Eastern Bahia Research Articles

Rhyacian to Orosirian short-lived polyphase deformation and migmatization in northernmost São Francisco Craton, Brazil

The Minas-Bahia Orogen, which is Siderian-Orosirian age, is exposed in the northern sector of the São Francisco Craton and in its African counterpart, the Congo Craton. In this sector, two orogenic domains outcrops with geological evolution and terrains with different trends: Western and Eastern Bahia. The advance of scientific knowledge in the northeast of the West Bahia Orogenic Domain has revealed the existence of more tectonic terrains than those traditionally delimited, and reveal the presence of juvenile terranes and cratonic crust separated complex zones where they interacted. The region of interaction between the Gavião and Bom Jesus da Lapa Paleoplate has been the subject of debates about the tectonic significance of granulitic rocks with Meso-Neoarchean protoliths, which are intruded by Rhyacian - Orosirian granitoids. The set of geological data presented in this article demonstrates that the metatexite migmatites with felsic granulitic paleosome and charnockitic neosome were generated during the initial phases of the collision between these two paleoplates, between 2068 and 2058 Ma. The structural mass transport is from NW to SE. The youngest migmatization event, in high amphibolite facies, occurred during NNW-SSE trending sinistral strike-slip tectonics as suggested by the emplacement of Dn+3 neosomes controlled by S/C/C' structures, in between 2049–2000 Ma. The interpreted tectonic model is complex and involves the accretion and collision among Bom Jesus da Lapa, Gavião and Jequié paleoplates during the Rhyacian-Orosirian, contributing to the advancement of knowledge of tectonic pieces and their interactions that contributed to the formation of Columbia supercontinent.

Acoustic partitioning explains the coexistence between two Physalaemus species (Anura, Leptodactylidae) in the Atlantic Forest in Eastern Bahia State, Brazil

In this study we investigate the niche interaction between the frogs Physalameus cuvieri and Physalaemus kroyeri that occur in syntopy in water bodies of the Atlantic Forest located in the eastern Bahia State, Brazil. We investigated the niche width and overlap in the calling activity time, microhabitat use, diet composition, advertisement call, and body size. Both species preferred the same substrate and calling substrate categories, and showed low niche width values and high spatial niche overlap values. The pseudocommunity analysis revealed the absence of competition in space use. Ants and termites were the most important items in the diet of both species with the pseudocommunity analysis indicating an absence of competition in the diet. The two species demonstrate a greater similarity in body proportions and a high overlap in the calling activity time. However, they showed divergence in acoustic parameters, especially in the dominant frequency and call duration. Our results reinforce the role of advertisement call as a relevant attribute for anuran coexistence and highlight the importance of analyzing the various axes of the multidimensional niche for the most reliable description of the existence and magnitude of niche partitioning.

Dichorisandra rhizantha (Commelinaceae), a new morphologically unusual species from Bahia, Brazil

We describe, discuss, and illustrate Dichorisandra rhizantha, a new species from a transitional area between the Atlantic Forest and Caatinga domains in eastern Bahia state, Brazil. The species was assessed as Endangered, especially for its distribution restricted to forest fragments. The new species is morphologically similar to D. hirtella, D. radicalis and D. jardimii, but clearly differs from these by the inflorescence arising directly from the rhizome, and a pubescent indument on stem, leaves and sepals. We also present a distribution map of the species and taxonomic comments.

Spatial distribution of canine Leishmania infantum infection in a municipality with endemic human leishmaniasis in Eastern Bahia, Brazil.

Efforts to control a zoonotic disease such as visceral leishmaniasis (VL) caused by Leishmania infantum can be successful if they rely on comprehensive data on animal infection. In Bahia state, Brazil, human VL is endemic, yet some areas have no epidemiological data on canine L. infantum infection and canine leishmaniasis (CanL) to date. We aimed to perform an epidemiological study describing the spatial distribution and characterizing canine L. infantum infection in two districts of the municipality of Muritiba, where human cases have occurred. Brazilian official serodiagnostic protocol (ELISA and immunochromatographic tests), PCR and clinical examination were performed in 351 owned dogs. A seroprevalence of 15.7% (55/351) was found, and L. infantum identified in 88.8% (32/36) of PCR tested samples. Spatial distribution of positive dogs indicated infection in both urban and rural districts. There was no association between seropositivity and sex or breed, but dogs older than 2 years were 3.8 times more likely to be seropositive (95% CI 1.57 - 9.18) than younger dogs. Among seropositive dogs, 80% (44/55) had clinical manifestations of CanL: 75% (33/44) presented dermatopathy, 50% (22/44) emaciation, and 29.5% (13/44) ophthalmopathy. This is the first report on canine seroprevalence and natural L. infantum infection in Muritiba, Bahia.

Rhyacian-Orosirian isotopic records from the basement of the Araçuaí-Ribeira orogenic system (SE Brazil): Links in the Congo-São Francisco palaeocontinent

Assembled during the Rhyacian-Orosirian boundary, the Congo-São Francisco palaeocontinent remained linked by a continental bridge from ca. 2 Ga to the Atlantic Ocean opening in the Cretaceous. To the south of that bridge, precursor basins and orogenic outcomes encompassed by the Neoproterozoic-Cambrian Araçuaí-Ribeira orogenic system (AROS) and its African counterparts, developed. The AROS discloses reworked basement units, like the Juiz de Fora, Pocrane and Quirino complexes, which are key units to retrieve the Palaeoproterozoic history of the Congo-São Francisco palaeocontinent. This paper presents new U-Pb ages, and the first Lu-Hf in zircon signatures from those complexes. All magmatic zircon grains show Rhyacian and Orosirian ages, ranging from c. 2250 Ma to c. 1850 Ma. The best Concordia ages range from 2184 ± 9 Ma to 2080 ± 19 Ma. Hf in zircon and whole-rock Sm-Nd data disclose mantle-related signatures for both, the Pocrane and Juiz de Fora complexes, suggesting igneous protoliths with no or very few involvement of continental crust, similarly to juvenile magmatic arcs. Conversely, Hf in zircon data for the Quirino complex show an evolved signature compatible with a magmatic arc developed on a continental older crust with Archaean components. Together with a thorough compilation on Rhyacian-Orosirian orogenic systems (ROOS), our data allow us to envisage links within the Congo-São Francisco palaeocontinent, comprising orogens characterised by mostly evolved isotopic signatures and zircon inheritance. They are grouped into the: (i) W-ROOS, including the Mantiqueira complex, the west segment of the Eastern Bahia belt, intrusions in the south Gavião and Porteirinha blocks, and parts of the Mineiro belt; and (ii) E-ROOS, comprising the Quirino complex, basement rocks of the Cabo Frio tectonic domain, the coastal Eastern Bahia belt, and, in Africa, Eburnean and Kimezian complexes, as well as the western Angola shield. Assembled between the W-ROOS and E-ROOS, an orogenic system with prominent juvenile to moderately juvenile isotopic signature (JU-ROOS) includes the Juiz de Fora and Pocrane complexes, and the Buerarema complex at the central segment of the Eastern Bahia belt.

Aquatic and marsh plants from the Recôncavo basin of Bahia state, Brazil: checklist and life forms

Aquatic and marsh plants are those that have the capacity to withstand a continuous or periodic submersion in water, at least of their roots. Such plants are thus able to occupy environments that are at least periodically waterlogged. The knowledge about this plant group is still rather incomplete for various parts of Brazil including the Northeast. The present study was conducted in Bahia state, through collections in 20 municipalities within the Recôncavo basin between 2009 and 2015. All species were classified across six life forms. We report 316 species in 206 genera and 71 families, including 11 fern species, with helophytes and emergent being the commonest ones. Collection efforts in aquatic environments in the Recôncavo region added nine families of angiosperms to those already reported in previous studies of such plants in Northeastern Brazil. The region presents a wide variety of aquatic and marsh plants and the respective habitats play an important role in the conservation/maintenance of biodiversity and especially of water bodies in Eastern Bahia.

From evergreen to deciduous tropical forests: how energy–water balance, temperature, and space influence the tree species composition in a high diversity region

Background: Understanding floristic and geographic patterns in one of the most biodiverse regions in the world – the Atlantic forest of eastern Bahia, Brazil – can identify the drivers of diversity in tropical forests and provide useful information for biological conservation.Aims: To understand the role of both climate and geographical location on variation in tree species composition in a region characterised by an abrupt transition from wet forests to semi-arid thorn-woodlands. To test whether a regional classification of forests according to elevation belts and leaf flush pattern is consistent with floristic composition.Methods: We submitted 14,094 tree species occurrence records and 31 geo-climatic variables prepared for 57 sites in eastern Bahia, Brazil, to multivariate and regression analyses and variance partitioning.Results: Climate and space were both significantly (P ≤ 0.05) contributing to explaining floristic variations. Actual evapotranspiration, duration of water deficit, and minimum temperature of coldest month were the main predictors. Floristic differences were significant except when comparing evergreen lower plains and upper plains forests.Conclusions: Although distance among sites may play an important role, species composition is chiefly influenced by environmental gradients. This highlights environmental heterogeneity as a key factor in the planning of biodiversity conservation in tropical forests.

­­­Rudgea agresteophila and R. hileiabaiana (Palicoureeae, Rubiaceae): two new species from eastern Bahia, Brazil

This work is part of a larger ongoing study of taxonomy and systematics of Rudgea (Rubiaceae), with the recognition of two new Brazilian species, R. agresteophila and R. hileiabaiana, described and illustrated here. The new species occur in the eastern Bahia State, Brazil, which is a place of high diversity for Rudgea. Rudgea agresteophila is morphologically distinct within the genus, by the combination of thickly coriaceous leaves, flowers with long calyx-tube and fruits crowned by a persistent calyx up to 6 mm long; and is known only from the type locality, in the municipality of Jequié. Rudgea hileiabaiana is distinguished by its coriaceous leaves, up to 30 cm long and round to cordate base, broadly infundibular corolla and unexpanded calyx; and it is restricted to southern Bahia. Detailed data on distribution and habitat, phenology and conservation status of both species are presented.

Mezilaurus revolutifolia (Lauraceae), a new species from Brazilian Atlantic Forest

A new species of Lauraceae, Mezilaurus revolutifolia F. M. Alves & P. L. R. Moraes from eastern Bahia, Brazil, is described and illustrated. This is the second species of the genus known to be endemic to the Brazilian Atlantic forest as previously only M. navalium (Allemao) Taub. ex Mez was known from this region. M. revolutifolia is distinguished from all other species of the genus by its revolute and glabrous leaves and glabrous racemose inflorescences with glabrous flowers clustered at the tips of the lateral branches.

A new species of smooth horned frog, genus Proceratophrys Miranda-Ribeiro (Amphibia: Anura: Cycloramphidae), from the Atlantic Rainforest of eastern Bahia, Brazil

A new species of smooth horned frog, genus Proceratophrys Miranda-Ribeiro (Amphibia: Anura: Cycloramphidae), from the Atlantic Rainforest of eastern Bahia, Brazil

A new species of smooth horned frog, genus Proceratophrys Miranda-Ribeiro (Amphibia: Anura: Cycloramphidae), from the Atlantic Rainforest of eastern Bahia, Brazil

We describe a new species of smooth horned frog related to the Proceratophrys appendiculata complex, constituting the northernmost record of that complex for the Atlantic Forest remnants in eastern Bahia, northeastern Brazil, within a region known as Vale do Jiquiriçá. Proceratophrys sanctaritae sp. nov. is diagnosed from all congeners by the combination of medium size (snout–vent length 38.4–45.5 mm), single and long uni-cuspidate palpebral appendage, rostral appendage longer than upper lip width, presence of preocular crest, frontoparietal crest poorly developed, color of ventral surfaces, and acoustic parameters of the advertisement call.

A New Species of the Bokermannohyla circumdata Group (Anura: Hylidae) from the Coastal Forests of Bahia, Northeastern Brazil

We describe a new species of tree frog related to the Bokermannohyla circumdata group, the northernmost record from Atlantic Forest remnants in eastern Bahia, northeastern Brazil, within regions known as Vale do Jiquiriçá, Baixo Sul, and Litoral Sul. The new species is diagnosed by medium size (snout–vent length 46.8–64.1 mm), head longer than wide, small tympanum, posterior surfaces of thighs with dark brown transverse stripes without additional thin stripes between them, vocal slits in adult males, and distinct advertisement call with a single note composed of 30–110 pulses distributed within 2–9 pulse groups, similar to the bleating of a goat. The new species is morphologically similar to B. hylax and B. lucianae, but is readily distinguished by the presence of barred posterior surfaces on the thighs without thin stripes between them (immaculate in B. lucianae; thin stripes intercalated with wider stripes in B. hylax) and by its distinct vocalization.

Validation of Neoraputia (Galipeae, Rutaceae) and description of two new species from Eastern Brazil

The name Neoraputia was published without citation of the type, making it and the names of the four species transferred to it invalid. The genus name and combinations are validated here. Lectotypes are chosen for the basionyms, Aruba alba, Raputia magnifica, R. paraensis, and Raputia trifoliata. Two new species, Neoraputia micrantha and N. calliantha, from forests of eastern Bahia, Brazil, are described.

Are women reservoirs of traditional plant knowledge? Gender, ethnobotany and globalization in northeast Brazil

This study examines the degree to which knowledge of traditional plant medicine is gendered among communities settled near Chapada Diamantina National Park in eastern Bahia state, northeast Brazil. Employing a quantitative analysis of a sample plant pharmacopoeia, I focus on the relationship between gender, age and the socioeconomic impacts of globalization in this tropical region. Results indicate that women are more familiar with both the field identities and the medicinal values of the local flora than are men. This division is pronounced among older participants (30–80 years) who represent a reservoir of medicinal plant knowledge that is in danger of disappearing. I suggest that this heightened understanding among women is due to historical gender divisions of space and labour; the inherently high potential for medicinal plant identification and collection in anthropogenic habitats; and the role of women as primary healthcare givers for the family.

REAVALIAÇÃO DA EVOLUÇÃO GEOLÓGICA EM TERRENOS PRÉ-CAMBRIANOS BRASILEIROS COM BASE EM NOVOS DADOS U-PB SHRIMP, PARTE I: LIMITE CENTRO-ORIENTAL DO CRÁTON SÃO FRANCISCO NA BAHIA

This paper discusses new U-Pb SHRIMP zircon data for 12 key-exposures of several geological units exposed at the eastern border of the Sao Francisco Craton. The samples represent mostly Archean basement units within the Paleoproterozoic Eastern Bahia Belt (Orogen). Samples were collected along several E-W transects trying to more accurately assess the areal distribution of the Archean policyclic basement of the Sao Francisco Craton and to identify the limits of Paleoproterozoic metamorphic overprint resulting from the development of the Eastern Bahia Orogen. Owing to the policyclic evolution and/or high grade metamorphic conditions which most of the rock units investigated have undergone, zircon morphology and the U-Pb analytical data exhibit very complex patterns. These are characterized by a combination of inheritance, partial resetting and new zircon growth during high grade metamorphism. As a consequence, very careful and detailed analyses of cathodoluminescence imagery were required to allow distinction between inheritance, newly melt-precipitated zircon and partially reset zircons, as well as between the ages of magmatic and metamorphic events. Except for one unit (sample LH 44), which present crystallization age of ca 3000 Ma - interpreted, therefore, as the eastern extension of the Serrinha Craton – the others are ascribed to two major age groups at ca. 2870-2500 Ma and ca . 2200?-2030 Ma. The former group includes orthogneisses with crystallization ages between ca. 2870-2500 Ma, which have been mapped and interpreted, in its major extension, as juvenile Paleoproterozoic arc (Itabuna and Salvador-Curaca belts/domains). The new data presented in this study, however, indicate that these orthogneisses represent a multi-episodic collage of primitive Archean orogenic arcs, which gave rise to the Archean basement of that part of the Sao Francisco Craton. All the investigated zircon populations were extensively recrystallized at ca. 2080-2050 Ma as a result of the Eastern Bahia Belt collision. The isotopic signature and the metamorphic assemblage are suggestive of recrystallization in very deep crustal levels, under high P and T conditions. A similar metamorphic regime is recorded in the western Jequie Block (sample LC 61), so far interpreted as a cratonic area which has been stable since the Archean. Accordingly, the Eastern Bahia Belt was characterized as the deep roots of a collisional orogen, with discrete newly accreted magmas between ca . 2200? and ca. 2090 Ma - herein ascribed to the Western Bahia Orogen which was formerly referred to as the Itabuna, Salvador-Curaca and Salvador-Esplanada belts.

Resultados paleomagnéticos de los depósitos pliopleistocenos de la cuenca de Palma (Mallorca, España)

The results from the paleomagnetic analysis of the plio-pleistocene deposits located in the eastern (Bahia Azul Section) and western (Banc d'Eivissa) borders of the Palma Basin are presented in this paper. The Bahia Azul section is composite by a marine terrace at +70-74 m a.s.1., overlapped by nine littoral dune systems separated by erosional surfaces. The Banc d'Eivissa section is constituted of a lower marine terrace at +24-25 m a.s.l., buried by two dune systems, although there are more numerous in the vicinity. The lithological spectrum at both sections holds a main calcarenitic nature, but the available outcrops display a different degree of weathering making difficult the establishment of a continuous magnetoestratigraphic sequence. The paleontological content (Rosello y Cuerda, 1973) and paleomagnetic results of the Banc d'Eivissa deposits are no sufficient to establish a precise chronological sequence, and only is possible to locate them within the reverse polarity Matuyama epoch. On the contrary, the lower half of the Bahia Azul sequence (marine terrace plus the 3 first dune systems) presents a consistent reverse polarity. The paleontological content of these materials indicates an early Pleistocene age (Emilian cycle: Cuerda y Sacares, 1992) which agree with the obtained paleomagnetic results. Therefore, the whole sequence is interpreted to be located between the normal polarity chrons of Jaramillo and Olduvay (Clr. 1n and C2n of Cande and Kent, 1995) within the Matuyama epoch, but can not be totally rejected the possibility that them could be placed after the Olduvai Chron.

Chromosome Variation in Oryzomys subflavus Species Group (Sigmodontinae, Rodentia) and Its Taxonomic Implication.

A close morphological similarity among species within the Oryzomys subflavus group makes their systematic extremely difficult. Three different karyotypes have been previously detected within the O. subflavus species group in Brazil : 2n=48-50, FN=56 (Paraiba and Pernambuco); 2n=54-56, FN=62-63 (São Paulo and Minas Gerais); and 2n=50, FN=64 (Eastern Bahia). These three variants 1, 2 and 3 were morphologically very similar to each other. In Central Brazil (Goiás and Western Bahia) we found a new O. subflavus karyotype (variant 4, 2n=58, FN=72) which was clearly different from the other variants. The X chromosome was a large submetacentric unlike the acrocentric X chromosome in the three other karyotypes. All previously described variants contained two large biarmed chromosome pairs (the largest of their autosomal complement) which did not show counterparts in this new variant. Variant 4 was easily distinguishable by its morphological characters from any other variant. Thus, distinctive karyotypic and morphological characteristics and allopatric distribution of O. subflavus variant 4 suggest that it deserves a species status.

Biodemes and zymodemes of Trypanosoma cruzi strains: correlations with clinical data and experimental pathology.

With the objective of establishing biological and biochemical characteristics of a significant number of Trypanosoma cruzi strains from different geographical areas, 138 strains isolated from naturally infected humans, triatomine or vertebrate hosts were studied; 120 were isolated from different areas of Brazil and 18 from other South and Central American countries. Inocula from triatomine or culture forms were injected into suckling Swiss mice, followed by passages into mice 10 to 12 g. Biological characters and histopathological study permitted the inclusion of the strains into three Types or biodemes: I, II, III. Isoenzymic analysis confirmed a correspondence between the biodemes and zymodemes: Type I and Z2b, Type II and Z2, Type III and Z1. Results showed the ubiquitary distribution of the several types of strains. The predominance of the same Type and zymodeme in one geographical area was confirmed: Type II strains among the human cases from eastern Bahia and east of Goiás; Type III strains from humans of north Brazil and Central America and from silvatic vectors or vertebrates from other geographical areas. The biological types of strains correlate with different histopathological lesions considering cardiac involvement and neuronal lesions. These findings suggest that the biological behavior together with isoenzymes patterns and pathological pictures in the vertebrate host can be an important tool for establishing correlations between strains behavior and clinico-pathological manifestations of Chagas' disease in different geographical areas.

EDAPHIC LIMITATION OF A BRAZILIAN RAINFOREST PALM: THE ROLE OF ENERGY ALLOCATION AND COMPETITION FOR SUNLIGHT

Tropical forest palms are often associated with specific soil conditions, yet the ecological role of edaphic limitation in Palmae has seldom been considered. In the Atlantic Coastal Forest Biome of eastern Bahia, Brazil, the piassava palm (Attalea funifera) inhabits coastal podzolic soils but not nearby latosols. This paper examines the role of changing edaphic conditions and access to sunlight in the restriction of this species to tropical podzols.

Geochemical evolution of eastern Bahia, Brazil: A probable Early Proterozoic subduction-related magmatic arc

The granulitic Jequié Complex is composed of supracrustal rocks intruded during Late Archean times by batholithic high-K granites and less abundant intermediate rocks. The Caraíba Complex consists of supracrustal rocks intruded by tonalitic-granodioritic rocks and granites during Archean and Early Proterozoic times, with subordinated basic rocks. The Jacobina sedimentary sequence, the tholeiitic and calc-alkaline volcano-sedimentary Contendas-Mirante and Rio Itapicura sequences, and the granulitic Itabuna Belt — which is subdivided into mainly plutonic, tholeiitic, calc-alkaline, and shoshonitic sequences — were formed during the Early Proterozoic. In the proposed model of geotectonic evolution, the Itabuna Belt corresponds to a subduction-related continental margin magmatic arc and the Rio Itapicuru greenstone to a back-arc basin. The Jacobina sequence, composed mostly of coarse-grained clastic and metapelitic sediments, could have been formed in an aborted rift, while the tholeiitic and calc-alkaline sequences of Contendas-Mirante could represent the opening and closing stages, respectively, of a larger basin.