The infraspecific taxonomy of wild Anacardium occidentale is little studied. We investigated whether wild populations on coastal dunes in Piauí, Brazil differed from non‐wild populations. Ten populations were sampled and twenty one morphological variables were measured. Variation within and between populations was investigated with univariate and multivariate statistics. Dune populations were mostly more similar to one another than to domesticated ones. There was significant correlation between inter‐population geographical distance and morphological dissimilarity. Classification methods showed 96.4% successful assignment to the dune category and 86% to 100% to dune populations individually, but dune and non‐dune populations overlap morphologically. Dune populations had shorter, broader leaves, shorter drupes and fewer secondary veins. Non‐dune coastal populations showed strongest similarity to dune populations. Populations distant from the coast were most divergent. The population from the cerrado region was most distinct, with thicker leaf blades and narrower petioles. The dune populations are recognised as the “restinga ecotype” of A. occidentale. Correlation of dissimilarity and distance may result from gene flow and/or non‐inherited environmental effects. Ecology and nomenclature (including the vernacular “cajuí”) of the restinga ecotype are reviewed. Further comparison of restinga populations is needed along the Brazilian coastline and with natural cerrado populations.
Phytosociological analysis was used to quantify the structure of a disturbed mangrove next to a tidal creek of the Rio Igaraçu, Piauí, northeast Brazil, and comparison was made with a survey made fourteen years earlier. Thirty 10×10 m plots were demarcated in three areas of ten plots each. Height and circumference of trees of circumference at breast height ≥ 15 cm were measured in 285 individuals of Avicennia germinans (L.) L., Laguncularia racemosa (L.) C.F.Gaertn. and Rhizophora mangle L. Height ranged from 1.5−15 m (mean 4.4 m) and diameter from 4.8−28.7 cm (mean 7.2 cm). Avicennia and Laguncularia showed the highest parameter values (importance values 52% and 44%, respectively). Furthest from the creek and subject to less frequent tidal flooding, only Avicennia occurred, shorter (mean height 3.8 m) and fewer (density 130 ind ha−1) than elsewhere. In the central area (density 1240 ind ha−1) Avicennia dominated Laguncularia (importance values 53% vs. 47%). All species occurred nearest the creek (density 1480 ind ha−1, importance values Laguncularia 47%, Avicennia 46%, Rhizophora 7%), and heights and diameters were lower. Changes from a previous study suggest selective logging of larger individuals nearer the creek, especially Rhizophora, favouring regeneration of Laguncularia.
The diagnostic value of leaf shape for mangrove species Avicennia germinans and A. schaueriana was examined in four areas within the Rio Parnaíba delta, Maranhão, Brazil. Elliptic Fourier analysis of 627 leaves, followed by principal component analysis, provided shape and size data; the first seven principal component shape variables expressed 99.2% total variation. Discrimination between twelve combinations of species, location and disturbance levels was studied using k‐nearest‐neighbour classification. The species differed significantly in leaf shape but determination was reliable only in the tallest undisturbed forest (germinans narrowly elliptic or ovate, base acute, apex acute to acuminate; schaueriana broadly obovate, base attenuate, apex rounded). Symmetric variables (PC1 and PC3, 84.5% total variation) showed strongest differences. Predominant variation between species was in relative width and base shape (PC1), and within species in ovateness (PC3) between conserved and regenerating areas. Leaves were significantly smaller in A. schaueriana. Vernacular taxa siriba branca and siriba preta were inconsistent with taxonomic species but often significantly different in leaf shape. Avicennia germinans varied more under different geographical and ecological conditions. Shape‐size correlation needs further allometric study. Species delimitation needs morphometric study of a broader character range. Vernacular taxa recognition should be studied with ethnobiological techniques.
Marine angiosperms are submerged marine plants with a wide global distribution, occurring in temperate and tropical areas where they form meadows that harbour algae and marine fauna that are important for the functioning of the coastal ecosystem. This study is a floristic survey of the seagrasses occurring in the coastal region of the State of Piauí, Brazil. Five species were recorded for two genera in two families; for the Cymodoceaceae: Halodule wrightii Asch., Halodule beaudettei (Hartog) Hartog and Halodule emarginata Hartog; and for the Hydrocharitaceae: Halophila decipiens Ostenf. and Halophila baillonis Asch. ex Dickie. Species descriptions, an identification key, and information on geographic distributions and habitats of the five taxa are presented. All species are native but only Halodule emarginata is endemic to Brazil, and is reported here as a new record for Piauí, extending its range northwest from the coast of the neighbouring state of Ceará.
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