Guiana Shield Region Research Articles

Cyperus verloovei Sect. Incurvi, a New Species from the Guiana Shield Region of South America

Cyperus verloovei Sect. Incurvi, a New Species from the Guiana Shield Region of South America

Predicting the loss of forests, carbon stocks and biodiversity driven by a neotropical ‘gold rush’

The loss of tropical forests represents a major threat to biodiversity. With accelerating deforestation in large parts of the Amazon, the Guiana Shield region, with its large expanse of closed forest cover, has the potential to play a crucial role in both climate change mitigation and biodiversity conservation. However, the region is now facing increasing deforestation pressures, primarily from artisanal gold mining activities concentrated in the nation of Guyana. To identify areas of Guyana at the highest risk of deforestation over the next 25 years, we employed a spatio-temporal modelling approach that accounted for the stochastic and contagious nature of deforestation. Our model predicted a 9 % net decrease in total forest cover by 2043. While the primary drivers of deforestation were mining and human settlements, protected areas were shown to reduce the probability of deforestation. Therefore, we assessed the potential impact of a proposed expansion of the protected area network in Guyana, on forest loss, carbon stocks and habitat loss for the country's most threatened forest vertebrates. Establishing the proposed protected areas would reduce forest loss by 17 %, predicted habitat losses by an average of 1.9 % per vertebrate group, and aboveground carbon emissions by 466,968 t over the next 25 years. These findings highlight the utility of using predictive models to identify areas at risk of future deforestation, which can contribute to the development of effective strategies against tropical forest loss, biodiversity loss and climate change.

Giants of the Amazon: How does environmental variation drive the diversity patterns of large trees?

For more than three decades, major efforts in sampling and analyzing tree diversity in South America have focused almost exclusively on trees with stems of at least 10 and 2.5 cm diameter, showing highest species diversity in the wetter western and northern Amazon forests. By contrast, little attention has been paid to patterns and drivers of diversity in the largest canopy and emergent trees, which is surprising given these have dominant ecological functions. Here, we use a machine learning approach to quantify the importance of environmental factors and apply it to generate spatial predictions of the species diversity of all trees (dbh ≥ 10 cm) and for very large trees (dbh ≥ 70 cm) using data from 243 forest plots (108,450 trees and 2832 species) distributed across different forest types and biogeographic regions of the Brazilian Amazon. The diversity of large trees and of all trees was significantly associated with three environmental factors, but in contrasting ways across regions and forest types. Environmental variables associated with disturbances, for example, the lightning flash rate and wind speed, as well as the fraction of photosynthetically active radiation, tend to govern the diversity of large trees. Upland rainforests in the Guiana Shield and Roraima regions had a high diversity of large trees. By contrast, variables associated with resources tend to govern tree diversity in general. Places such as the province of Imeri and the northern portion of the province of Madeira stand out for their high diversity of species in general. Climatic and topographic stability and functional adaptation mechanisms promote ideal conditions for species diversity. Finally, we mapped general patterns of tree species diversity in the Brazilian Amazon, which differ substantially depending on size class.

Revision of Limnocoris Stål (Heteroptera: Nepomorpha: Naucoridae) of the Guiana Shield and Amazon regions.

The species of Limnocoris of the Guiana Shield and Amazon regions of South America are revised, including the descriptions of five new species: L. amazonensis n. sp., L. moreirai n. sp., and L. yanomami n. sp. from Brazil, L. flavescens n. sp. from Venezuela, and L. inflatus n. sp. from Suriname. Further, supplemental descriptions are provided for four previously described species: L. burmeisteri De Carlo, L. fittkaui De Carlo, L. menkei La Rivers, and L. surinamensis Nieser n. stat.; the latter was a subspecies and is here elevated to full species status. The following synonymies are proposed, with junior synonyms in brackets: L. burmeisteri De Carlo [L. lautereri Nieser, Chen & Melo n. syn.] and L. menkei La Rivers [L. birabeni De Carlo n. syn., L. bruchi De Carlo n. syn.]. An illustrated taxonomic key and distribution maps are also presented.

New species and new distributional records of the hygropetric water scavenger beetle genus Oocyclus Sharp (Coleoptera: Hydrophilidae) from the Guiana Shield

The species of the water scavenger beetle genus Oocyclus Sharp are reviewed for the Guiana Shield region of South America. Seven species are recorded, including one here described as new: Oocyclus paraiso sp. n. from the Brazilian state of Pará. New records of previously described species are also reported for Brazil, French Guiana, Guyana, and Suriname. The aedeagus of O. coromoto Short & García is illustrated for the first time. As with all other known members of the genus, all Guiana Shield species are hygropetric habitat specialists. A key to the Oocyclus of the Guiana Shield is provided.

Venomics of the Scorpion Tityus ocelote (Scorpiones, Buthidae): Understanding Venom Evolution in the Subgenus Archaeotityus

The subgenus Tityus (Archaeotityus) includes small variegated species considered until recently, a basal group within Tityus, one of the most diverse and medically relevant genera of scorpions in the New World. Archaeotityus species are distributed in the humid forests of Lower Central America and the Choco, Guiana Shield, and Amazonian regions. Due to their size and habits, Archaeotityus species are not usually considered dangerous, however, there are some clinical reports that show otherwise. To contribute to the toxinological knowledge of these poorly explored species, we characterized the venom of Tityus ocelote from three localities in Costa Rica. In addition, we assessed the evolutionary relationships of putative sodium channel-modulating peptides found in this species with those reported for other members of the genus, through a maximum likelihood phylogenetic analysis based on their amino acid sequences. We observed the presence of homologs of previously identified NaTx from the species Tityus (Archaeotityus) clathratus and some other putative Na+ and K+ channel modulating peptides related to the T. bahiensis group. In addition, we sequenced some peptides related to toxins present in the venom of the subgenus Atreus, such as those reported for T. obscurus, T. pachyurus, and the Costa Rican endemic species T. dedoslargos. Our phylogenetic analysis suggests that the venom of this Archaeotityus species is very complex and that some of the ion channel toxins expressed in it are related to distinct lineages within the genus Tityus, which could represent a plesiomorphic condition conserved in this group of scorpions of the New World.

A New Species of Sternopygus (Gymnotiformes: Sternopygidae) from the Atlantic Coast of the Guiana Shield

Sternopygus sabaji, new species, is described from the Atlantic drainages of the Guiana Shield region of South America using traditional methods of morphometrics and meristics and microcomputed tomography (µCT) scans for osteological analysis. The new species is diagnosed from all other species of Sternopygus by the lack of dentition on the anteroventral surface of the endopterygoid and by the possession of a wider mouth. It further differs from its congeners by the following combination of characters: reduced humeral spot with low-contrast and poorly defined margins, possession of a light-colored mid-lateral stripe along posterior portion of lateral line, possession of 1–3 dark saddle-like markings along dorsum of smaller individuals, and a relatively low precaudal vertebrae count. This work provides the first description of a species of Sternopygus that is endemic to the Guiana Shield, joining S. astrabes and S. macrurus in elevating the species richness of the clade in that region to three species and the total number of valid Sternopygus to ten species.

The Rudgea hostmanniana complex (Rubiaceae) in the Guiana Shield region

A taxonomic revision of the Rudgea hostmanniana complex in the Guiana shield region is presented. This group includes species with sheathing stipules bearing dorsal appendages, thick glabrous leaves lacking domatia, inflorescences thyrsoid to glomerulate but not regularly dichotomous, a calyx tube absent or very short, a corolla tube 2–7(–13) mm long, and fruits usually brownish when immature and turning red or orange at maturity. Eight species are recognized, among which Rudgea billietiae, endemic to Kaw Mountain in French Guiana, is newly described and illustrated; it is assessed as Endangered according to IUCN criteria. The other species are R. bolivarensis, R. cornigera, R. coussareoides, R. hostmanniana, R. maypurensis, R. pungens, and R. tanaosepala. A key to the species is presented, as well as a table summarising their diagnostic characters.

First Report of Belladessus Miller and Short, 2015 from Brazil with Description of Two New Species (Coleoptera: Dytiscidae: Hydroporinae: Bidessini)

Belladessus Miller and Short, 2015 is reported from Brazil for the first time. Two new species in the genus are described: Belladessus espinhasso, new species is described from the state of Minas Gerais, while Belladessus minutopunctatus, new species is described from the Federal District. Belladessus femineus Miller and Short, 2015 is reported from the northern Brazilian state of Roraima. The new species were collected in the Brazilian Shield, expanding the geographic distribution of the genus that until now was limited to the Andean and the Guiana Shield regions of South America.

Review of the Neotropical water scavenger beetle genus Tobochares Short & García, 2007 (Coleoptera, Hydrophilidae, Acidocerinae): new lineages, new species, and new records.

The water scavenger beetle genus Tobochares Short & García, 2007 currently contains ten species, including one known but formally undescribed taxon. Although Tobochares was revised in 2017, ongoing fieldwork as well as an expanded concept of the genus has led to the recognition of numerous additional species. Here a combination of morphological and molecular data is presented to review this newly found Tobochares diversity. Fifteen new species are described from South America, bringing the total number of known species to 25: Tobochares akoeriosp. nov. (Suriname), T. arawaksp. nov. (Guyana), T. anthonyaesp. nov. (Venezuela: Bolívar), T. aturessp. nov., (Venezuela: Amazonas), T. benettiisp. nov. (Brazil: Amazonas), T. canaimasp. nov. (Venezuela: Bolívar), T. communissp. nov. (Brazil: Amapá and Roraima, Guyana, Suriname, Venezuela: Bolívar), T. fusussp. nov. (Brazil: Amapá, French Guiana), T. goiassp. nov. (Brazil: Goiás), T. kappelsp. nov. (Suriname), T. kolokoesp. nov. (Suriname), T. luteomargosp. nov. (Venezuela: Bolívar), T. micropssp. nov. (Suriname), T. pemonsp. nov. (Venezuela: Bolívar), and T. romanoaesp. nov. (Brazil: Roraima). Both morphological and molecular analyses support four clades within the genus, which are here diagnosed and described as species groups. New distributional records are provided for T. kusad Kohlenberg & Short, 2017 and T. sipaliwini Short & Kadosoe, 2011, both of which are recorded from Brazil for the first time. Previously restricted to the Guiana Shield region of South America, the distributional range of the genus is now broadly expanded to include localities as far south as the central Brazilian state of Goiás. Consistent with the biology of the previously described species, almost all the new species described here are associated with seepage and wet rock habitats. Remarkably, one species, T. fusussp. nov., was collected in both seepage habitats as well as in the rotting fruits of Clusia Linnaeus (Clusiaceae), making it one of the few known acidocerines with terrestrial habits outside of the genus Quadriops Hansen, 1999. High-resolution images of most species are included, as well as a key to species groups, species, and habitat photographs.

New records of Platynectes (s. str.) diving beetles from South America with description of two new species (Coleoptera: Dytiscidae: Agabinae)

Diving beetles in the genus Platynectes (s. str.) in South America are relatively large and charismatically colored, yet relatively rare in museum collections. Recent fieldwork in northern and central South America has resulted in the collection of hundreds of new specimens that substantially expand our distributional knowledge of the genus. Here, we provide new distributional records for Platynectes decemnotatus (Aubé, 1838), P. garciai Gustafson, Short & Miller, 2016, P. submaculatus (Laporte, 1835), and P. tafelbergensis Gustafson, Short & Miller, 2016. In addition, two new species were identified and described herein: Platynectes bicolor sp. nov. of the P. ornatifrons species group from Brazil (Goiás and Mato Grosso do Sul), and P. colombicus sp. nov. of the P. submaculatus species group from the Guiana Shield region of eastern Colombia. These new records suggest that Platynectes (s. str.) is likely widespread across the Brazilian and Guiana Shield regions of the continent, and that some individual species have substantial range sizes of nearly 2000 km. An updated key to the species groups of Neotropical Platynectes (s. str.) and to the species of P. submaculatus species group are provided.

A New Hyphessobrycon (Characiformes: Characidae) from the Guiana Shield in Northern Brazil

A new species of Hyphessobrycon from a tributary of the Rio Paru do Oeste (Rio Trombetas basin), at the lower Amazon basin draining the Guiana Shield region in Para State, Brazil, is described. The new species presents a unique combination of an irregularly-shaped humeral blotch, a broad diffuse midlateral stripe, and a roughly triangular caudal peduncle blotch. The new species is herein included in the Hyphessobrycon agulha species-group, and comparisons with species belonging to this group and to a similar-looking non-congener, Hemigrammus bellottii, are presented.

Rapid assessment of the ichthyofauna of the southern Guiana Shield tributaries of the Amazonas River in Pará, Brazil

ABSTRACT The Northern Pará Drainage System encompasses the left-bank tributaries of the Amazonas River in the southern Guiana Shield region of Pará state, Brazil. Five of the region’s state protected areas are considered strategic for the conservation of its biodiversity. In the present study, we assessed the ichthyofauna of the five state protected areas of the Northern Pará Drainage System. Seven expeditions were conducted between January 2008 and January 2009, which surveyed stretches of the Cuminá, Cuminapanema, Curuá, Jari, Mapuera, Nhamundá, and Paru rivers. These surveys yielded 286 species belonging to 38 families and eight orders, including seven new records of fish species for Brazil, six of which are also new records for the Amazon basin. Our results provide a valuable database for future research and conservation programs in the protected areas of the region.

Long-term influence of early human occupations on current forests of the Guiana Shield.

To decipher the long-term influences of pre-Columbian land occupations on contemporary forest structure, diversity, and functioning in Amazonia, most of the previous research focused on the alluvial plains of the major rivers of the Amazon basin. Terra firme, that is, nonflooded forests, particularly from the Guiana Shield, are yet to be explored. In this study, we aim to give new insights into the subtle traces of pre-Columbian influences on present-day forests given the archaeological context of terra firme forests of the Guiana Shield. Following archaeological prospects on 13 sites in French Guiana, we carried out forest inventories inside and outside archaeological sites and assessed the potential pre-Columbian use of the sampled tree species using an original ethnobotanical database of the Guiana Shield region. Aboveground biomass (320 and 380 T/ha, respectively), basal area (25-30 and 30-35m2 /ha, respectively), and tree density (550 and 700 stem/ha, respectively) were all significantly lower on anthropized plots (As) than on nonanthropized plots (NAs). Ancient human presence shaped the species composition of the sampled forests with Arecaceae, Burseraceae, and Lauraceae significantly more frequent in As and Annonaceae and Lecythidaceae more frequent in NAs. Although alpha diversity was not different between As and NAs, the presence of pre-Columbian sites enhances significantly the forest beta diversity at the landscape level. Finally, trees with edible fruits are positively associated with pre-Columbian sites, whereas trees used for construction or for their bark are negatively associated with pre-Columbian sites. Half a millennium after their abandonment, former occupied places from the inner Guiana Shield still bear noticeable differences with nonanthropized places. Considering the lack of data concerning archaeology of terra firme Amazonian forests, our results suggest that pre-Columbian influences on the structure (lower current biomass), diversity (higher beta diversity), and composition (linked to the past human tree uses) of current Amazonian forests might be more important than previously thought.

Three additional new genera of acidocerine water scavenger beetles from the Guiana and Brazilian Shield regions of South America (Coleoptera, Hydrophilidae, Acidocerinae).

Recent study of the water scavenger beetle subfamily Acidocerinae in the Neotropical region has uncovered numerous undescribed species that are not able to be placed in existing genera. Here, we describe three new genera to accommodate 17 of these new species from South America: Aulonocharesgen. nov. for Aulonochareslingulatussp. nov. (French Guiana, Suriname), Aulonocharesnovoairensissp. nov. (Brazil), and Aulonocharestubulussp. nov. (Brazil, Guyana, Suriname, Venezuela); Ephydrolithusgen. nov. for Ephydrolithushamadaesp. nov. (Brazil), Ephydrolithusminorsp. nov. (Brazil), Ephydrolithusogmossp. nov. (Brazil), Ephydrolithusspiculatussp. nov. (Brazil), and Ephydrolithustelisp. nov. (Brazil); and Primocerusgen. nov. for Primoceruscuspidissp. nov. (Venezuela), Primocerusgigassp. nov. (Venezuela), Primocerusneutrumsp. nov. (Guyana, Suriname, Venezuela), Primocerusocellatussp. nov. (Venezuela), Primoceruspetilussp. nov. (Brazil), Primoceruspijiguaensesp. nov. (Venezuela), Primocerusmaipuresp. nov. (Venezuela), Primocerussemipubescenssp. nov. (Guyana), and Primocerusstriatolatussp. nov. (Suriname). The genus Ephydrolithusgen. nov. is currently known to be restricted to seepages in the mountainous regions of the Brazilian Shield. Aulonocharesgen. nov. and Primocerusgen. nov. are both currently only known from the Guiana Shield, though widespread in that region where they are associated with streams and seeps. We present differential diagnoses, maps, habitat details, and illustrations of all new genera and species here described.

A Revision of Cuphea section Amazoniana s. s. (Lythraceae)

Abstract—Cuphea section Amazoniana, one of 13 sections in Cuphea, comprises 20 species, mostly narrow endemics in Colombia, Ecuador, and the Guiana Shield region of Venezuela, Guyana, French Guiana, and Brazil. The species inhabit river margins, tepuis, scrubland, savanna, and low montane forests in tropical to cold temperate climates. They are subshrubs defined by the common presence of a strigose indumentum of bifid (malpighiaceous) trichomes; small elliptic to narrowly lanceolate or linear coriaceous leaves; and tubular flowers to 9 mm long with 11 deeply inserted stamens included in the floral tube. In morphology, they are similar to or partially overlap species currently classified in Cuphea sections Trispermum and Heteranthus. The revision provides a new key, comparative morphological descriptions, first descriptions and illustrations of pollen and seed morphology, and distribution maps. Cuphea saxatilis S. A. Graham, sp. nov. from Colombia and Cuphea trisperma S. A. Graham, sp. nov. from Venezuela are newly described. Cuphea killipii Lourteig is placed in synonomy of C. philombria Lourteig. Presence or absence of a floral spur, position and shape of a nectary-like floral organ, the “disc”, and presence of two major pollen types suggest the section is not monophyletic, but consists of a minimum of two phylogenetic lineages, one in the Guiana Shield region in Venezuela and eastward, the other in low montane forests and on outliers of the Guiana Shield in Colombia and northern Ecuador. Fossilized Cuphea pollen grains resembling two types of pollen known in sect. Amazoniana, establish the presence of the genus in the Mio-Pliocene to Holocene of northern South America in areas occupied today by members of the section.

A new species of Vanilla (Orchidaceae) from the North West Amazon in Colombia

A distinctive species, Vanilla denshikoira, is described from the North West Amazon, in Colombia, within the Guiana Shield region. The species has morphological features similar to those of species in the Vanilla planifolia group. It is an important addition to the vanilla crop wild relatives, bringing the total number of species in the V. planifolia group to 21. Vanilla denshikoira is a narrow endemic, known from only a single locality, and highly vulnerable to anthropological disturbance. Under IUCN criteria it is categorized CR. The species has potential value as a non-timber forest product. We recommend a conservation program that includes support for circa situm actions implemented by the local communities.

Malakit: an innovative pilot project to self-diagnose and self-treat malaria among illegal gold miners in the Guiana Shield

BackgroundIllegal gold miners in French Guiana, a French overseas territory (‘département’) located in Amazonia, often carry malaria parasites (up to 46.8%). While the Guiana Shield Region aims at malaria elimination, the high prevalence of Plasmodium in this hard-to-reach population in conjunction with frequent incorrect use of artemisinin-based anti-malarials could favour the emergence of resistant parasites. Due to geographical and regulatory issues in French Guiana, usual malaria control strategies cannot be implemented in this particular context. Therefore, new strategies targeting this specific population in the forest are required.MethodsNumerous discussions among health institutions and scientific partners from French Guiana, Brazil and Suriname have led to an innovative project based on the distribution of kits for self-diagnosis and self-treatment of Plasmodium infections. The kit-distribution will be implemented at “resting sites”, which are areas across the border of French Guiana regularly frequented by gold miners. The main objective is to increase the appropriate use and complete malaria treatment after a positive malaria diagnosis with a rapid test, which will be evaluated with before-and-after cross-sectional studies. Monitoring indicators will be collected from health mediators at the time of kit distribution and during subsequent visits, and from illegal gold miners themselves, through a smartphone application. The project funding is multisource, including Ministries of Health of the three countries, WHO/PAHO, and the European Union.ResultsThis project will start in April 2018 as a 18 month pilot study led by the Clinical Investigation Centre of Cayenne. Results should be available at the end of 2019.DiscussionThis innovative approach may have several limitations which should be taken into account, as potential side effects, kit misuse or resale, declarative main criteria, or no Plasmodium vivax curative treatment. Close monitoring is thus needed.ConclusionsThis project may be the best available solution to a specific and important public health challenge in the Guiana Shield. If the use of self-diagnosis and self-treatment approach is effective, this strategy could be sustained by health institutions in the region.

Fish biogeography in the “Lost World” of the Guiana Shield: Phylogeography of the weakly electric knifefish Gymnotus carapo (Teleostei: Gymnotidae)

AbstractAimThe Guiana Shield region exhibits extraordinary topography that includes sheer, flat‐topped mountains (tepuis) atop an upland platform. Rivers of the eastern Pakaraima Mountains descend to Atlantic coastal lowlands, often traversing spectacular rapids and waterfalls. For fish species distributed in both uplands and lowlands, it is unclear whether these rapids and waterfalls present population or biogeographical boundaries. We sought to test this using the geographically widespread banded‐electric knifefish (Gymnotus carapo) as a model.LocationThe Guiana Shield region of South America.MethodsWe sampled 60 Gymnotus carapo specimens from the Guiana Shield region, and 75 G. carapo and closely related species from other parts of South America. We sequenced the mitochondrial cytochrome b gene and an intron from the nuclear S7 ribosomal protein gene, and used maximum likelihood and Bayesian tree‐building approaches to generate phylogenetic trees of haplotypes.ResultsHaplotype sharing is minimal between populations separated by elevational barriers. We found evidence for two main haplotype clades in the Guiana Shield: one distributed in Atlantic coastal regions that includes most lowland samples, and one inland that includes most upland samples. Inland Guiana samples are more closely related to samples from the Amazon basin than to those of Atlantic coastal regions. A single sample from Tafelberg tepui in Suriname was most closely related to the Atlantic coastal lineages.Main conclusionsRiverine barriers that result from steep elevational gradients in the Guiana Shield inhibit gene flow between uplands and lowlands, even for a widely distributed species. Biogeographical relationships of Guiana Shield G. carapo are complex, with most upland lineages showing affinities to the Amazon basin, rather than to nearby lowland drainages of the Atlantic coast.

A new disjunct Dendrothrix (Euphorbiaceae, tribe Hippomaneae): a Guiana Shield element in sub-Andean cordilleras of Ecuador and Peru.

Dendrothrix condorensis K.Wurdack, sp. nov. from the sub-Andean cordilleras of Ecuador and Peru is described and illustrated. The new species is geographically widely separated from its likely closest relative, D. yutajensis, which is endemic to the Guiana Shield region of southern Venezuela and adjacent Brazil, and notably differs in leaf morphology. Vegetative (i.e., epidermal micropapillae, trichomes) and reproductive (i.e., cymule glands, flowers, pollen) micromorphological features were examined with SEM. Rare tristaminate flowers were documented among the typical bistaminate ones. Seeds and diagnostic features among the four species of Dendrothrix are compared.