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This study aims to expand knowledge of the pollen morphology of Passifloraceae and contribute to the taxonomic delimitation of the group by morphologically characterizing pollen grains of species that occur in the Brazilian state of Bahia. Thirty-six species occur in the state, one of the genus Mitostemma (M. glaziovii) and 35 of the genus Passiflora. Pollen samples were acetolysed, measured, and described using light and scanning electron microscopy. The results group the studied species into four pollen types based mainly on aperture type and number, opercular variation, and the presence/absence of ornamentation elements inside the lumina of the reticulum: Pollen type I - species belonging to the subgenera Astrophea and Deidamioides; pollen type II - subgenus Decaloba; pollen type III - subgenus Passiflora; and pollen type IV - M. glaziovii, with pollen characteristics that separate it from the other species analyzed. The results reinforce the recognition of three subgenera of Passiflora. Morphopalynologically the species have very similar pollen types except for those of the subgenus Deidamioides, which are quite diverse and thus included in another pollen type. The results reveal the importance of pollen grains for the taxonomic study of Passifloraceae.

Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests., Sistema de Informação sobre a Biodiversidade Brasileira, supporting the Flora do Brasil 2020 project; Programa de Apoio a Pesquisadores Emergentes da Universidade Federal da Bahia and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (process 23038.009148/2013-19, to D.C.); the Alexander von Humboldt Foundation and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (E-26/203.269/2016–JCNE and E-26/010.000990/2016–APq1, to M.T.); the National Science Foundation (Grant DEB-0316614, to S.K. and L.L.G. and Grant DEB- 0818399, to F.A.M. and R.G.); the British Council [Researcher Link 127407379 and the Royal Society of London (International Exchange IE140292, to T.S.)]; Fundação de Amparo à Pesquisa do Estado de São Paulo (2015/50488-5, to D.C. and L.P.d.Q); and the Natural Environment Research Council (NE/N012488/1; to T.S. and P.M.).

Uma nova espécie de Passifloraceae é descrita e ilustrada, Passiflora mucugeana T.S. Nunes & L.P. Queiroz. Esta espécie é conhecida até o momento, na região da Chapada Diamantina, Bahia, em áreas próximas aos municípios de Mucugê, Ibicoara e Barra da Estiva, em áreas de florestas estacionais e campo rupestre (Complexo Espinhaço), chegando a uma altitude de 1.200 metros. Passiflora mucugeana é inserida no subg. Passiflora supersect. Stipulata Feuillet & MacDougal sect. Granadillastrum Triana & Planch., por apresentar caracteres morfológicos que a assemelham a P. imbeana Sacco. A new Brazilian species of Passifloraceae is described and illustrated: P. mucugeana T.S. Nunes & L.P. Queiroz. This species is from the Chapada Diamantina region, state of Bahia, near the towns of Mucugê, Ibicoara and Barra da Estiva, growing in semideciduous forests and "campo rupestre", at 1200 m altitude. The new species is classified in subg. Passiflora supersect. Stipulata Feuillet & MacDougal sect. Granadillastrum Triana & Planch., because it appears to be a close relative of P. imbeana Sacco.