Guiana Shield Research Articles

Moho depth map of northern Venezuela based on wide-angle seismic studies

As part of the lithosphere, the crust represents Earth's rigid outer layer. Some of the tools to study the crust and its thickness are wide-angle seismic studies. To date, a series of seismic studies have been carried out in Venezuela to determine in detail the crustal thickness in the southern Caribbean, in the region of the Caribbean Mountain System in northern Venezuela, as well as along the Mérida Andes and surrounding regions. In this study, a review of the wide-angle seismic data is given, incorporating new data from the GIAME project for western Venezuela, resulting in a map of Moho depth north of the Orinoco River, which serves as the basis for future integrated models. Differences in Moho depths from seismic data and receiver function analysis are discussed. From the Caribbean plate, Moho depth increases from 20 to 25 km in the Venezuela Basin to about 35 km along the coast (except for the Falcón area where a thinning to less than 30 km is observed) and 40–45 km in Barinas - Apure and Guárico Basins, and Guayana Shield, respectively. Values of more than 50 km are observed in the Maturín Basin and in the southern part of the Mérida Andes.

New constraints for paleogeographic reconstructions at ca. 1.88 Ga from geochronology and paleomagnetism of the Carajás dyke swarm (eastern Amazonia)

The Uatumã event is a silicic large igneous province (SLIP) covering an area of 1.500.000 km2 of the Amazonia craton at ca. 1890–1850 Ma. New paleomagnetic data and U-Pb apatite ages for coeval microgranitic, andesitic, and basaltic dykes in the Carajás Province (southeastern Amazonia craton) are presented. Two primary characteristic remanent magnetizations (ChRMs) were isolated for the Carajás dykes which were combined with published results for coeval rocks in the São Felix do Xingu area, producing two grand mean poles: (1) “CA1”, dated at 1880 Ma on zircon and apatite, whose mean site directions cluster around the mean Dm = 132.8°, Im = 76° (N = 26, α95 = 5°, k = 32.7), yielding the paleomagnetic pole at 328.7°E, 23.3°S, (A95 = 8.7° K = 11.7), and (2) “CA2” from well-dated microgranitic dykes of the Velho Guilherme Suite (1855 Ma U-Pb on zircon and apatite). Site mean directions group around the mean Dm = 240.3°, Im = 11.8° (N = 18, α95 = 10.8°, k = 11.1), which yielded the paleomagnetic pole at 221.3°E, 30.2°S, (A95 = 8.8°, K = 16.2). The remanent magnetization of the Velho Guilherme microgranitic dykes is carried by pseudo-single domain (PSD) magnetite. Its primary origin is supported by a positive baked contact test. Two younger secondary components were also isolated in the Carajás dyke swarm: one probably associated to the Mesozoic Central Atlantic magmatic province (CD3), and another component (CD4) with yet undefined age. A new configuration for the Amazonia and West Africa during the Paleoproterozoic, which aligns the Sassandra shear zone (in Africa) and the North Guiana Through and other shear zones (in Guiana Shield), is supported by geological and paleomagnetic data. The large angular distance between the 1880 Ma CA1 and 1855 Ma CA2 (Q ~ 6) poles that are relatively close in age implies in a high plate velocity for the Amazonia craton, which is not consistent with modern plate tectonics. A similar large discrepancy between 1880 and 1860 Ma poles was also observed at least as many as six cratons. Although other hypotheses can be invoked, such as non-uniformitarian magnetic fields, the occurrence of large-scale true polar wander at this time may be the most parsimonious explanation of the widespread discrepancies.

Le Transport Maritime à Courte Distance du Plateau des Guyanes à la Mer des Caraïbes : la perception des parties prenantes

Ce travail de recherche a pour objectif d’analyser la perception des parties prenantes du Plateau de Guyanes a la Mer des Caraibes, concernant un service de Transport Maritime a Courte Distance (TMCD)* dans leur perimetre geographique. En effet, dans un contexte de commerce exterieur desequilibre dans les territoires concernes par ce projet, il est necessaire de developper des infrastructures et des modes de transport coherents pour les desenclaver et favoriser des echanges intra zone. En Guyane francaise, ce desequilibre est porte par le commerce d’importation essentiellement de la France metropolitaine et de l’Europe, alors qu’elle est frontaliere du Bresil – la premiere ville Macapa, capitale de l'Etat de l'Amapa se trouve a environ 700 km – et du Suriname – la capitale Paramaribo est a 330 km – avec lesquels elle entretient une cooperation economique illegale ou informelle. Cette situation est amplifiee par le fait que peu d’infrastructures existent qui pourraient faciliter des echanges organises et structures. Les dessertes maritimes interregionales etant a ces jours inexistants, notre objectif scientifique est de croiser la vision et la perception des acteurs les plus proches de cette filiere, afin de determiner si le projet de TMCD peut devenir une solution credible de transport et identifier les criteres de viabilite indispensables a sa mise en œuvre et a sa prosperite.* Notons que le Short Sea Shipping (SSS), expression anglaise traduite Transport Maritime a Courte Distance (TMCD) en francais, est aussi dite « Cabotage » par les professionnels du transport maritime.

A New Species of Alopoglossus Boulenger (1885) (Squamata, Alopoglossidae) from the Lowlands of the Eastern Guiana Shield, with Assessment of the Taxonomic Status of A. copii surinamensis

Two species of Alopoglossus (A. angulatus and A. meloi) were recognized to occur in the Guiana Shield lowlands, northeastern Amazonia. A third group of populations forming a distinct genetic lineage related to Alopoglossus avilapiresae was recently documented in the region. The Guiana Shield lowlands area also encompasses the type locality of Alopoglossus copii surinamensis (currently considered a synonym of A. angulatus). Aiming at describing a possible new species of Alopoglossus from the Guiana Shield and evaluating the taxonomic status of A. copii surinamensis, we analyzed variation in scutellation and morphometrics of the two nominal species of Alopoglossus occurring in the Guiana Shield and A. avilapiresae, which was recovered as the sister clade of the new Guiana Shield lineage, by examining 361 specimens from French Guiana, Brazil, Suriname, Guyana, Colombia, Ecuador, and Peru. Our results revealed a distinct combination of diagnostic characters that supports the description of specimens displaying the third Guiana Shield lineage as a new species. The new species is also distinct from A. copii surinamensis that we retain under a synonym of A. angulatus after examination of all species of the angulatus group and by considering updated diagnostic characters. The new taxon described here increases the total number of known species of Alopoglossus to 15.

Typification of Nietneria corymbosa (Nartheciaceae), the type of the generic name

Nietneria is the only neotropical genus of Nartheciaceae, represented by two species: N. corymbosa and N. paniculata. The collections of the brothers Moritz Richard and Robert Hermann Schomburgk in the Guiana Shield are the first records of special value for Botany, Zoology, and Mineralogy in this region. The brothers carried out an important set of botanical collections for the Guyana flora, in different periods and expeditions, which were organized in different series. Among these, the “Robert’s second collection series (Rob. ser. 2)”, corresponding to the period from 1841 to 1844, which resulted in the discovery of the genus Nietneria. In the present article, we provide a proper designation of a lectotype for Nietneria corymbosa, as a result of an ongoing monograph for the genus in Brazilian Flora 2020 Project. Along with this typification of the type of Nietneria, we provide important historical about original materials.

Rare Specimens Yield DNA to Confirm Additional Members of Tribe Stifftieae (Stifftioideae, Asteraceae) on the Guiana Highlands Tepuis

Eight of the ten genera of the Guiana Highlands shrubby Mutisieae were sequenced for the ITS and ETS of the nuclear ribosomal DNA. Results from phylogenetic analyses of the sequence data are congruent with earlier reports that support two independent introductions from different lineages of the basal Asteraceae resulting in the diversification of these taxa in the Guiana Highlands. The two clades segregated according to corolla symmetry. The five genera with bilabiate corollas, Achnopogon, Duidaea, Eurydochus, Gongylolepis and Neblinaea, were supported with members of subfamily Stifftioideae whereas those with actinomorphic corollas, Chimantaea, Stenopadus and Stomatochaeta, constitute a monophyletic group sister to Wunderlichia and strongly supported in the Wunderlichioideae. Resolution, but not statistical support, was found for relationships within the Guiana Highlands shrubby Mutisieae.

A brief history of research incampo rupestre: identifying research priorities and revisiting the geographical distribution of an ancient, widespread Neotropical biome

AbstractFew ecologists and evolutionary biologists are familiar with the ecology and evolution of the campo rupestre, an ancient azonal peinobiome characterized by a fire-prone, nutrient-impoverished, montane vegetation mosaic, home to thousands of endemics and climate refugia. With the goal of providing a synthetic view of the campo rupestre, we provide a brief historical account of the biological research, revisit its geographical distribution and identify knowledge gaps. The azonal campo rupestre is distributed as isolated and naturally fragmented sky islands, mostly in Central and Eastern Brazil and in the Guyana Shield, with significant areas across the Amazon, Cerrado, Atlantic Forest, Caatinga and Pantanal. Our proposal to elevate campo rupestre to the level of biome is expected to improve communication among scientists and consolidate the use of the term campo rupestre in the ecological and evolutionary literature, as is the case for analogous ecosystems, such as kwongan, fynbos, páramos and tepuis. Based on the identification of knowledge gaps, we propose a research programme comprising ten key topics that can foster our understanding of the ecology and evolution of campo rupestre and, potentially, support conservation strategies.

The gold, peoples and multiple frontiers of French Guiana

French Guiana is well endowed with gold like its neighbours in the Proterozoic Guiana Shield, yet it has no industrial mines, and most of the current production comes from illegal Brazilian miners. This situation is rooted in the history of its extractive frontiers, which began with the discovery of gold in 1855. French Guiana experienced two gold rushes influenced by the price of gold, first during the gold standard period, he second during the Chinese supercycle. The first wave of diverse ethnic groups searching for El Dorado came mainly from the Caribbean and Metropolitan France. Most companies did not survive the lack of infrastructure, the harsh rainforest conditions, and the end of the gold standard. After 1910, the frontier disintegrated due to the remoteness of the mine sites and the State’s inability to control the territory. The current commodity frontier is a combination of an industrial front driven by French and international investments in the Northern Belt, and an artisanal illegal infiltration of Brazilian garimpeiros moving north of the Amazonian front. The shallowness of the commodity frontier results of unfavourable environmental conditions, the sparse population relative to land, the disconnect between the Paris-driven political system.

A New Amazonian Species of the Diminutive Frog Genus Adelophryne (Anura: Brachycephaloidea: Eleutherodactylidae) from the State of Amapá, Northern Brazil

During recent field expeditions to an Amazonian region in eastern Guiana Shield (Serra do Navio, state of Amapa, northern Brazil), we collected and recorded calls of a species of Adelophryne, a diminutive leaf-litter-dwelling, direct-developing frog genus. After a careful integrative taxonomic evaluation using morphological, molecular, and bioacoustic data, we concluded that the series of specimens collected represent a new taxon, which we describe herein. The new species of Adelophryne is distinguished from all ten congeners by the following combination of character states: (1) male SVL = 12.5 mm; female SVL = 13.0–14.4 mm; (2) tympanic membrane present; (3) tympanic annulus present, incomplete; (4) vomerine teeth absent; (5) finger terminal discs absent; (6) tips of Fingers I–IV mucronate; (7) finger pads present (formula 1–1–2–1); (8) three phalanges in Finger IV; (9) dorsum smooth; (10) cloacal flap absent; (11) multi-note advertisement call composed of non-pulsed notes; (12) the call dominant frequency (4,802–5,706 Hz) coincides with the fundamental harmonic. Our study describes the eleventh species of Adelophryne, and, despite the increase in taxonomic knowledge within the past few years, there are still some species in the genus lacking a formal taxonomic description.

<p><strong><em>Epidendrum katarun-yariku</em></strong><strong> (Orchidaceae), a new species of the <em>Schistochilum</em> group from the tepuis of the Guiana Highlands in South America</strong></p>

Epidendrum katarun-yariku is hereby described and illustrated as a new species of Orchidaceae native to the summits and upper slopes of the sandstone tabletop mountains (tepuis) in the Guiana Highlands in South America.

Fluvial sand, Amazon mud, and sediment accommodation in the tropical Maroni River estuary: Controls on the transition from estuary to delta and chenier plain

The Maroni River, South America, is a tropical estuary encased in a narrow lower valley with a limited area of estuarine tidal flat development, and displays a channel with large downstream-migrating sandy bedforms linked to a large sand-filled shallow mouth. The sand-rich nature of the lower Maroni River reflects significant fluvial bedload supply, and the Maroni is among rivers with the lowest suspension-sized sediment load in the world. During the dry season, the estuary shows high suspended sediment concentrations near the bottom (several g/l) that are due to the ingress of mud streaming alongshore from the Amazon River delta. However, Amazon mud is expelled from the estuary during the high-discharge rainy-season, and seems to be essentially restricted to this seasonal intrusion along the main channel with little net estuarine sedimentation because of limited channel overbank sediment accommodation space. Sand actively supplied by the Maroni River to the coast has been diverted by wave-generated longshore transport westwards, towards the Suriname coast. This has resulted in the construction of numerous sandy cheniers within a muddy coastal plain built from Amazon mud. This sediment-source dichotomy is an important original feature of the Guiana Shield estuaries. The asymmetric progradation at the mouth of the Maroni fingerprints the westward growth, in the vicinity of river mouths, of the muddy, chenier-studded, coastal plain of the Guianas. The propensity for these rivers to supply sand to the coast, eventually evolving into deltas, depends on the ability of their estuaries to limit westward (downdrift) deflection by long-term updrift coastal sedimentation. The Maroni estuary has tended to evolve towards a delta built from both Maroni river sand and Amazon mud, a stage, among the Guiana Shield Rivers, that only the large Essequibo River estuary in Guyana has achieved. Further studies will be needed in order to constrain the infill pattern of the Maroni River estuary and its mouth.

Geopolitics of bitterness: Deciphering the history and cultural biogeography of Quassia amara L

Ethnopharmacological relevanceQuassia amara L. recently came into the spotlight in French Guiana, when it became the object of a biopiracy claim. Due to the numerous use records throughout the Guiana shield, at least since the 18th century, a thorough investigation of its origin seemed relevant and timely. In the light of the Convention on Biological Diversity (CBD) and the Nagoya protocol, questions about the origin of local knowledge are important to debate.Aim of the study: Defining cultural biogeography as the dynamics through space and time of biocultural complexes, we used this theoretical framework to shed light on the complex biogeographical and cultural history of Q. amara. We explored in particular the possible transfer of medicinal knowledge on an Old World species to a botanically related New World one by enslaved Africans in Suriname. Materials and methodsHistorical and contemporary literature research was performed by means of digitized manuscripts, archives and databases from the 17th to the 21st century. We retrieved data from digitized herbarium vouchers in herbaria of the Botanic Garden Meise (Belgium); Naturalis Biodiversity Center (the Netherlands); Missouri Botanical Garden, the Smithsonian National Museum of Natural History, the Field Museum (USA); Royal Botanic Gardens Kew (UK); the IRD Herbarium, French Guiana and the Museum National d’Histoire Naturelle (France). Vernacular names were retrieved from literature and herbarium specimens and compared to verify the origin of Quassia amara and its uses. ResultsOur exploration of digitized herbarium vouchers resulted in 1287 records, of which 661 were Q. amara and 636 were Q. africana. We observed that the destiny of this species, over at least 300 years, interweaves politics, economy, culture and medicine in a very complex way. Quassia amara's uses are difficult to attribute to specific cultural groups: the species is widely distributed in Central and South America, where it is popular among many ethnic groups. The species spread from Central to South America during the early 18th century due to political and economic reasons. This migration possibly resulted from simultaneous migration by religious orders (Jesuits) from Central America to northern South America and by Carib-speaking Amerindians (from northern South America to Suriname). Subsequently, through colonial trade networks, Q. amara spread to the rest of the world. The absence of African-derived local names in the Guiana shield suggests that Q. africana was not sufficiently familiar to enslaved Africans in the region that they preserved its names and transferred the associated medicinal knowledge to Q. amara. ConclusionsCultural biogeography has proven an interesting concept to reconstruct the dynamics of biocultural interactions through space and time, while herbarium databases have shown to be useful to decipher evolution of local plant knowledge. Tracing the origin of a knowledge is nevertheless a complex adventure that deserves time and interdisciplinary studies.

Prototype of a Low-Cost Compact Horticultural Chamber for Indoor Cultivation of Tropical Highland Wetland Flora

An environmental chamber is a specialistic device used for testing effects of given controlled conditions on a variety of objects. In case of plant growth chambers, the conditions are controlled usually for plant cultivation and propagation or botanical examination undertaken on living plant material. The aim of the project was to design and build a prototype of a desktop device with a control system capable of being used as a chamber supporting plant cultivation and propagation processes by the means of partial automation of environment control. The conditions controlled in the chamber are based on the environmental requirements of plant genera, such as Heliamphora, Drosera, Orectanthe, Cyrilla, Stegolepis, Maguireothamnus, or Utricularia. These plants occur naturally in the Guiana Highlands region of Venezuela, Brazil, and Guyana, especially around the upper parts of table-shaped mountain massifs called tepuis. The chamber was designed to simulate some of the peculiar natural factors and phenomena occurring in the high-tepui and surrounding mid-elevation wetland habitats, being the most significant for amateur-level plant cultivation, keeping the design as simple and low cost as possible. It was proven on the basis of the results of several tests made during the evaluation phase that the designed prototype of the chamber operates in a satisfying way, providing basic functionality matching the base assumptions.

Terminalia carinata Sabatier & J.Engel, sp. nov. (Combretaceae), a new large tree species from the Guiana shield revealed by re-examination of material previously identified as T. guyanensis Eichler

A new species of Terminalia L. (Combretaceae) from the Guiana shield is described as T. carinata Sabatier & J.Engel, sp. nov. based on morphological evidences. This new species was often misidentified as T. guyanensis Eichler from which it differs, as well as from other neotropical Terminalia, by its leaf undersurface palish-gray and slightly pubescent, quite long petioles and fruits with two wings wider than the body that is distinctly keeled on one face and flat on the other. An updated description of T. guyanensis is provided and the conservation status of T. carinata Sabatier & J.Engel, sp. nov. and T. guyanensis is evaluated according to IUCN criteria and a status of Least Concern (LC) is proposed for these two species.

Collections‐based systematics and biogeography in the 21st century: A tribute to Dr. Vicki Funk

Collections‐based systematics and biogeography in the 21st century: A tribute to Dr. Vicki Funk

Loricaria cuffyi (Siluriformes: Loricariidae), a new species of loricariin catfish from the Guiana Shield.

Loricaria cuffyi n. sp. is described based on 36 specimens from the Essequibo and upper Negro River drainages in western Guyana and the upper Orinoco River drainage in Venezuela. The new species can be distinguished from sympatric and geographically proximate congeners by a postorbital notch that is inconspicuous, shallow and rounded, odontode ridges on the dorsum of head and predorsal weakly developed, abdominal plates tightly joined and completely covering the median abdominal space and pectoral girdle, higher anterior lateral plate counts, and coloration characteristics. The distribution of the new species adds to an interesting and well-documented biogeographical pattern exhibited by other Guiana Shield loricariids influenced by the proto-Berbice during the Cenozoic and recent configuration of drainages in the Guiana Shield. We present an update on the taxonomy of Loricaria, and discuss the biogeography and conservation status of the new species.

Serra do Navio, Guiana Shield lowland area, Brazil: a region with high diversity of Squamata

The Guiana Region is the area bordered by the Orinoco and Negro rivers to the west, by the Amazonas River to the south and by the Atlantic Ocean to the north and east. This area is a biogeographic unit known as the Guiana Shield, with a variety of landscapes. Located in the extreme north of Brazil, in the Guiana Shield lowlands, the state of Amapa presents great diversity of habitats. In this study we provide composition and diversity data of the Squamata from Serra do Navio (SN) region, in the northeastern part of the state of Amapa, Brazil, a lowland area of the Guiana Shield. The species list was based on data obtained from herpetological collections and collection expeditions carried out at 10 sites in the municipalities of Pedra Branca do Amapari and Serra do Navio. We consider literature data from 14 sites and SN data to compare the composition of herpetofauna between the lowland and highland areas in the Brazilian Amazon. We recorded 95 species, including 57 snakes, 36 lizards, and two species of amphisbaenians. Atractus aboiporu, A. trefauti, and Erythrolamprus rochai were described from the data collected in this study. The Squamata community of SN consists mainly of diurnal lizards and nocturnal snakes, with terrestrial and cryptozoic habits, present in pristine and altered environments. The most abundant species of lizard and snake were Loxopholis guianense and Atractus latifrons, respectively. The SN region has 17 exclusive Squamata species, with a fauna similar to the Tumucumaque Mountains and northern Para sites, geographically closer regions with similar altitudes.

U–Pb geochronology, Nd–Hf isotopes, and geochemistry of Rhyacian granitoids from the Paleoproterozoic Lourenço domain (Brazil), southeastern Guiana Shield

The southern sector of the Paleoproterozoic Lourenço domain in the central-eastern region of the Amapá state, northern Brazil, consists mainly of Rhyacian granite-greenstone terranes with some Archean fragments. It is located at the transition with the Archean Amapá block, a Meso-Neoarchean continental landmass (2.85–2.60 Ga), strongly reworked during the Transamazonian orogeny (2.26–1.95 Ga). Geochemical and petrographic data together with combined zircon U–Pb and Lu–Hf (LA-ICP-MS) as well as whole-rock Sm–Nd (TIMS) dating, establish the chronology and petrogenesis of the granitoids and record the crustal growth and reworking at the transition between the Archean and Paleoproterozoic domains in the southeastern Guiana Shield. Two episodes, dated at ~2.18–2.16 Ga and 2.14–2.13 Ga, respectively, include medium-to high-K calc-alkaline and metaluminous to peraluminous rocks of the Flexal and Papa-Vento intrusive suites, emplaced in a magmatic arc environment. A third episode, dated at ~2.08 Ga, encompasses mostly peraluminous granites with a medium-to high-K calc-alkaline signature, of the syn-to late-collisional Vila Bom Jesus Suite. The zircon ƐHf (−3.5 to −4.3) and whole-rock ƐNd (−2.7 to −4.3) signatures with respective Hf-TDMC (2.9–3.1 Ga) and Nd-TDM (2.6–2.7 Ga) model ages indicate a mixture of Rhyacian juvenile material with a Mesoarchean crustal component for the magma sources of the Flexal and Papa-Vento intrusive suites. The geochemical characteristics, zircon ƐHf (−6.6 to −12.5) and whole rock ƐNd (−3.7 to −5.4) signatures, and Hf-TDMC (2.9–3.6 Ga) and Nd-TDM (2.7–2.9 Ga) model ages, together with the presence of Rhyacian (2.19 Ga) and Mesoarchean (2.82 Ga) inherited zircon crystals in the Vila Bom Jesus Suite, indicate dominant crustal reworking of Rhyacian magmatic arc rocks and Archean rocks from the adjacent Amapá Block during the arc-continent collision. The geochemical and isotopic signatures of the magmatic arc granitoids (Flexal and Papa-Vento intrusive suites) may be attributed to the incorporation in the juvenile magmatic sources of Archean continental sediments or hidden crustal fragments from the Amapá Block during the subduction processes. Geochemical affinities with continental magmatic arc and subchrondritic Hf–Nd isotopic signatures are consistent with a scenario of a long-lived Mesorhyacian (~2.20–2.13 Ga), Cordilleran-type magmatic arc setting, which evolved to a collisional setting with the amalgamation of the Archean Amapá block and the Rhyacian Lourenço domain during the Neorhyacian (2.11–2.08 Ga).

First photographic records of bush dogs (Speothos venaticus) from camera-traps in Guyana

Abstract The bush dog (Speothos venaticus) is rare, elusive, and difficult to study in the wild. Guyana contains a wealth of intact tropical forest (∼18.4 million ha) and savanna (1.6 million ha) habitats, but management of this species is hindered by a lack of data. We present two photographic records (consisting of nine individuals) of bush dogs from camera-traps set in the Kanuku Mountains Protected Area (KMPA) – the first of this species in Guyana. These records highlight the importance of Guiana Shield forests and Guyana’s expanding protected areas system to the conservation of these wide-ranging carnivores. Additionally, we recommend that detailed measurement and reporting of site variables become standard, as it will improve the efficacy of camera-trap studies of bush dogs and allow for broad-scale modelling of space use not otherwise possible due to the low detection rates at the scale of each individual study.

On Venezuelan pholcid spiders (Araneae, Pholcidae)

We present a comprehensive revision of the pholcid spider collection of M.A. González-Sponga, who between 1998 and 2011 described 22 new genera and 51 new species of Pholcidae from Venezuela. In addition, we treat the pholcid material collected during three expeditions to Venezuela conducted between 2002 and 2020. Of González-Sponga’s pholcid taxa we recognize three genera and 24 species as valid. We describe 43 new species (all from males and females) in one new and 13 previously described genera; four genera are newly recorded for Venezuela. We describe the previously unknown females of 15 species, present new records for 46 previously described species, synonymize one genus and one species, and correct numerous minor errors in previous publications on Venezuelan pholcids. At the generic level, the Venezuelan pholcid fauna now appears fairly well known, but available data on distribution and endemism suggest that many species remain undiscovered and undescribed. Despite the obvious gaps, our data are congruent with previous studies on other taxa that have the highest levels of endemism in the Venezuelan Andes, the Coastal Ranges, and the Guyana Highlands. The Falcón Region in particular shows a complex mosaic of biogeographic relationships with other regions. We provide new biological data on numerous species. We document the first cases of evolutionary microhabitat shifts in the genera Mecolaesthus Simon, 1893 and Priscula Simon, 1893. We document several cases of close congeners sharing localities, usually in slightly to conspicuously different microhabitats, sometimes apparently in identical microhabitats. We document several cases of color polymorphism, mostly intersexual, in Metagonia conica (Simon, 1893) both intersexual and among males. We document further cases of two rare phenomena in Pholcidae: use of specific non-silken structures for retreats (in Pisaboa Huber, 2000) and egg parasitism (in Priscula).