Central Amazonas Research Articles

Pennsylvanian mixed siliciclastic-carbonate deposits of the Amazonas basin, North of Brazil: The record of an epicontinental sea in Western Gondwana

Epicontinental seas dominated the central Amazonas Basin during the late Carboniferous configuring singular paleogeography of West Gondwana connected to the Panthalassa Ocean. The Pennsylvanian record is represented by 1,7 km-thick mixed siliciclastic-carbonate-evaporite deposits forming a complete transgressive-regressive megacycle in the Amazonas Basin. Outcrop and core-based stratigraphic and facies analysis carried out in 50 m-thick mixed siliciclastic-carbonate transgressive succession of the Amazonas Basin identified twenty-six facies and microfacies, representative of coastal to platform depositional systems and grouped in three facies associations: (1) coastal aeolian deposits, consisting of fine to medium-grained sandstone, lime mudstone and finely-crystalline dolostone that correspond to a complex association of aeolian dunes, sand sheets, interdunes, fluvial channels and lagoon deposits bioturbated by Palaeophycus, Lockeia, Thalassinoides, Roselia, and meniscate trace fossils; (2) a mixed tidal flat setting, constituted by fine to medium-grained sandstone, mudstone, shale, siltstone and limestone interpreted as supratidal, tidal channel, tidal delta and lagoon settings with evidence of subaerial exposure; and (3) carbonate epicontinental platform deposits, consisting of lime mudstone, wackestone, packstone and grainstone with allochemicals (ooids and peloids), terrigenous grains and abundant, diversified open shallow marine benthic and nektonic organisms,. A Bashkirian age is suggested based on the presence of the Neognathodus symmetricus, Streptognathodus sp., and Ellisonia sp. These mixed siliciclastic-carbonate deposits are correlated with several successions in the west and east Amazonia and sub-Andean basins in South America. These records indicate that the Itaituba deposits constitute a significant portion of a vast Pennsylvanian epicontinental sea connected to the west with the Panthalassa Ocean.

Cardiac Evaluation in the Acute Phase of Chagas' Disease with Post-Treatment Evolution in Patients Attended in the State of Amazonas, Brazil.

BackgroundIn the past two decades, a new epidemiological profile of Chagas' disease (CD) has been registered in the Brazilian Amazon where oral transmission has been indicated as responsible for the increase of acute cases. In the Amazonas state, five outbreaks of acute CD have been registered since 2004. The cardiac manifestations in these cases may be characterized by diffuse myocarditis, with alteration in the electrocardiogram (ECG) and transthoracic echocardiogram (TTE).ObjectiveTo perform a cardiac evaluation in autochthonous patients in the acute phase and at least one year after submitted to treatment for acute CD and evaluate the demographic variables associated with the presence of cardiac alterations.MethodsWe evaluated patients diagnosed with acute CD through direct parasitological or serological (IgM) methods from 2007 to 2015. These patients were treated with benznidazole and underwent ECG and TTE before and after treatment. We assumed a confidence interval of 95% (CI 95%, p < 0.05) for all variables analyzed.ResultsWe observed 63 cases of an acute CD in which oral transmission corresponded to 75%. Cardiac alterations were found in 33% of the cases, with a greater frequency of ventricular repolarization alteration (13%), followed by pericardial effusion (10%) and right bundle branch block and left anterior fascicular block (2%). The follow-up occurred in 48 patients with ECG and 25 with TTE for a mean period of 15.5 ± 4.1 months after treatment. Of these, 8% presented normalization of the cardiac alterations in ECG, 62.5% remained with the normal exams. All of the patients presented normal results in TTE in the post-treatment period. As for the demographic variables, isolated cases presented more cardiac alterations than outbreaks (p = 0.044) as well as cases from Central Amazonas mesoregion (p = 0.020).ConclusionsAlthough cardiac alterations have not been frequent in most of the studied population, a continuous evaluation of the clinical-epidemiological dynamics of the disease in the region is necessary in order to establish preventive measures.

First record of non-native hybrid catfish Pseudoplatystoma reticulatum× Leiarius marmoratus in the Upper Paraná River basin, Brazil.

The aim of this study is to report the presence of a three non-native hybrid long-whiskered catfishes (family Pimelodidae) in the Upper Paraná River basin, Brazil. Genetic analyses demonstrated that the three presumptive hybrids were a result of the crossbreeding of Pseudoplatystoma reticulatum (central Amazonas River basin and Lower Paraná River) and Leiarius marmoratus (Amazonas, Essequibo and Orinoco rivers), producing a hybrid commonly known in Brazil as cachandiá. The potential threat to biodiversity, due to possible genetic contamination, competition and predation of wild stocks, of such artificially produced hybrid fishes is discussed.

A remarkable new Veturius (Veturius) of the Brazilian Central Amazonas, with an inventory of the genus in Brazil (Coleoptera: Passalidae)

SummaryA new species of Veturius (Veturius) Kaup, of Brazil, Central Amazonas, lower basin of Urucu, Tefé and Coari, is described and illustrated. V. urucuensis n. sp. belongs to the “cephalotes” species group, and has an external autapomorphy for the family Passalidae: a large tuft of setae on the medioposterior area of the metasternum. The species is closely allied to V. jolyi Boucher, 2006, from the Brazil-Venezuela-Guyana border. The peculiar endemism of the new species suggests an intra-continental island vicariance into the Amazon Basin. No similar process was known in the large genus Veturius. A complete inventory of the 22 Veturius species in Brazil is given, with their distribution, and following the previously established monophyletic species groups. From Brazil, two species are newly reported, V. (Ouayana) guyanensis Boucher, 2006 (Pará) and V. (O.) dominicae Boucher, 2006 (Roraima), and one species is confirmed, V. (O.) unicornis Gravely, 1918 (Amazonas). New details are given on some other Brazilian Veturius.

New sedimentological and palynological data from surface Miocene strata in the central Amazonas Basin areaNew sedimentological and palynological data from surface Miocene strata in the central Amazonas Basin area

The scarcity of stratigraphic data has hindered the demarcationof the outcropping area of Miocene deposits of the AmazonBasin, represented informally by the Novo Remanso Formation.Moreover, this unit is characterized by a sparse and irregular geographicdistribution due to its sedimentological features and rare fossilcontent. Miocene deposits cropping out in central Amazonas Basinarea were described in sedimentological terms and analyzed palynologically.All analyses were undertaken in samples collected at theUatumaRiver banks (Itapiranga and Sao Sebastiao do Uatuma cities).Lithostratigraphic data shows that Novo Remanso Formation consistsof sandstones, with subordinate conglomerates and pelites, characteristicof a meandering fluvial paleosystem, with fluvial channel, pointbar, floodplain and crevasse splay facies. The palynoflora retrieved fromfive samples consists exclusively of continental-origin palynomorphsdominated by angiosperms species. Trilete spores are well represented,while gymnosperms pollen grains are minor components. The presenceof Psilastephanoporites tesseroporus, Syncolporites poricostatus, Jandufouriaseamrogiformis and Polypodiaceoisporites potoniei ensure these depositsfits into the Grimsdalea magnaclavata palynozone (Regali et al.1974a, b), and the Grimsdalea magnaclavata/Crassoretitriletes vanraadshoovenipalynozones of Jaramillo et al. (2011) considered MiddleMiocene age. This age is confirmed by the zonation of Jaramillo et al.(2011), based on the LADs of Bombacacidites baumfalki (11.57Ma)and Crototricolpites annemariae (12.91Ma); and the FAD of Psilastephanoporitestesseroporus (14.00Ma). With these new data presentedherein, it is possible to assume that the Miocene strata represented bythe Novo Remanso Formation covers a larger area in the basin thanpreviously considered, and that it may be extended for about 300 kmuntil the Manacapuru village, indicating a Miocene subsidence phase.

New sedimentological and palynological data from surface Miocene strata in the central Amazonas Basin area

ABSTRACT The scarcity of stratigraphic data has hindered the demarcation of the outcropping area of Miocene deposits of the Amazon Basin, represented informally by the Novo Remanso Formation. Moreover, this unit is characterized by a sparse and irregular geographic distribution due to its sedimentological features and rare fossil content. Miocene deposits cropping out in central Amazonas Basin area were described in sedimentological terms and analyzed palynologically. All analyses were undertaken in samples collected at the Uatumã River banks (Itapiranga and São Sebastião do Uatumã cities). Lithostratigraphic data shows that Novo Remanso Formation consists of sandstones, with subordinate conglomerates and pelites, characteristic of a meandering fluvial paleosystem, with fluvial channel, point bar, floodplain and crevasse splay facies. The palynoflora retrieved from five samples consists exclusively of continental-origin palynomorphs dominated by angiosperms species. Trilete spores are well represented, while gymnosperms pollen grains are minor components. The presence of Psilastephanoporites tesseroporus, Syncolporites poricostatus, Jandufouria seamrogiformis and Polypodiaceoisporites potoniei ensure these deposits fits into the Grimsdalea magnaclavata palynozone (Regali et al. 1974a, b), and the Grimsdalea magnaclavata/Crassoretitriletes vanraadshooveni palynozones of Jaramillo et al. (2011) considered Middle Miocene age. This age is confirmed by the zonation of Jaramillo et al. (2011), based on the LADs of Bombacacidites baumfalki (11.57Ma) and Crototricolpites annemariae (12.91Ma); and the FAD of Psilastephanoporites tesseroporus (14.00Ma). With these new data presented herein, it is possible to assume that the Miocene strata represented by the Novo Remanso Formation covers a larger area in the basin than previously considered, and that it may be extended for about 300 km until the Manacapuru village, indicating a Miocene subsidence phase.

The Meeting of Waters, a possible shelter of evolutionary significant units for Amazonian fish

Identification of priority conservation areas is crucial for safeguarding freshwater ecosystems. Occurrence of unique populations and/or evolutionary significant units for key species is one of the most frequent reasons for protecting a region or location. In this study we have studied two of the most important fisheries resources of the Amazon basin, Curimata and Tambaqui, from different areas, in order to identify common zones of special diversity. Employing the Barcoding cytochrome oxidase I gene as a genetic tool, we have detected a clear differentiation of the populations inhabiting the Meeting of Waters and the rest of the basin for both species. This area corresponds to the confluence of the Solimoes and the Negro rivers, of different physicochemical water characteristics, at the Brazilian city of Manaus in central Amazonas. The Meeting of Waters area (near Manaus) could be recommended as a potential area subject of special management, given its apparent role as a shelter for evolutionary significant units.

A Revision of Selected Clades of Neotropical Mite Harvestmen (Arachnida, Opiliones, Cyphophthalmi, Neogoveidae) with the Description of Eight New Species

Among the least-studied families of mite harvestmen (Opiliones, Cyphophthalmi) is the family Neogoveidae, a group of arachnids that inhabits tropical rain forests on both sides of the Atlantic Ocean around the Equator, and an exquisite example of Gondwanan vicariance. To evaluate the diversity within Neogoveidae we studied the morphology of all currently recognized genera using a recent phylogeny of the group to provide a framework for the family in the Neotropics. That study identifies several clades that correspond to the recognized genera Neogovea, Huitaca, Metagovea, Canga, and the recently resurrected genus Brasilogovea, formerly synonymized with Neogovea. Neogovea is restricted to eastern Amazonia (Brazil, Guyana, French Guiana, Suriname), Huitaca remains endemic to Colombia, Canga is restricted to its type locality in the Serra de Carajás (Pará State, Brazil), Brasilogovea to Central Amazonas and the Tepuis region in Colombia, and Metagovea is the most widespread genus, found along the northern Andes from Perú to Venezuela, and extending to the Amazon region. All Neotropical genera are diagnosed and discussed. The formerly monotypic Huitaca is revised with the description of six additional species, all found in the high-altitude Colombian mountain areas called cordilleras, between 2,030 and 3,050 m. These include: Huitaca bitaco new species, Huitaca boyacaensis new species, Huitaca caldas new species, Huitaca depressa new species, Huitaca sharkeyi new species, and Huitaca tama new species, all from Colombia. Two additional species, Brasilogovea chiribiqueta new species, from Colombia, and Neogovea hormigai new species, from Guyana, are also described.

On the presence of Scinax pedromedinae (Henle, 1991) (Amphibia: Anura: Hylidae) in Amazonian Brazil and northern Peru

We report the presence of Scinax pedromedinae in northern Peru, near the point where the borders of Peru, Brazil, and Colombia meet (660 km northeast of Pucallpa and 900 km N of Puerto Maldonado), and in the Estação Ecológica Mamirauá in central Amazonas State, Brazil (1,200 km NE of Pucallpa, 1,100 km NNE of Puerto Maldonado, and 600 km E of the northern Peruvian locality reported here). These new records suggest a continuous distribution of this species in the western Amazon Basin, in eastern Peru, western Brazil, and northern Bolivia.

Description of the larva of Bromeliagrion rehni (Odonata: Coenagrionidae) with bionomic notes concerning its phytotelmic habitat in central Amazonas, Brazil

The last-stage larva of Bromeliagrion rehni Garrison in De Marmels &amp; Garrison, 2005 is described and illustrated and bionomics and habitat information on this species are provided. The study was conducted in the Reserva Florestal Adolpho Ducke, located near Manaus, state of Amazonas, Brazil.Twelve samplings were done between April, 2003 and April, 2005: six in the rainy season and six in the dry season. In each sampling month, 12 bromeliads (Guzmania brasiliensis Ule, 1907, Bromeliaceae) were collected, six of which were terrestrial and six epiphytic, yielding144 samples. A total of 75 specimens of B. rehni were collected. The relationship between larval B. rehni abundance and the measured environmental parameters (volume (ml), pH, season and stratum) was significant (ANCOVA, F = 5.296, d.f. = 130, p &lt; 0.001). Larvae were most abundant in the rainy season (p &lt; 0.01) and water volume was positively related to the abundance of B. rehni. Larvae of B. rehni can be distinguished from those of B. fernandezianum (the only species in the genus with described larvae) by the number of setae in the prementum and by the color of the apical region of the femur. The association of this species with phytotelmata of G. brasiliensis is reported here for the first time.

Three new species of Swartzia (Leguminosae–Papilionoideae) from northern South America

Descriptions of three recently discovered species of the prominent Neotropical tree genus Swartzia are presented, together with revised identification keys and a discussion of the morphological characters that distinguish the new species from close relatives. The three new species are each known from several localities. S. canescens has a relatively broad distribution in lowland areas in French Guiana, eastern Suriname, and in the Brazilian states of Amapa and Para, north of the Amazon River. It belongs to series Racemosae and is a close relative of S. discocarpa. S. manausensis is known from central Amazonas, Brazil. It is a member of series Tounateae and occurs sympatrically with the closely related species S. tessmannii. Another new species, S. ramiflora, is endemic to northern portions of Amazonas state in Venezuela and is part of a taxonomically difficult species complex centred around S. panacoco. Unlike most of the other entities in the complex, S. ramiflora is quite distinct morphologically. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153, 343–355.

A New Species of Votomita (Melastomataceae) from Venezuela, with Thoughts on Ovule and Seed Number and Seed Size

A new species of Votomita from southern Venezuela is described, illustrated, and distinguished from its relatives on the basis of fruiting material; certain useful floral characters can also be determined from the specimen. The new species illustrates a general condition in subfamily Memecyleae, i.e., a relatively large number of ovules is produced yet only one or a few large seeds are formed. Ovule and seed numbers are discussed, seed volumes are calculated for Mouriri and Votomita, and possible explanations for the differences are explored. Votomita ventuarensis Morley, sp. nov. TYPE: Venezuela. Terr. Fed. Amazonas: Dept. Atabapo, bosques medios y bajos inundables en el rio Ventuari-Macabana, 4?15'N, 66?20'W, 140 msnm, Sep. 1989, Luz Delgado 594 (holotype, MO; isotype, PORT). Figure 1. Arbor usque 15 m alta; pagina inferior costae mediae anguste 2-alata ad angulos, minute puberula; cryptae stomatatae unaquaeque cavitatibus 1-5; epidermes folii sine pigmento; hypodermis absens; stamina monadelpha; ovarium 4-loculare ovulis 22-25 axillaribus; semen unicum, globosum. Tree to 15 m high, glabrous except for the leaf midrib; young twigs rounded. Petioles 4.5-6 mm long; blades 7.9-12.4 cm long, 4.1-6 cm wide, ovate-elliptic to elliptic, acute at base, abruptly acuminate at the apex with an acuminum 0.7-1 cm long; midrib low-rounded to plane or slightly grooved adaxially when dry, prominent abaxially, flat and winged on the edges, the undermidrib minutely puberulent with hairs 20-40 pm long; lateral nerves when dry faintly visible or invisible adaxially, faintly visible abaxially. Midrib xylem tubular; stomatal crypts 30-36 per mm2 near the margin to 54 near the midrib, with (1-)2-5 cavities each, 50-60 /m high; adaxial epidermis of uniform thickness, 29-31 /tm thick including the cuticle, mostly one cell thick, occasionally two, mucilage walls none, the cytoplasm unpigmented and clear till stained, the inner walls straight and parallel with the outer ones; cuticle thin; abaxial epidermis also unpigmented; hypodermis none; foliar sclereids all terminal on the veinlets, irregularly stellate, often with an irregular horizontal central body 1-4 times as long as wide. Peduncles 1 per side at leafless nodes of twigs 3-4 mm thick below the leaf zone, 10.5-14 mm long with 2 internodes, the lower 0.5-1 mm long, the upper 10-13 mm, 1-flowered; bracts deciduous before fruit formation; pedicels 12-13 mm long in fruit; ovary locules 4, placentation axile, ovules 4-11 per placenta, 22-25 in all; fruits yellow to orange, ellipsoid, crowned with the calyx, 17-18 mm long including calyx by 12-14 mm diam. when dry, 20-21 mm long by 13-16 mm when boiled, the fruiting calyx 6.4-6.7 mm diam., 3-3.3 mm deep, the lobes low-triangular, 0.8-1.2 mm high, 4-5.2 mm wide; seed 1, spheroid, 9.79.9 mm high, 8.8-9.6 mm thick, with an irregularly elliptic raised area (function unknown) ca. 4 mm from the broken chalazal strand, the raised area 6 mm long, 4 mm wide, 0.5-1 mm high, with edges that overhang 0-0.5 mm; the raised area presumably includes the micropyle. Petal scars on the fruit rounded-triangular, 2.3-2.7 mm wide, 0.9-1.2 mm long; stamen scars 8, the filament scars broad, thin, and united, forming a continuous ring 3.2-3.7 mm in outside diam., 0.2-0.5 mm thick, the stamens thus monadelphous; thecae adaxial on the filaments and placed low so that their bases leave imprints 0.9-1.2 mm wide, 0.8-1.0 mm thick radially around the style base, the total stamen thickness at base 1.0-1.3 mm. Distribution. Known only from the type locality east of San Fernando de Atabapo, northwest of central Amazonas, Venezuela. Local name. Cometure tierra firmero. Although the type specimen bears only ripe fruits, the filament scars and anther imprints on the fruits yield useful floral information, and with careful dissection of the 1-seeded fruit (when boiled) all or most of the undeveloped ovules can be found and the nature of the placentation determined, in spite of the compaction and distortion that have taken place. The new species is unique in the genus in its unpigmented epidermises. Further distinctions of this plant from the other species follow, starting NovoN 9: 241-244. 1999. This content downloaded from 40.77.167.42 on Wed, 30 Nov 2016 05:02:53 UTC All use subject to http://about.jstor.org/terms

Direct and indirect effects of predation on tadpole community structure in the Amazon rainforest

Abstract The relationship between the distribution of predators (fish, odonates and water beetles) and prey assemblages (amphibian larvae) was investigated in the tropical rainforest of central Amazonas, Brasil. The anuran community uses a variety of waterbodies for reproduction, ranging from streams and streamside ponds to isolated forest ponds. Predators in this system include fish in streams and streamside ponds, and invertebrates (primarily odonate naiads and beetles) in forest ponds. Tadpole species richness and assemblage structure were related to fish density and species richness. No relationships between tadpole assemblages and abiotic pond characteristics were detected. The presence offish explained much of the variation in both species composition and species richness within and among ponds. Some species of tadpole were consistently found to coexist with high densities of fish. Path analyses suggest that while fish have a strong direct effect on tadpole associations and species richness, they also have an indirect effect through invertebrate predators (odonate larvae and coleopteran beetles). Prey survival‐strategies such as palatability and behaviour may explain how tadpole species composition is affected by predators at the community level. These findings suggest that the observed patterns of habitat use by larval anurans may be structured in response to the distribution of key predators (fish) in this system.

Genetic studies on the Ticuna, an eniǵmatic tribe of Central Amazonas

The Ticuna are an Amerindian tribe of Central Amazonas, a key location in theories of the peopling of eastern South America. The results of typing some 1760 members of the tribe with respect to 37 different genetic systems are reported, as are the results of HLA typings on a subsample of 129 persons. Salient findings include the following. (1) Except for a high frequency of LMs allele and an unusual combination of HLA allele frequencies, there are no notable findings with respect to the commonly studied polymorphic systems. A multivariate treatment of six of the most commonly studied genetic polymorphisms accords the Ticuna an 'average' position among Amerindian tribes. (2) There is much less intervillage heterogenicity than usually encountered in Amerindian tribes; this is attributed to recent high rates of intervillage migration due to religious developments. (3) A thus-far unique polymorphism of ACP1 was identified, the responsible allele having a frequency of 0.111. (4) In proportion to the size of the tribe, there was a relative paucity of 'private' genetic variants, the ACP1 allele being the only one. This discrepancy is attributed to a relatively recent numerical expansion of the tribe; effective population size over the past several thousand years is thought to have been well below what present numbers would suggest. (5) The thesis is again advanced that 'private variants' (alleles not occurring as polymorphisms of wide distribution) are more common in Amerindian than in Caucasian or Japanese populations.

Archaeological Research on the Central Amazonas. A Contribution to the Early History of the South-American Lowlands

Archaeological Research on the Central Amazonas. A Contribution to the Early History of the South-American Lowlands