Neotropical Entomology 35(5): 579-587 (2006)

Several alternative interpretations of the pollen records of lake sediments in the Amazonia may arise due to a lack of understanding of the modern environments, mainly related to pollen–vegetation relationship. Therefore, in this work, we studied the modern pollen rain in sediments of the Amendoim Lake, plateaus of the Serra Sul dos Carajás, southeastern Amazonia. This study indicates the predominance of pollen grains from forest formation (ombrophilous forests and capão florestal) over montane savanna in the lake sediments, despite the fact that montane savanna occupies ~90% of the drainage basin. Additionally, these sediments reflect stronger signal of pollen from ombrophilous forests that occur in the slopes of the plateau. Important components of montane savanna such as Vellozia and Cereus were not observed in the modern pollen rain, which may be related to their shorter flowering periods restricted to the beginning of wetter conditions. The absence of Sacoglottis, Trichilia, Clusia, Emmotum, Guapira and Simarouba in the pollen rain is likely associated with different pollination strategy. The occurrence of windblown pollen of Alchornea, Pseudolmedia, Ilex and Cecropia, which are found from low to highlands of the Carajás region, reinforces a regional vegetation signal in sediments. Several plants from the studied site have been improperly described, according to taxonomy and ecology. For example, the current occurrence of Ilex and Styrax in the study site clearly suggests that they cannot be used as indicators of colder palaeoclimate conditions, as previously described. In addition, Poaceae can be found in drier to wetter substrate conditions, and abundance of their pollen grains in lakes can significantly vary according to relief morphology and cannot indicate palaeovegetation openness. Therefore, this work is a good background for further palaeobotany studies for this region.

No abstract

The oils of three samples of the leaves and fine stems of Myrcia bracteata, M. cuprea and M. sylvatica were obtained by hydrodistillation and analysed by GC-MS. The main compounds found in the oils of M. bracteata were (E)-nerolidol (80.8%) for the sample B-1; (E)-β-farnesene (33.9%) for the sample B-2; and spathulenol (31.0%) for the sample B-3. The oils of M. cuprea were dominated by myrcene (48.1%) and β-caryophyllene (19.9%) in the sample C-1; by β-caryophyllene (39.1%), myrcene (19.2%) and α-pinene (15.9%) in the sample C-2; and by β-caryophyllene (38.1%), germacrene D (21.8%) and germacrene B (19.5%) in the sample C-3. The major constituents identified in the oils of M. sylvatica were selin-11-en-4-α-ol (24.7%), caryophyllene oxide (16.6%) and spathulenol (13.8%) in the sample S-1; by cis-calamenene (30.1%) and spathulenol (18.7%) in the sample S-2; and by spathulenol (40.2%) and β-bisabolene (14.7%) in the sample S-3.

The essential oils of Guatteria juruensis, G. microcalyx, G. poeppigiana and Guatteriopsis blepharophylla were obtained by hydrodistillation and analysed by GC and GC/MS. The main compounds found in the leaf oil of Guatteria juruensis were spathulenol (77.5%) and α α α α α-pinene (4.5%). The leaf oil of Guatteria microcalyx was dominated by caryophyllene oxide (44.2%), α α α α α-pinene (11.9%) and β β β β β-pinene (6.3%). The major constituents identified in the leaf oil of Guatteria poeppigiana were spathulenol (53.0%), kushinol (10.9%) and humulene epoxide II (5.7%). The main volatiles found in the leaf oil of Guatteriopsis blepharophylla were caryophyllene oxide (51.0%), humulene epoxide II (6.8%) and 14-hydroxy-9-epi-(E)-caryophyllene (4.1%). The spathulenol and caryophyllene oxide could be considered as chemotaxonomic markers due their common occurrence in Xylopia, Guatteria and Duguetia species.

The leaf oils of Xylopia aromatica, X. cayennensis, X. emarginata and X. nitida were obtained by hydrodistillation and analysed by GC-MS. The main compounds found in the oil of X. aromatica were bicyclogermacrene (36.5%), spathulenol (20.5%) and limonene (4.6%). The oil from X. cayennensis was dominated by α α α α α-pinene (29.2%), β β β β β-pinene (16.5%), caryophyllene oxide (14.5%), bicyclogermacrene (14.5%), germacrene D (4.7%) and 1,8-cineole (4.5%). The major constituent identified in the oil of X. emarginata was spathulenol (73.0%). The main components found in the oil of X. nitida were γ γ γ γ γ -terpinene (44.1%), p-cymene (13.7%), α α α α α-terpinene (12.6%) and limonene (11.3%). Early papers indicated that spathulenol and caryophyllene oxide are also important volatile compounds found in the leaf oils of Xylopia, Duguetia and Guatteria species. At first sight they could be considered as chemotaxonomic markers to these Annonaceae genera.

No abstract

This paper contains data on the chemical composition of the essential oils of 22 leaf samples of Piper marginatum Jacq. collected in different areas and ecosystems of the brazilian Amazon, as well as an overview of the available literature. The species presents a large synonymy based on their different leaf characteristics and distinct scents where some of them smell like anise or very close compounds. By GC, GC/MS, and cluster analysis, we identified seven chemotypes for the leaf oils. The main components found in chemotype I were safrole (1) and 3,4-(methylenedioxy)propiophenone (2). The chemotype II was dominated by 3,4-(methylenedioxy)propiophenone (2) and p-mentha-1(7),8-diene (10). The major compounds identified in chemotype III were 3,4-(methylenedioxy)propiophenone (2), myristicin (3), (E)-beta-ocimene (11), and gamma-terpinene (12). In the chemotype IV, the principal constituents were beta-caryophyllene (13), alpha-copaene (14), and 3,4-(methylenedioxy)propiophenone (2). The chemotype V was dominated by (E)-isoosmorhizole (6), (E)-anethole (8), and isoosmorhizole (7). The main compounds found in the chemotype VI were 2-methoxy-4,5-(methylenedioxy)propiophenone (4), methoxy-4,5-(methylenedioxy)propiophenone isomer 5, and (E)-isoosmorhizole (6). The major constituents in chemotype VII were beta-caryophyllene (13), bicyclogermacrene (15), and (E)-asarone (9).