente tropical e compreende entre 1600 e 1700 espécies. O Brasil é um importante centro de endemismo do grupo, mas sua diversidade ainda é pouco conhecida e subestimada no país. A flora de Convolvulaceae da Usina São José, aqui apresentada, portanto, incrementa o conhecimento sobre a diversidade da família no Nordeste. Foram registradas doze espécies e cinco gêneros de Convolvulaceae na região: Bonamia maripoides, Evolvulus nummularius, Ipomoea bahiensis, I. hederifolia, I. nil, I. philomega, I. quamoclit, I. tiliacea, Jacquemontia glaucescens, J. sphaerostigma, Merremia macrocalyx e M. umbellata. O tratamento conta com chave de identificação, descrições, ilustrações e comentários para os táxons.

Background and aims The extent to which genome size and chromosome numbers evolve in concert is little understood, particularly after polyploidy (whole-genome duplication), when a genome returns to a diploid-like condition (diploidisation). We study this phenomenon in 46 species of allotetraploid Nicotiana section Suaveolentes (Solanaceae), which formed less than six million years ago and radiated in the arid centre of Australia. Methods We analysed newly assessed genome sizes and chromosome numbers within the context of a restriction site-associated nuclear DNA (RADseq) phylogenetic framework. Key results RADseq generated a well-supported phylogenetic tree, in which multiple accessions from each species formed unique genetic clusters. Chromosome numbers and genome sizes vary from n = 2x = 15-24 and 2.7-5.8 pg/1 C nucleus, respectively. Decreases in both genome size and chromosome number occur, although neither consistently nor in parallel. Species with the lowest chromosome numbers (n = 15–18) do not possess the smallest genome sizes, and although N. heterantha has retained the ancestral chromosome complement, n = 2x = 24, it nonetheless has the smallest genome size, even smaller than that of the modern representatives of ancestral diploids. Conclusions The results indicate that decreases in genome size and chromosome number occur in parallel down to a chromosome number threshold, n = 20, below which genome size increases, a phenomenon potentially explained by decreasing rates of recombination over fewer chromosomes. We hypothesize that, more generally in plants, major decreases in genome size post-polyploidization take place while chromosome numbers are still high because in these stages elimination of retrotransposons and other repetitive elements is more efficient. Once such major genome size change has been accomplished, then dysploid chromosome reductions take place to reorganize these smaller genomes, producing species with small genomes and low chromosome numbers such as those observed in many annual angiosperms, including Arabidopsis.

Tipifi cação polínica em Leguminosae de uma área prioritária para conservação da Caatinga: Caesalpinioideae e Papilionoideae ABSTRACT(Pollen typifi cation of Leguminosae from a priority area for conservation of Caatinga: Caesalpinioideae and Papilionoideae). Th e municipality of Mirandiba, in Pernambuco, is considered a priority area for conservation of Caatinga and has a diverse fl ora. In this region, the family with the greatest number of species is the Leguminosae, which is represented by about 25% of the species known from the Caatinga. In this study we characterized the pollen grains of the subfamilies Caesalpinioideae and Papilionoideae, and established groups based on pollen morphology. Diff erences found within the Caesalpinioideae are discussed, especially exine ornamentation, which is striking between the different genera. In Papilionoideae, the most conspicuous diff erence was the type of aperture, where pores, colpores, and colpi were observed. In the two subfamilies, most genera are considered stenopalynous, making it diffi cult recognize species by only morphometric characters.

RESUMO -(Diversidade polínica das Mimosoideae (Leguminosae) ocorrentes em uma área de caatinga, Pernambuco, Brasil). O município de Mirandiba, Pernambuco, considerado prioritário para a conservação da caatinga, apresenta cerca de 25% das espécies de Leguminosae do bioma, sendo 23 espécies em 13 gêneros da subfamília Mimosoideae, das quais 6 espécies são endêmicas. Dezenove táxons desta subfamília tiveram seus grãos de pólen caracterizados por microscopia óptica e eletrônica de varredura, ilustrados e incluídos em uma chave de identifi cação. A morfologia polínica dos táxons estudados é muito variada, principalmente em relação às unidades de dispersão, sendo encontradas desde mônades, em Neptunia e Desmanthus; políades com oito grãos de pólen, uniplanar em Calliandra depauperata e multiplanar em Mimosa spp. e Pityrocarpa moniliformis, políades com 16 grãos de pólen, em Anadenanthera, Inga, Parapiptadenia, Pithecellobium e Senegalia, tétrades também em espécies de Mimosa, e políades amorfas com 32 grãos de pólen, presentes em Chloroleucon e Pithecellobium. Essas diferenças aliadas a caracteres morfométricos e da ectexina possibilitam a identifi cação da maioria dos táxons de Mimosoideae de Mirandiba. Palavras-chave: Leguminosae, Mimosoideae, caatinga, políade, tétrade ABSTRACT -(Pollen diversity of Mimosoideae taxa (Leguminosae) from a caatinga region, Pernambuco, Brazil). Mirandiba municipality in Pernambuco, is a prioritary conservation area for caatinga. It has almost 25% of Leguminosae species from the caatinga, where 23 species in 13 genera belong to the Mimosoideae subfamily and 6 species are endemics. The pollen grains of 19 mimosoid taxa were characterized by their pollen grains using light and scanning electron microscopy. All taxa are illustrated and keyed. Pollen morphology of these taxa is varied, mainly regarding pollen units; we found monads in Neptunia and Desmanthus; 8-grain uniplanar polyads in Calliandra depauperata and multiplanar ones in Mimosa spp. and Pityrocarpa moniliformis, tetrads also in Mimosa, polyads with 16 pollen grains in Anadenanthera, Inga, Parapiptadenia, Pithecellobium and Senegalia, and polyads with 32 pollen grains in Chloroleucon and Pithecellobium. Different pollen units allied to other morphometric and ectexine characters were useful to identify most mimosoid taxa from Mirandiba.

No abstract