DOI: 10.5091/plecevo.146274

Authors: Piero G. Delprete, Jomar G. Jardim

Abstract: Background and aims – Single-stemmed plants 20–100 cm tall, with sessile or subsessile leaves in terminal rosettes gathering leaf litter, and axillary, 1–3-flowered inflorescence, from the state of Rio de Janeiro, southern Brazil, and from French Guiana, have traditionally been identified as Faramea tinguana. The disjunction of more than 3,200 km air distance between French Guiana and Rio de Janeiro stimulated an in-depth analysis of the specimens from those regions to evaluate if any morphological character might distinguish them. Material and methods – This study is based on examinations of herbarium specimens, material preserved in 60% ethanol, and field observations. Herbarium specimens were studied either on site or through loans from the CAY, CEPEC, G, G-DC, K, L, MO, NY, P, RB, U herbaria. Digital images of herbarium specimens were analysed through virtual herbaria. Traditional practices of herbarium taxonomy have been applied. A preliminary conservation status assessment of each species studied was made using the IUCN Red List Categories and Criteria. Results – The names F. tinguana and F. megalophylla are here lectotypified, and are treated as synonymous. Numerous reproductive characters support a clear distinction between the specimens from Rio de Janeiro and those from French Guiana traditionally identified as F. tinguana. Hence, the two distant populations are here treated as two distinct species. Faramea humicapiens, endemic to French Guiana, is newly described, and F. tinguana is restricted to the state of Rio de Janeiro. Faramea humicapiens is evaluated as Vulnerable and F. tinguana as Critically Endangered. A discussion on Neotropical litter-gathering Rubiaceae is also presented.

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DOI: 10.5091/plecevo.90936

Authors: Olivier Lachenaud, Piero G. Delprete

Abstract: Background and aims – The genus Carapichea (Rubiaceae), recently resurrected and separated from Psychotria, currently includes 24 Neotropical species and is morphologically heterogeneous. A revision of the genus in the Guianas is presented here, as part of the authors’ work on the Rubiaceae treatment in the Flora of the Guianas series. Material and methods – This paper is based on a study of herbarium specimens from BBS, BM, BR, BRB, CAY, INPA, K, P, P-JJR, and U; type specimens from other herbaria were consulted online. Some of the species were also studied in the field by the authors. Normal practices of herbarium taxonomy have been applied. Results – Three species previously included in Carapichea (C. altsonii, C. nivea, and C. sandwithiana) show aberrant characters for the genus and are transferred to Notopleura; new combinations are published for the former two (N. altsonii and N. nivea). Eight species of Carapichea, one of them still imperfectly known, are recorded from the Guianas; a ninth species, C. araguariensis, is included in this revision as it is expected to occur in the region. New combinations are published for two species: Carapichea galbaoensis and C. squamelligera, based on Psychotria galbaoensis and P. squamelligera, respectively; the former species was previously included in synonymy of C. guianensis, which is here redefined in a narrower sense. The delimitation of C. ligularis is expanded to include C. pacimonica as a synonym. The first records of C. adinantha in French Guiana – and the Guiana Shield – are documented. The taxonomy of the two remaining species, C. tillettii and C. urniformis, is left unchanged. For every species a complete description is presented, as well as data on distribution, ecology, phenology, local names (when known), and a list of collections studied.

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DOI: 10.5091/plecevo.2020.1565

Authors: Myriam Heuertz, Henri Caron, Caroline Scotti-Saintagne, Pascal Pétronelli, Julien Engel, Niklas Tysklind, Sana Miloudi, Fernanda Gaiotto, Jérôme Chave, Jean-François Molino, Daniel Sabatier, João Loureiro, Katharina Budde

Abstract: Background and aims – The evolutionary history of Amazonia’s hyperabundant tropical tree species, also known as “hyperdominant” species, remains poorly investigated. We assessed whether the hyperdominant Eschweilera coriacea (DC.) S.A.Mori (Lecythidaceae) represents a single genetically cohesive species, and how its genetic constitution relates to other species from the same clade with which it occurs sympatrically in French Guiana.Methods – We sampled 152 individuals in nine forest sites in French Guiana, representing 11 species of the genus Eschweilera all belonging to the Parvifolia clade, with emphasis on E. coriacea. Samples were genotyped at four simple sequence repeat (SSR) markers. We delimited gene pools, i.e., genetically coherent putative taxa, using STRUCTURE software and principal component analysis. We compared the genetic assignment of individuals with their morphological species determination and estimated genetic diversity and differentiation for gene pools and species. We also estimated genome size using flow cytometry.Key results – SSR profiles commonly displayed up to four alleles per genotype, suggesting that the investigated Eschweilera species bear a paleopolyploid signature. Flow cytometry suggested that the studied species are diploid with haploid genome sizes of 871–1046 Mbp. We detected five gene pools and observed a good correspondence between morphological and genetic delimitation for Eschweilera sagotiana Miers and the undescribed morphospecies E. sp. 3 (which resembles E. grandiflora (Aubl.) Sandwith), and to a lesser extent for E. decolorans Sandwith and E. micrantha (O.Berg) Miers. Eschweilera coriacea was the most genetically diverse species and included individuals assigned to each gene pool. Conclusions – We found no conclusive evidence for cryptic species within E. coriacea in French Guiana. SSRs detected fewer gene pools than expected based on morphology in the Parvifolia clade but discriminated evolutionary relationships better than available plastid markers. A positive trend between demographic abundance of species and allelic richness illustrates that hyperdominants may have a high evolutionary potential. This hypothesis can be tested using more powerful genomic data in combination with tree phenotypic trait variation and characterization of niche breadth, to enhance our understanding of the causes of hyperdominance in Amazonian trees.

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