Diamantina Region Research Articles

How do fire and harvesting affect the population dynamics of a dominant endemic Velloziaceae species in campo rupestre?

Understanding the role of the environmental drivers that determine plant population dynamics is essential to promote the conservation of target species and their habitats. Vellozia aff. sincorana is an endemic key species from the rupestrian grasslands (campos rupestres) of the Chapada Diamantina region in the Brazilian savanna (Cerrado). The branches are important in the local culture and are harvested to light wood stoves. Synchronized flowering is triggered by fire, and no flowers have been recorded in the absence of a recent fire. We built matrix population models to project the demography of six V. aff. sincorana populations, three that had recently burned and three that had not burned for four years. Based on local harvesting practices and our population models, we assessed the long-term effects of two common harvesting techniques and different fire intervals on this species’ demography. Fire is necessary for the long-term persistence of V. aff. sincorana populations; adult survival is the most important vital rate for population persistence and it is mostly unaffected by fire. Recent fires primarily caused increases in reproductive rates, and populations are projected to decrease in size (λ<1) under fire intervals longer than 25 years. Harvest effects depend on its frequency and intensity; our models indicated that harvesting may be sustainable as long as it is low-intensity and fire also occurs periodically. As in many other fire-prone ecosystems, this species benefits from fire occurrence. These results indicate that the ‘zero-fire’ policy currently in place in the Brazilian savanna is inadequate for the conservation of this, and probably many other, Cerrado species.

Contributions to the floristic and vegetation knowledge of Espinhaço Septentrional, Bahia, Brazil

The Espinhaco range is a mountain chain that extends from the municipality of Ouro Preto in Minas Gerais to the Chapada Diamantina region in Bahia, eastern Brazil. The Serra Geral of Licinio de Almeida (SGLA) is located in the Espinhaco Septentrional in southwestern Bahia, and its biodiversity is still poorly known. In order to contribute to a better understanding of floristic diversity and the vegetation of SGLA, we have compiled a checklist of its flowering plants and characterized the phyto-physiognomy of the different plant formations. A total of 811 species in 410 genera and 97 families are recorded in our study. Based on floristic composition and ecological parameters, we recognize five plant formations as follows: (1) deciduous forest, (2) semi-deciduous forest, (3) “Cerrado” s.str., (4) rocky fields (“Campos Rupestres”), and (5) rocky Caatinga (“Caatinga Rupestre”). Our results indicate that the SGLA is a transitional area between the “Cerrado” and “Caatinga” domains and constitutes an ecological corridor that links the northern and southern portions of the Espinhaco Range supported by 24 new occurrences recorded for the state of Bahia.

Paleogeography of the Congo/São Francisco craton at 1.5 Ga: Expanding the core of Nuna supercontinent

The Congo/São Francisco (C/SF) craton, one of the largest cratons in Proterozoic paleogeography, has been lacking reliable paleomagnetic data for the supercontinent Nuna interval (ca. 1600–1300Ma). Here we provide a new paleomagnetic key pole for this craton from recently dated mafic dykes in the Curaçá (1506.7±6.9Ma) region of Brazil. The characteristic remanent magnetization (ChRM) direction D=070.6°, I=54.0° (k=22.1 and a95=13.1°) corresponds with a paleomagnetic pole at 10.1°N, 009.6°E (K=15.6, A95=15.8°), which places C/SF craton in moderate paleolatitudes at the time of remanence acquisition. Primary nature of the paleomagnetic remanence is supported by a baked-contact test. A similar ChRM direction was obtained for four Mesoproterozoic mafic intrusions in Chapada Diamantina region. The new pole, only from Curaçá, for C/SF allows us to reconstruct the extended core of the supercontinent Nuna at 1.5Ga. Based on coeval 1.5Ga and 1.38Ga magmatism in Baltica, Siberia and C/SF, we favor the position where Southwest Congo is reconstructed against present South-Southeast (S-SE) Baltica. We explore two alternative 1.5Ga reconstructions of Nuna’s core. In both of them Baltica and Laurentia are shown in the well-defined NENA (Northern Europe North America) fit, together with Siberia in a tight fit to northern Laurentia. In reconstruction option A, more traditional fit of Amazonia with Baltica is shown, modified from the geologically based SAMBA (South AMerica BAltica) model to accommodate paleomagnetic data. In this option, however, West Africa must be extricated from SAMBA because C/SF has taken its place. For reconstruction option B, Amazonia is shifted to lie adjacent to NE Laurentia and West Baltica. In both options SW Congo is reconstructed against S-SE Baltica, but in option B there is a tighter fit between them, and there is a better match with our new paleomagnetic data for C/SF. In either option, separation of C/SF from Baltica and Siberia probably occurred at 1.38Ga, the age of pronounced mafic magmatism throughout this sector of Nuna.

Flora da Bahia: Podocarpaceae

The flora of Podocarpaceae, the only family of gymnosperms native to Bahia, Brazil, is presented here. Two species of Podocarpus are recognized: P. lambertii, occurring in the Chapada Diamantina region, and P. sellowii, occurring in the Chapada Diamantina and also in the montane and submontane forests in southern Bahia. Descriptions, identification key, illustrations and general comments on the taxa are presented.

On the enigmatic troglobitic scorpion Troglorhopalurus translucidus: distribution, description of adult females, life history and comments on Rhopalurus lacrau (Scorpiones: Buthidae)

ABSTRACT We describe for the first time the adult female of the troglobitic scorpion Troglorhopalurus translucidus Lourenco Baptista & Giupponi, 2004, and broaden its known distribution to other sandstone caves at Chapada Diamantina's region. The life history of T. translucidus is reconstructed through morphometric measurements, with a multivariate analysis applied on a set of 16 specimens in all stages (including the holotype) and biological notes. The ontogeny of T. translucidus has seven stages and the litter size is 43 (n = 1). We discuss the isolation of T. translucidus and Rhopalurus lacrau Lourenco & Pinto-da-Rocha, 1997 in caves of Chapada Diamantina, and discuss their troglomorphisms (autapomorphies) among other species related with Rhopalurus . Both species must be considered fragile due their restricted endemism at Chapada Diamantina.

New record and cytogenetic analysis of Psammolestes tertius Lent & Jurberg, 1965 (Hemiptera, Reduviidae, Triatominae) from Bahia State, Brazil.

This paper reports on the first occurrence of Psammolestes tertius in the Chapada Diamantina region, located in the city of Seabra, Bahia State, in northeastern Brazil. Following an active search, 24 P. tertius specimens were collected from Phacellodomus rufifrons (rufous-fronted thornbird) nests. The insects did not present any symptoms of infection by Trypanosoma cruzi. P. tertius males were cytogenetically analyzed, and the results were compared with those of other specimens from the Brazilian State of Ceará. Triatomines from both locations presented the same cytogenetic characteristics: 22 chromosomes, little variation in the size of the autosomes, Y chromosomes that were larger than the X chromosomes, a chromocenter formed only by the sex chromosomes during prophase, and autosomes lacking constitutive heterochromatin. However, it is important to note that this species shows intraspecific chromosomal variation. In light of the results obtained, it is recommended that more studies be performed to characterize P. tertius. These studies will be particularly helpful in understanding this species in ecological, biological, biogeographical, and phylogenetic terms.

First pollen survey of murundus in the Chapada Diamantina region of the state of Bahia, Brazil

This was a pollen survey, in which we analyzed the sediments and moss polsters of murundus (termite mounds) in the Chapada Diamantina region of the state of Bahia, Brazil. Palynological treatment revealed the presence of 53 pollen types in murundus sediments, of which 23 were related to plants in the semi-arid zone and 30 remained unidentified. In moss polster samples, the pollen assemblage comprised 42 pollen types for which taxonomic affinities were identified and 54 for which they were not. In our comparison of the two pollen assemblages, we found that moss polsters and murundu sediments shared 15 pollen types. For some of the pollen grains in the murundus sediments, it was not possible to make reliable interpretations because of small number of grains and the poor state of conservation. In contrast, the pollen analyses of the moss polster samples showed that they could represent a useful tool for studies of pollen rain. To our knowledge, this is the first study of murundus as natural pollen collectors. Our findings suggest new possibilities for the use of the pollen records preserved in termite mounds.

A new uncommon epilithic Eunotia (Bacillariophyceae, Eunotiaceae) from the Chapada Diamantina region, Northeast Brazil

A new uncommon epilithic diatom, Eunotia relicta sp. nov., is described from a small oligotrophic, acidic stream in the Chapada Diamantina region, northeast Brazil. Eunotia relicta is a typical eunotioid form with a pronounced arch on the dorsal side of the valve mainly in smaller valves. Contrary to most Eunotia species, Eunotia relicta does not possess rectangular frustules in girdle view. Until now, this characteristic was only observed in a few species such as E. charliereimeri Edlund &amp; Brant, E. sarraceniae E.E. Gaiser &amp; J.R. Johansen and E. arcuoides Foged, all of them considered asymmetric along the valve plane. Some interesting morphological features of the new species are broad copulae on the dorsal side, an inconspicuous single conical spine on the valve face near the margin at both poles, and the irregularly thickened interstriae. Moreover, each valve has irregular projections at the dorsal valve face margin/mantle juncture and up to three rimoportulae per valve located on the mantle. These features associated with the distinct valve outline set it apart from E. charliereimeri, E. sarraceniae and E. arcuoides, which have no spines, smooth valve faces and 1–2 rimoportulae per valve.

New additions of coccoid green algae to the phycoflora of Brazil and the Neotropics

The present study presents 11 new additions of coccoid green algae to the phycoflora of Brazil, including the first record of the genus Westellopsis for the neotropical region. Samples of periphyton and plankton were collected in two areas of the Marimbus Wetlands (the Marimbus do Baiano and Marimbus do Remanso, within the Marimbus-Iraquara Environmentally Protected Area), in the Chapada Diamantina Region of the state of Bahia, Brazil. Sample collection occurred during dry periods (April-June and August 2011) and rainy periods (October-December 2011 and February 2012). Here, we describe the taxa identified from the 56 samples collected.

Piriqueta crenata, a new species of Turneraceae (Passifloraceae s.l.) from the Chapada Diamantina, Bahia, Brazil

In this study, we describe and illustrate Piriqueta crenata, a new species from the Chapada Diamantina region, Bahia, Brazil. It is similar to and was initially identified as P. flammea from which it can be distinguished by the cuneate leaf blade bases (vs. rounded), slightly discoloured leaves (vs. strongly discoloured), inflorescences of fewer flowers (1–3 vs. 3–6), olive-green calyx when dry (vs. blackened), and yellow corolla (vs. orange red). Piriqueta crenata is only known from a single small savanna nested in the semiarid Chapada Diamantina region, close to areas under anthropogenic influence. Therefore, we evaluate the species as Critically Endangered.

Pedras na areia. As indústrias líticas e o contexto horticultor do Holoceno Superior na região de Diamantina, Minas Gerais

This paper presents the later pre-colonial occupations in the Diamantina region (North-Center of Minas Gerais state, central Brazil), based on UFMG researches. The focus here is on interpretative proposal for roles played by rockshelter sites in the regional occupation system in the Upper Holocene, when there are clear remains of domesticated plants use, but few ceramic remains and no habitation sites. Then, I make some considerations about how the Brazilian Archaeology usually think about horticulturalists archaeological sites in central Brazil.

Caracterização morfológica e molecular de genótipos de mangaba

O objetivo do trabalho foi verificar a divergência genética entre 25 genótipos de mangaba da região de Iramaia-Chapada Diamantina-Bahia, utilizando os marcadores morfológicos e os marcadores RAPD. As seguintes aferições foram realizadas nos frutos maduros: diâmetro longitudinal (DL) e transversal (DT), massas do fruto (MF), da semente (MS) e da polpa (MP), rendimento de polpa (%P) e a contagem do número de sementes (NS). Os caracteres químicos avaliados no fruto maduro foram: pH, acidez (Ac), sólidos solúveis totais (SST), ácido ascórbico (AA), açúcar total (ACT) açúcar redutor (ACR), açúcar não redutor (ACNR) e relação sólidos solúveis totais: acidez (SST/Ac). Para a amplificação, foram testados 51 random primers. Os resultados médios das aferições foram: DL (37,03 mm), DT (34,34 mm), MF (24,45 g), MS (2,42 g), MP (22,03 g), e NS (11,14). Para as avaliações químicas, foram verificados os resultados médios: %P (88,44%), AA (80,23 mg 100 g-1), Ac (0,96%), pH (3,67), SST (14,15 ºBrix), ACT (9,26 mg 100 g-1), ACR (5,13 mg 100 g-1), ACNR (4,13 mg 100g-1) e SST/Ac (14,56 mg 100g-1). Oito random primers foram selecionados por apresentarem bandas mais intensas, e seis (OPA 08, OPB 12, OPB 19, OPH 15, OPH 18 e OPH 19) geraram 28 regiões de bandas polimórficas. Dentre os marcadores morfológicos, MF e MP foram os que mais efetivamente contribuíram para a divergência genética. A formação de seis e sete grupos para os marcadores moleculares e morfológicos, respectivamente, indicou a presença de variabilidade genética na população avaliada.

Age constraints on crystal-tuff from the Espinhaço Supergroup — Insight into the Paleoproterozoic to Mesoproterozoic intracratonic basin cycles of the Congo–São Francisco Craton

The U–Pb data from the volcanic and detrital zircon grains of the Tombador Formation in Chapada Diamantina, Bahia, provide the depositional age of the top of this unit and define the main sedimentary sources of the Archean, Paleoproterozoic and Mesoproterozoic Eras. The lithofacies, petrographic and geochemical data from crystal-tuff samples indicated that a volcanic source was located to the east of the Chapada Diamantina region. The available zircon data defined three first-order intracratonic basinal cycles, including the Lower (Statherian), Middle (Calymmian) and Upper (Stenian–early Tonian) Espinhaço basins. These sequences are well exposed at the Espinhaço Supergroup type-section in the Chapada Diamantina region. The zircon Hf isotope data from the 1.4Ga crystal-tuff in the Middle Espinhaço and the 1.2Ga tuffaceous rock in the Upper Espinhaço suggested different sources, with model ages of 2.1 to 1.9Ga and <1.9Ga, respectively. The tectonic development of these Paleoproterozoic to Mesoproterozoic intracratonic basins can be explained by the far-field stress at the paleoplate margins, which has been shown in other Phanerozoic intracratonic basins. The data presented here support a tectonic scenario in which the Congo–São Francisco paleoplate interior recorded the main global events related to the geodynamic processes after the Columbia supercontinent collage and the formation and fragmentation of the Rodinia supercontinent.

Diversity and distribution of the bryophyte flora in montane forests in the Chapada Diamantina region of Brazil

Bryophytes constitute an important component of tropical rain forests, which provide microhabitats favorable for their establishment. Bryophytes are also quite responsive to changes in microclimate, which makes them good bioindicators. This study aimed to determine the diversity and distribution of bryophytes in upper and lower montane forests of the Chapada Diamantina region of the state of Bahia, Brazil. To that end, we studied community aspects such as richness, diversity, substrates colonized, life forms and floristic similarity between areas and regions. In 2007 and 2008, we collected specimens from six forest sites, located from the north to the south of the Chapada Diamantina region. We identified a total of 205 infrageneric taxa. In comparison with the lower montane forests, the upper montane forests presented higher diversity and species richness, as well as greater numbers of substrates colonized, life form types, species of restricted geographic distribution and species typical of shaded areas. We also found low similarity in the species composition, the populations of the upper and lower montane forests forming two large and distinct groups. Although presenting relatively high floristic homogeneity among themselves, the Chapada Diamantina areas presented little similarity with those of the Atlantic Forest. This can be explained by the differences between the two regions in terms of environmental conditions, precipitation, seasonality, elevation and continentality.

DOCUMENTING ARCHITECTURAL HERITAGE IN BAHIA, BRAZIL, USING SPHERICAL PHOTOGRAMMETRY

Abstract. The Cultural Heritage disappears at a rate higher than we are able, not only, to restore but also to document: human and natural factors, negligence or worst, deliberate demolitions put in danger the collective Architectural Heritage (AH). According to CIPA statements, the recording is important and has to follow some guidelines. The Architectural and Urban Heritage data have to be historically related, critically assessed and analyzed, before to be organized according to a thematic structure and become available for further uses. This paper shows the experiences developed by the Laboratory of Computer Graphics applied to Architecture and Design (LCAD), at the Architecture School of the Federal University of Bahia (FAUFBA), Brazil, in cooperation with the Università Politecnica delle Marche (UNIVPM, DICEA Department), Italy, in documenting architectural heritage. The research set up now has been carried out in the historical sites of Bahia, as Pelourinho neighborhood, a World Heritage by UNESCO. Other historical sites are in the plan of this survey, like the cities of Lençóis and Mucugê in Chapada Diamantina region. The aim is to build a technological platform based on low cost digital technologies and open source tools, such as Panoramic Spherical Photogrammetry, Spatial Database, Geographic Information Systems, Three-dimensional Geometric Modeling, CAD technology, for the collection, validation and dissemination of AH.

Species richness and distribution of bryophytes within different phytophysiognomies in the Chapada Diamantina region of Brazil

The Chapada Diamantina ecoregion is within the caatinga (shrublands) biome of Brazil. Environmental factors determine the phytophysiognomies that distinguish the ecoregion from the surrounding areas. This study aimed to investigate the distribution of bryophyte flora in this ecoregion, by phytophysiognomy and elevational zone. Analyzing specimens we collected from five municipalities in the region, together with specimens (previously collected from the region) in herbaria, we identified 400 taxa. The phytophysiognomies that presented the highest species richness and the greatest numbers of exclusive taxa were forests and campos rupestres (dry, rocky grasslands), which respectively accounted for 51% and 40% of the taxa, compared with only 5% and 4%, respectively, for the caatinga and cerrado (savanna). Species richness and the numbers of exclusive taxa were highest in the lower and upper montane zones. There was a predominance of neotropical taxa and a significant number of disjunct species found in Brazil and in the Andes region. We conclude that the Chapada Diamantina region is an important center of bryophyte diversity, harboring not only a great number of species overall but also a considerable number of species exclusive to the region, primarily in forests and campos rupestres at elevations above 800 m.

Idades U-Pb em zircão do conglomerado diamantífero de Grão Mogol (Supergrupo Espinhaço): implicações para a origem dos diamantes da Serra do Espinhaço em Minas Gerais

The Espinhaco Range in the Grao Mogol region, center-north of Minas Gerais state, is composed by fine grained quartzites with large cross stratifications (Resplandecente Formation), which are covered with erosional unconformity by monomictic conglomerates, and medium to coarse grained quartzites (Grao Mogol Formation), both units belonging to the Espinhaco Supergroup, of Proterozoic age. At the locality known as Pedra Rica (signify Rich Rock, an old diamond digging), rocks of these formations were sampled and separated detrital zircons to acquire U-Pb by Laser Ablation Inductively LA-ICPMS) ages. The analyzed grains are rounded to slightly rounded and show oscillatory zoning. The obtained results indicate a maximum depositional age of 1,595 ± 20 Ma for the Resplandecente Formation, and 1,052 ± 50 Ma for the Grao Mogol Formation. The comparison between the obtained data and the available ages for the Diamantina region and proximities, in the same diamond province, indicates a strong evidence for the existence of at least two primary mineralizing events in the basin, in the age range of 1.35 to 1.05 Ga.

A new dwarf species of Proceratophrys Miranda-Ribeiro, 1920 (Anura, Cycloramphidae) from the highlands of Chapada Diamantina, Bahia, Brazil

A new species of Proceratophrys is described from the highlands of northeastern Brazil. Molecular and morphologicaldata suggests that Proceratophrys redacta sp. nov. is sister to P. minuta, and related to P. schirchi and P. cristiceps. Thenew species is diagnosed by its small size, absence of rostral and palpebral appendages, sagittal ridges interrupted, absenceof postocular swellings, snout vertical in profile and dorsal coloration lacking distinct ocelli. The new species representsanother example of endemism for the genus Proceratophrys in Chapada Diamantina region, and of another appendagelesssmall-sized species associated with highlands. The phylogenetic results indicate that current morphological groupings in Proceratophrys may not represent natural groups.

First precise U–Pb baddeleyite ages of 1500 Ma mafic dykes from the São Francisco Craton, Brazil, and tectonic implications

The São Francisco Craton (SFC) is an Archaean–Proterozoic craton that hosts a significant number of mafic intrusions. Previous attempts to date the igneous emplacement of these rocks are limited to a few poor precision Rb–Sr and Sm–Nd isochrons. Here, dykes from the Curaçá belt, in the northeastern portion of the craton, as well as from the Chapada Diamantina region in the central part, were dated using U–Pb on baddeleyite (ID-TIMS). These dykes yielded similar baddeleyite U–Pb ages of 1506.7±6.9Ma (Curaçá) and 1501.0±9.1Ma (Chapada), with converging trends indicating a possible magmatic centre located near the western margin of the São Francisco Craton. The two dyke swarms are subalkaline, and have light rare earth enriched chondrite-normalized patterns but the Curaçá dykes have lower Mg-number and higher abundances of most incompatible trace elements than the Chapada dykes. Geochemical modelling and trace element ratios suggest that the two dyke swarms had different petrogenesis, with the Chapada dykes being derived from more depleted mantle sources and the Curaçá dykes from enriched sources, however the mantle sources of both dyke swarms appear to have had contributions from an enriched plume. Current geochronological and palaeomagnetic data suggest a coherent São Francisco–Congo block from at least the late Mesoproterozoic until the opening of the South Atlantic (ca. 130Ma ago). The discovery of ca. 1500Ma intrusions in the São Francisco Craton is a major step forward to a more complete barcode record for the SFC–Congo Craton, which can be used in future palaeo-continental reconstructions.

Contribuição de variáveis ambientais à estrutura de comunidade de anuros no Domínio da Caatinga of Brazil

To ascertain the influence of environmental variables on the structure of anuran communities, we conducted tests to determine which variables best explain the spatial distribution patterns of different communities of anurans in a rocky, montane environment characterized mainly by open habitats and gallery forests. The study area is the Sete Passagens State Park in the State of Bahia, Brazil, an area included in the Chapada Diamantina Region and in the Caatinga Morphoclimatic Domain. We sampled 20 plots (60 × 25 m) during two rainy seasons, and measured 13 environmental variables. The environmental matrix was reduced to four synthetic axes through the principal component analysi, and the anuran community matrix was reduced to a synthetic axis through the non-metric multidimensional scaling method. We tested the association between environmental axes (independent variables) and community composition (dependent variable) using a multiple regression analysis. The single axis significantly associated with the species of anurans found in any given plot is Principal Component 1, in which the major contributors to variation are factors involving vegetation structure, listed in descending order, as follow: percentage of leaf litter, density of trees, canopy height, soil moisture, and percentage of understory, shrub, and herb layers. The ordination of the anuran community showed an environmental gradient from the Campo Rupestre to Semideciduous Forest patches, characterized mainly by the gradual increase of layering in the vegetation.