Seasonal stable isotope variations of the modern Amazonian freshwater bivalve Anodontites trapesialis

In a floodplain lake of the Amazon River near the city of Iquitos, northeastern Peru, a one-year monitoring experiment was conducted during which water samples and living bivalves (Anodontites trapesialis) were collected with the aim to investigate seasonal δ¹⁸O variation in and fractionation between bivalve aragonite and host water. Both host water and molluscan growth increments show more than 8‰ seasonal variation in δ¹⁸O. In the floodplain lake under study the δ¹⁸O variation of the water is controlled by contrasting dry and wet season evaporation-precipitation regimes. Molluscan δ¹⁸O appears to be in equilibrium with the host water. Although an approximately 4.0‰ offset occurs, δ¹³C records of water and bivalves are in good agreement, suggesting that both δ¹⁸O and δ¹³C of the shells of freshwater bivalve A. trapesialis are good recorders of (palaeo-)environmental conditions. The δ¹³C of Dissolved Inorganic Carbon (DIC) is governed by plant growth and/or by changes in aquatic chemistry, affecting the DIC pool.     

Calls,colours, shape,and genes: a multi‐trait approach to the study of geographic variation in the Amazonian frog Allobates femoralis

Evolutionary divergence in behavioural traits related to mating may represent the initial stage of speciation. Direct selective forces are usually invoked to explain divergence in mate‐recognition traits, often neglecting a role for neutral processes or concomitant differentiation in ecological traits. We adopted a multi‐trait approach to obtain a deeper understanding of the mechanisms behind allopatric divergence in the Amazonian frog, Allobates femoralis. We tested the null hypothesis that geographic distance between populations correlates with genetic and phenotypic divergence, and compared divergence between mate‐recognition (acoustic) and ecological (coloration, body‐shape) traits. We quantified geographic variation in 39 phenotypic traits and a mitochondrial DNA marker among 125 individuals representing eight populations. Geographic variation in acoustic traits was pronounced and tracked the spatial genetic variation, which appeared to be neutral. Thus, the evolution of acoustic traits tracked the shared history of the populations, which is unexpected for pan‐Amazonian taxa or for mate‐recognition traits. Divergence in coloration appeared uncorrelated with genetic distance, and might be partly attributed to local selective pressures, and perhaps to Batesian mimicry. Divergence in body‐shape traits was low. The results obtained depict a complex evolutionary scenario and emphasize the importance of considering multiple traits when disentangling the forces behind allopatric divergence. ©2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 826–838.     

A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin,with a discussion of historical biogeography of western Amazonas and Paraguay River basins

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.     

Integrated Middle Devonian chitinozoan and miospore zonation of the Amazonas Basin, northern Brazil

Middle Devonian chitinozoans were studied from 13 deep wells in the central part of the Amazonas Basin, northern Brazil, and compared with a newly established regional miospore zonation. Of the 23 chitinozoan species encountered, four are newly described: Ancyrochitina multibrachiata, Lagenochitina praeavelinoi, Ramochitina autasmirimense, and Ramochitina herculesi and seven species are retained in open nomenclature because of an insufficient number of well-preserved specimens. The stratigraphic intervals investigated herein correspond to three miospore interval range zones previously defined for the Amazonas Basin, namely, the Grandispora/Samarisporites spp. (GS); late Emsian-early Eifelian, Grandispora permulta (Per); late early Eifelian through the Eifelian-Givetian transition, and Geminospora lemurata-Chelinospora ex. gr. ligurata (LLi); early Givetian. A regional Middle Devonian chitinozoan biozonation, also consisting of three zones, is proposed for the investigated interval. These zones are the interval zone of Angochitina n. sp. A (early Eifelian), the interval zone of Alpenachitina eisenacki (late early to late Eifelian), and the total range zone of Ramochitina stiphrospinata (early Givetian).     

The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

Between 1983 and 1988 a total of 928 litter-filled baskets (1.8 1 volume), exposed for various periods on a stream litterbank and in its vicinity, collected 2703 individuals of 122 macrofaunal species, excluding chironomids. Species abundance was analysed in relation to exposure time, annual inundation cycle, water depth and sample size. Long-term, average species packing and animal density proved to be relatively invariant and revealed non-random frequency patterns. Previous and present data indicate that these patterns are a function of regular, specific life cycles and of intra-specific, stereotype behaviour in relation to space and litter quality, among other possibilities not considered here. Potential competition for space in these communities is discussed, considering the assumption of individual random movement versus species maintenance as a function of genetically and neurophysiologically in ormed, non-random behaviour.     

An Asiatic Chironomid in Brazil: morphology,DNA barcode and bionomics

In most freshwater ecosystems, aquatic insects are dominant in terms of diversity; however, there is a disproportionately low number of records of alien species when compared to other freshwater organisms. The Chironomidae is one aquatic insect family that includes some examples of alien species around the world. During a study on aquatic insects in Amazonas state (Brazil), we collected specimens of Chironomidae that are similar, at the morphological level, to Chironomus kiiensis Tokunaga and Chironomus striatipennis Kieffer, both with distributions restricted to Asia. The objectives of this study were to provide morphological information on this Chironomus population, to investigate its identity using DNA barcoding and, to provide bionomic information about this species. Chironomus DNA barcode data were obtained from GenBank and Barcode of Life Data Systems (BOLD) and, together with our data, were analyzed using the neighbor-joining method with 1000 bootstrap replicates and the genetic distances were estimated using the Kimura-2-parameter. At the morphological level, the Brazilian population cannot be distinguished either from Chironomus striatipennis or Chironomus kiiensis, configuring a species complex but, at the molecular level our studied population is placed in a clade together with Chironomus striatipennis, from South Korea. Bionomic characteristics of the Brazilian Chironomus population differ from the ones of Chironomus kiiensis from Japan, the only species in this species complex with bionomic information available. The Brazilian Chironomus population has a smaller size, the double of the number of eggs and inhabits oligotrophic water, in artificial container. In the molecular analysis, populations of Chironomus striatipennis and Chironomus kiiensis are placed in a clade, formed by two groups: Group A (which includes populations from both named species, from different Asiatic regions and our Brazilian population) and Group B (with populations of Chironomus kiiensis from Japan and South Korea). Genetic distance between the Brazilian population and specimens in Group A suggests that it was recently introduced in Brazil, and that its country of origin is probably South Korea.     

Trophic structure of macroinvertebrates in Amazonian streams impacted by anthropogenic siltation

This study assessed the results of anthropogenic sediment input on macroinvertebrate trophic structure in streams located in an area of oil and natural gas exploitation in Brazil's Amazon forest. The results indicate that macroinvertebrate communities both in streams impacted by anthropogenic sediments and in non‐impacted streams are composed mainly of taxa in the following functional feeding groups: predators, gathering‐collectors, scrapers, shredders and filtering‐collectors. The highest densities were observed for collector‐gatherers, followed by scrapers, predators, shredders and filtering‐collectors. However, both the richness and the density of all groups were reduced in impacted streams. The reductions were significantly related to suspended inorganic sediment load and to the colour of suspended sediments. The relative proportion of shredders in streams impacted by anthropogenic sediments was significantly reduced as compared with the proportion observed in non‐impacted streams. This resulted from lower availability of coarse particulate organic matter in these streams owing to burial of leaves and other plant material. These results indicate changes in the functioning and productivity of streams owing to anthropogenic siltation. This is because the benthic macroinvertebrate communities, sampled during this study, were dependent on the degradation of leaves, which are the primary energy source sustaining the benthic foodweb.     

Microfacies and sequence stratigraphy of the Amapá Formation, Late Paleocene to Early Eocene, Foz do Amazonas Basin, Brazil

On the basis of thin-section studies of cuttings and a core from two wells in the Amapá Formation of the Foz do Amazonas Basin, five main microfacies have been recognized within three stratigraphic sequences deposited during the Late Paleocene to Early Eocene. The facies are: 1) Ranikothalia grainstone to packstone facies; 2) ooidal grainstone to packstone facies; 3) larger foraminiferal and red algal grainstone to packstone facies; 4) Amphistegina and Helicostegina packstone facies; and 5) green algal and small benthic foraminiferal grainstone to packstone facies, divisible locally into a green algal and the miliolid foraminiferal subfacies and a green algal and small rotaliine foraminiferal subfacies. The lowermost sequence (S1) was deposited in the Late Paleocene–Early Eocene (biozone LF1, equivalent to P3–P6?) and includes rudaceous grainstones and packstones with large specimens of Ranikothalia bermudezi representative of the mid- and inner ramp. The intermediate and uppermost sequences (S2 and S3) display well-developed lowstand deposits formed at the end of the Late Paleocene (upper biozone LF1) and beginning of the Early Eocene (biozone LF2) on the inner ramp (larger foraminiferal and red algal grainstone to packstone facies), in lagoons (green algal and small benthic foraminiferal facies) and as shoals (ooidal facies) or banks (Amphistegina and Helicostegina facies). Depth and oceanic influence were the main controls on the distribution of these microfacies. Stratal stacking patterns evident within these sequences may well have been related to sea level changes postulated for the Late Paleocene and Early Eocene. During this time, the Amapá Formation was dominated by cyclic sedimentation on a gently sloping ramp. Environmental and ecological stress brought about by sea level change at the end of the biozone LF1 led to the extinction of the larger foraminifera (Ranikothalia bermudezi).     

A new species of Passiflora (Passifloraceae) from Amazonian Brazil

Passiflora cordistipula, a new species of subg.Passiflora, ser.Lobatae, from the state of Amazonas, Brazil, is described and illustrated.     

Matsigenka myth and morality: Notions of the social and the asocial

This paper explores Matsigenka notions of morality as evidenced in central mythological texts. The focus is on myth since, it is argued, myths provide a means whereby fundamental conditions of everyday life as conceptualized by their conventional audience can be understood and interpreted. Although myth does not provide a uniformly accepted cultural blueprint of social reality, a certain intersubjective consonance is to be expected. It is argued that to the Matsigenka morality is primarily a means to maintain conditions of conviviality. Matsigenka moral considerations are thus context‐dependent and can only be reflected upon casuistically.