Northern Venezuela Research Articles

Using limited data to detect changes in species distributions: Insights from Amazon parrots in Venezuela

Documenting changes in distribution is necessary for understanding species’ response to environmental changes, but data on species distributions are heterogeneous in accuracy and resolution. Combining different data sources and methodological approaches can fill gaps in knowledge about the dynamic processes driving changes in species-rich, but data-poor regions. We combined recent bird survey data from the Neotropical Biodiversity Mapping Initiative (NeoMaps) with historical distribution records to estimate potential changes in the distribution of eight species of Amazon parrots in Venezuela. Using environmental covariates and presence-only data from museum collections and the literature, we first used maximum likelihood to fit a species distribution model (SDM) estimating a historical maximum probability of occurrence for each species. We then used recent, NeoMaps survey data to build single-season occupancy models (OM) with the same environmental covariates, as well as with time- and effort-dependent detectability, resulting in estimates of the current probability of occurrence. We finally calculated the disagreement between predictions as a matrix of probability of change in the state of occurrence. Our results suggested negative changes for the only restricted, threatened species, Amazona barbadensis, which has been independently confirmed with field studies. Two of the three remaining widespread species that were detected, Amazona amazonica, Amazona ochrocephala, also had a high probability of negative changes in northern Venezuela, but results were not conclusive for Amazona farinosa. The four remaining species were undetected in recent field surveys; three of these were most probably absent from the survey locations (Amazona autumnalis, Amazona mercenaria and Amazona festiva), while a fourth (Amazona dufresniana) requires more intensive targeted sampling to estimate its current status. Our approach is unique in taking full advantage of available, but limited data, and in detecting a high probability of change even for rare and patchily-distributed species. However, it is presently limited to species meeting the strong assumptions required for maximum-likelihood estimation with presence-only data, including very high detectability and representative sampling of its historical distribution.

Área de acción del chigüiro (Hydrochoerus isthmius) en un sistema agropecuario en Córdoba, Colombia

El chigüiro es autóctono del continente americano; en Colombia se encuentran dos especies: Hydrochoerus hydrochaeris, con distribución en los Llanos Orientales de Colombia y Amazonas colombiano (también distribuido en Argentina, Paraguay, Ecuador, Venezuela, Brasil, Perú, Bolivia, las Guyanas); e Hydrochoerus isthmius, que habita al norte de Colombia, Panamá y Venezuela, aislada por los Andes de Mérida y la Serranía del Perijá. Este estudio buscó conocer el área de acción de H. isthmius, en paisajes ganaderos de Córdoba, al noroccidente de Colombia. Durante el período de marzo y mayo de 2007, dentro de predios ganaderos del municipio de Valencia, departamento de Córdoba, Colombia, se realizaron trabajos de seguimiento a individuos de dos grupos de una población de chigüiros. Se utilizó la técnica de radio-seguimiento usando cuatro animales previamente radio-marcados. Se encontró que el área de acción de H. isthmius en paisajes de ganadería extensiva de Valencia, presenta una mayor área de acción durante la época seca (1,93±0,88 ha), comparada con la época de lluvias (0,47±0,32 ha) en contraste con áreas de acción descritos en otros trabajos de H. hydrochaeris con reportes de áreas de uso que varían desde 5,5±10,8 ha hasta 44 (10-56) ha, H. isthmius presenta áreas de acción más pequeños (1,20±1,0 ha).

Depredación de un ratón colicorto achocolatado (Necromys urichi) por una pavita ferruginea (Glaucidium brasilianum) en la Cordillera de la Costa de Venezuela

Reportamos un evento de depredación de un ratón colicorto achocolatado (Necromys urichi) por una pavita ferruginea (Glaucidium brasilianum) en la Cordillera de la Costa, al norte de Venezuela. Dicho evento consistió en la observación de un individuo de G. brasilianum posado sujetando con ambas patas un ejemplar de N. urichi, el cual ya había sido decapitado y parcialmente consumido. Glaucidium brasilianum se alimenta de insectos y vertebrados pequeños, y es capaz de capturar y consumir presas como aves y mamíferos que los superan en tamaño. En vista del comportamiento de G. brasilianum y de la alta abundancia que N. urichi exhibe en los ecosistemas montanos de la Cordillera de la Costa, es probable que este roedor represente un importante componente en la dieta de este búho, de cuyas poblaciones neotropicales se conoce muy poco.

On the Origin of Pantepui montane biotas: A Perspective Based on the Phylogeny of Aulacorhynchus toucanets.

To understand the origin of Pantepui montane biotas, we studied the biogeography of toucanets in the genus Aulacorhynchus. These birds are ideal for analyzing historical relationships among Neotropical montane regions, given their geographic distribution from Mexico south to Bolivia, including northern Venezuela (Cordillera de la Costa), and the Pantepui. Analyses were based on molecular phylogenies using mitochondrial and nuclear DNA sequences. Topology tests were applied to compare alternative hypotheses that may explain the current distribution of Aulacorhynchus toucanets, in the context of previous hypotheses of the origin of Pantepui montane biotas. Biogeographic reconstructions in RASP and Lagrange were used to estimate the ancestral area of the genus, and an analysis in BEAST was used to estimate a time framework for its diversification. A sister relationship between the Pantepui and Andes+Cordillera de la Costa was significantly more likely than topologies indicating other hypothesis for the origin of Pantepui populations. The Andes was inferred as the ancestral area for Aulacorhynchus, and the group has diversified since the late Miocene. The biogeographic patterns found herein, in which the Andes are the source for biotas of other regions, are consistent with those found for flowerpiercers and tanagers, and do not support the hypothesis of the geologically old Pantepui as a source of Neotropical montain diversity. Based on the high potential for cryptic speciation and isolation of Pantepui populations, we consider that phylogenetic studies of additional taxa are important from a conservation perspective.

The Bananaquit, a Neotropical passerine nectar feeding bird, has a high protein requirement relative to other nectarivorous birds

For nectar-feeding birds, the low amino acid and protein content of nectar is likely a major nutritional constraint. Nectar-feeding birds present morphological, behavioral, and physiological adaptations that allow them to exploit nectar efficiently. One of these adaptations might be a low nitrogen requirement compared to birds of taxa that rely on other resources. The Bananaquit (Coereba flaveola) is considered a specialized nectar-feeding passerine. It is widely distributed in the Neotropics and one of the most abundant flower-visiting passerine in northern Venezuela. We measured maintenance nitrogen requirement (MNR) and total endogenous nitrogen loss (TENL) in captive Bananaquits fed on four diets of varying concentrations of protein (0, 1.5, 3.0, and 7.0 %). We found that the Bananaquit had a MNR of 8.7 mg N day–1 (313.2 mg N W–0.75 day–1) and a TENL of 3.3 mg N day–1 (111 mg N W–0.75 day–1), values in the high range of what was previously reported for other nectar-feeding birds. However, when compared to other species with different feeding habits (i.e. granivores) the Bananaquit presents a low nitrogen requirement. These high values suggest different physiological and behavioral strategies from other nectar-feeding birds or methodological issues associated to an unbalanced diet based on a protein plant source.

Brazilian marsupial frogs are diphyletic (Anura: Hemiphractidae: Gastrotheca)

Molecular phylogenetic analyses based on expanded taxonomic and geographic sampling support the monophyly of the marsupial frog genera (family Hemiphractidae), resolve six geographically circumscribed lineages within Gastrotheca, and, for the first time, reveal that two divergent lineages of Gastrotheca inhabit the Atlantic Coastal Forests of Brazil. Within Gastrotheca, the earliest diverging clade is confined to northeastern Brazil, whereas the three subsequent diverging lineages are restricted to northern Venezuela (G. walkeri), southeastern Brazil, and northwestern South America. All species in these clades inhabit humid forests at low to mid-elevations, and their life histories are characterized by lacking free-living tadpoles (i.e., direct development). Two derived clades inhabit the Andes, and both contain species with either direct development or tadpoles. One Andean clade of Gastrotheca ranges in the high Andes from Colombia to extreme northern Peru, whereas the other clade inhabits high elevations in the Andes of southern Ecuador, Peru, and Bolivia, and lower elevations in the Andes of northwestern Argentina. The presence of two non-sister lineages on each side of the Amazon Basin suggests that vicariance across this central region played an important role in diversification within Gastrotheca.

A new anisophyllous species of <i>Miconia</i> (Melastomataceae: Miconieae) from the Coastal Cordillera in northern Venezuela

Miconia longidentata , a new species of Melastomataceae, Miconieae, from the Coastal Cordillera in northern Venezuela is described. This species is known from cloud and mid elevation forests in the Waraira Repano National Park (formerly known as Avila National Park). Miconia longidentata is characterized by sessile to sub-sessile, dimorphic leaves, short axillary inflorescences, and four-merous flowers with long calyx teeth. By its character combination Miconia longidentata would have been described as Clidemia , but it is here described in Miconia due to ongoing taxonomic realignments in the Miconieae. The new species is compared to putative relatives, and a list of anisophyllous species traditionally placed in Clidemia is provided. A list of species of Melastomataceae endemic to the Coastal Cordillera in northern Venezuela is also included.

Potential geographical distribution of the red palm mite in South America

Among pests that have recently been introduced into the Americas, the red palm mite, Raoiella indica Hirst (Prostigmata: Tenuipalpidae), is the most invasive. This mite has spread rapidly to several Caribbean countries, United States of America, Mexico, Venezuela, Colombia and Brazil. The potential dispersion of R. indica to other regions of South America could seriously impact the cultivation of coconuts, bananas, exotic and native palms and tropical flowers such as the Heliconiaceae. To facilitate the development of efficacious R. indica management techniques such as the adoption of phytosanitary measures to prevent or delay the dispersion of this pest, the objective of this paper was to estimate the potential geographical distribution of R. indica in South America using a maximum entropy model. The R. indica occurrence data used in this model were obtained from extant literature, online databases and field sampling data. The model predicted potential suitable areas for R. indica in northern Colombia, central and northern Venezuela, Guyana, Suriname, east French Guiana and many parts of Brazil, including Roraima, the eastern Amazonas, northern Pará, Amapá and the coastal zones, from Pará to north of Rio de Janeiro. These results indicate the potential for significant R. indica related economic and social impacts in all of these countries, particularly in Brazil, because the suitable habitat regions overlap with agricultural areas for R. indica host plants such as coconuts and bananas.

The Pleistocene Glyptodontidae Gray, 1869 (Xenarthra: Cingulata) of Colombia and some considerations about the South American Glyptodontinae

Until recently, one well-characterized Pleistocene genus of the subfamily Glyptodontinae (Glyptodon ca. 1.08-0.0011 My) was recognized in South America. In recent times, some authors have demonstrated, through the re-analysis of material originally classified as Glyptodon Owen and Hoplophorus Lund, the presence of a second species belonging to the North American glyptodontine Glyptotherium Osborn (ca. 58-12 ky BP), currently known from in Venezuela and Brazil. This situation implies the need for a new study, with modern taxonomical criteria, of those materials belonging to the Glyptodontinae, particularly in those territories where the knowledge of these taxa is scarce. Presented here is a new analysis of the Pleistocene Glyptodontidae from Colombia, including some taxonomic and paleobiogeographic remarks. The results show that the only reported Glyptodontidae specimens in Colombia belong to Glyptodon sp. In turn, the evidence suggests that only one single species of Glyptotherium is present in South America, currently assigned to Glyptotherium cf. Gl. cylindricum. However, a more accurate analysis is necessary to confirm or refute this taxonomic identification. To date, Glyptotherium present has been found only in an area parallel to the Caribbean Sea and the Atlantic Ocean (northern Venezuela and eastern Brazil), up to 20°S, and is always linked to lowlands. This geographic distribution agrees with the proposition of an eastern corridor during the Great American Biotic Interchange. Below this latitude, the only recorded glyptodontine corresponds to Glyptodon, which is also recorded in a strip parallel to the Cordillera de Los Andes reaching Colombia and Venezuela. Taking into account this distribution, the presence of this genus in Central America cannot be discarded.

Faunal nestedness and species–area relationship for small non-volant mammals in “sky islands” of northern Venezuela

We study the biogeography of small non-volant mammals in mesic montane sky islands of northern Venezuela. Fieldwork, examination of museum specimens, and critical use of literature yielded species lists for the Cordillera de Mérida, Cordillera de la Costa, Serranía de San Luis, and Cerro Santa Ana. Fieldwork confirmed the species known from Cerro Santa Ana and added 12 species for the Serranía de San Luis. Richness decreases with smaller area. Furthermore, the faunas are highly nested, with taxa dropping out at successive depressions. Species deviating from nestedness provide a signal indicative of in situ speciation in rodents but not in marsupials.

Trypanosoma evansi kDNA minicircle found in the Venezuelan nectar-feeding bat Leptonycteris curasoae (Glossophaginae), supports the hypothesis of multiple origins of that parasite in South America

Trypanosoma evansi is a mammal generalist protozoon which causes negative effects on health and productivity in bovine and equine herds in South America, Europe, Asia and Africa. By molecular methods, we screened the presence of that parasite together with other trypanosome species in 105 bats of 10 species collected in arid zones of northern Venezuela. The first molecular approach was fluorescent fragment length barcoding (FFLB), which relies on amplification of relative small regions of rRNA genes (four loci) and fluorescence detection. By FFLB, 17 samples showed patterns of possible trypanosomatid infections. These samples were used to test presence of trypanosomes by PCR using the following DNA markers: V7–V8 SSU rRNA, gGAPDH and kDNA minicircle regions. Only in one individual of the nectar-feeding bat, Leptonycteris curasoae, we were able to amplify 1000bp of the trypanosome kDNA minicircle. That PCR product was sequenced and the parasite species was determined by NCBI-BLAST and phylogenetic analysis. Both analyses showed that the minicircle sequence corresponds to Trypanosoma evansi. The phylogenetic analysis of the sequence obtained in this study clustered with a T. evansi sequence obtained in a Venezuelan capybara, Hydrochoerus hydrochaeris, and distant of others two T. evansi sequences obtained in a Colombian capybara and horse. This result supports the hypothesis of multiple origins of T. evansi in South America.

Climate change impacts on the future distribution of date palms: a modeling exercise using CLIMEX.

Climate is changing and, as a consequence, some areas that are climatically suitable for date palm (Phoenix dactylifera L.) cultivation at the present time will become unsuitable in the future. In contrast, some areas that are unsuitable under the current climate will become suitable in the future. Consequently, countries that are dependent on date fruit export will experience economic decline, while other countries’ economies could improve. Knowledge of the likely potential distribution of this economically important crop under current and future climate scenarios will be useful in planning better strategies to manage such issues. This study used CLIMEX to estimate potential date palm distribution under current and future climate models by using one emission scenario (A2) with two different global climate models (GCMs), CSIRO-Mk3.0 (CS) and MIROC-H (MR). The results indicate that in North Africa, many areas with a suitable climate for this species are projected to become climatically unsuitable by 2100. In North and South America, locations such as south-eastern Bolivia and northern Venezuela will become climatically more suitable. By 2070, Saudi Arabia, Iraq and western Iran are projected to have a reduction in climate suitability. The results indicate that cold and dry stresses will play an important role in date palm distribution in the future. These results can inform strategic planning by government and agricultural organizations by identifying new areas in which to cultivate this economically important crop in the future and those areas that will need greater attention due to becoming marginal regions for continued date palm cultivation.

Geographic distribution and host plants of Raoiella indica and associated mite species in northern Venezuela

The red palm mite (RPM), Raoiella indica Hirst (Acari: Tenuipalpidae), is an invasive pest in the New World, where it is currently considered a serious threat to coconut and banana crops. It was first reported from northern Venezuela in 2007. To determine its current distribution in this country, surveys were carried out from October 2008 to April 2010 on coconut (Cocos nucifera L.), banana (Musa spp.), ornamental plants and weeds in northern Venezuela. Higher population levels of RPM were registered on commercial coconut farms in Falcón and Sucre states but also on other plant species naturally growing along the coastal line in Anzoategui, Aragua, Carabobo, Monagas and Nueva Esparta states. Out of 34 botanical species evaluated, all RPM stages were observed only on eight arecaceous, one musaceous and one streliziaceous species, indicating that the pest developed and reproduced only on these plants. Mite specimens found on weeds were considered spurious events, as immature stages of the pest were never found on these. Amblyseius largoensis (Muma) (Acari: Phytoseiidae) was the most frequent predatory mite associated with RPM in all sampling sites. The results indicate that RPM has spread to extensive areas of northern Venezuela since its initial detection in Güiria, Sucre state. Considering the report of this pest mite in northern Brazil in the late 2009, additional samplings in southern Venezuela should be carried out, to evaluate the possible presence of RPM also in that region.

Systematics of the Dendrophidion nuchale complex (Serpentes: Colubridae) with the description of a new species from Central America

We review the systematics of the Dendrophidion nuchale complex in Central America and northern South America andrecognize three species. The names D. nuchale (W. Peters) and D. clarkii Dunn apply to two of the species. The third isdescribed as a new species, D. rufiterminorum. It differs from D. clarkii and D. nuchale in coloration and hemipenial char-acters but all three species of the nuchale complex are very similar in scutellation characters. Dendrophidion nuchale isdistributed in the coast ranges and adjacent foothills of northern Venezuela, and in a seemingly disjunct population in theSerranía de Perijá in western Venezuela. The name clarkii was recently applied to all populations of the nuchale complexfrom Belize and Guatemala in the north to western Colombia and Ecuador in the south. Herein, we restrict the name D.clarkii to populations in lower Middle America (Costa Rica and Panama) and west of the Andes in Colombia and Ecuador.Dendrophidion rufiterminorum is distributed in northern Central America (Belize, Guatemala, northern Honduras) fol-lowed by a broad disjunction without records of the species throughout most of Honduras and Nicaragua; thereafter, a fewspecimens and photographs document the presence of D. rufiterminorum on the Caribbean versant of southern Nicaraguaand Costa Rica, and uplands of northwestern Costa Rica (Pacific versant). Two localities of sympatry between D. rufiter-minorum and D. clarkii are known in Costa Rica (one on the Atlantic versant, the other on Pacific versant). Nonetheless,there is sparse documentation of either species in Costa Rica. The populations referred to D. clarkii in southwestern CostaRica, the eastern half of Panama, and western Colombia and Ecuador need further study. Hemipenes of species of thenuchale complex are described. All three species have a pair of enormously enlarged sulcate spines and a regular lineararray of enlarged spines (spinose annulus) encircling the base of the apical region. These characters are also shared with D. dendrophis sensu lato but not other members of the dendrophis species group.

Grimsdalea magnaclavata Germeraad, Hopping & Muller: an enigmatic pollen type from the Neogene of northern South America

Grimsdalea magnaclavata was first described by Germeraad, Hopping and Muller from Miocene and Pliocene deposits of northern South America, specifically Colombia and Venezuela. The specific epithet, ‘magnaclavata', was selected by the authors to draw attention to the distinctive clavate processes of the pollen. A revised taxonomic description is supported by illustrations of fossil specimens from outcrop and well sections that show the range in morphology not previously recorded in the original description; the key difference is the wide variation in process morphology from clavae to clavae with interspersed echinae. Based on the new observations of the pollen morphology we conclude that the records from Cretaceous and Paleogene sediments in North and West Africa are invalid. G. magnaclavata is clearly restricted to northern South America from the Miocene to Pleistocene. The parent plant of G. magnaclavata probably grew in upper coastal plain or around swamps, commonly associated with shrubs and herbaceous savannah plants. The botanical affinity of G. magnaclavata has always been in question. Based on a review of pollen from several palm genera presently extant in northern South America we consider that the nearest living relatives, if indeed G. magnaclavata is an ancient palm, are the genera Mauritia and Mauritiella. The basis for this conclusion is the distinctive foot layer morphology of the processes in the fossil and the modern examples.

Diversity of avian haemosporidians in arid zones of northern Venezuela

Arid zones of northern Venezuela are represented by isolated areas, important from an ornithological and ecological perspective due to the occurrence of restricted-range species of birds. We analysed the prevalence and molecular diversity of haemosporidian parasites of wild birds in this region by screening 527 individuals (11 families and 20 species) for parasite mitochondrial DNA. The overall prevalence of parasites was 41%, representing 17 mitochondrial lineages: 7 of Plasmodium and 10 of Haemoproteus. Two parasite lineages occurred in both the eastern and western regions infecting a single host species, Mimus gilvus. These lineages are also present throughout northern and central Venezuela in a variety of arid and mesic habitats. Some lineages found in this study in northern Venezuela have also been observed in different localities in the Americas, including the West Indies. In spite of the widespread distributions of some of the parasite lineages found in northern Venezuela, several, including some that are relatively common (e.g. Ven05 and Ven06), have not been reported from elsewhere. Additional studies are needed to characterize the host and geographical distribution of avian malaria parasite lineages, which will provide a better understanding of the influence of landscape, vector abundance and diversity, and host identity on haemosporidian parasite diversity and prevalence.

Ophiolite-Related Ultramafic Rocks (Serpentinites) in the Caribbean Region: A Review of their Occurrence, Composition, Origin, Emplacement and Ni-Laterite Soil Formation

Ultramafic rocks, mainly serpentinized peridotites of mantle origin, are mostly associated with the ophiolites of Mesozoic age that occur in belts along three of the margins of the Caribbean plate. The most extensive exposures are in Cuba. The ultramafic-mafic association (ophiolites) were formed and emplaced in several different tectonic environments. Mineralogical studies of the ultramafic rocks and the chemistry of the associated mafic rocks indicate that most of the ultramafic-mafic associations in both the northern and southern margins of the plate were formed in arc-related environments. There is little mantle peridotite exposed in the ophiolitic associations of the west coast of Central America, in the south Caribbean in Curacao and in the Andean belts in Colombia. In these occurrences the chemistry and age of the mafic rocks indicates that this association is mainly part of the 89 Ma Caribbean plateau province. The age of the mantle peridotites and associated ophiolites is probably mainly late Jurassic or Early Cretaceous. Emplacement of the ophiolites possibly began in the Early Cretaceous in Hispaniola and Puerto Rico, but most emplacement took place in the Late Cretaceous to Eocene (e.g. Cuba). Along the northern South America plate margin, in the Caribbean mountain belt, emplacement was by major thrusting and probably was not completed until the Oligocene or even the early Miocene. Caribbean mantle peridotites, before serpentinization, were mainly harzburgites, but dunites and lherzolites are also present. In detail, the mineralogical and chemical composition varies even within one ultramafic body, reflecting melting processes and peridotite/melt interaction in the upper mantle. At least for the northern Caribbean, uplift (postemplacement tectonics) exposed the ultramafic massifs as a land surface to effective laterization in the beginning of the Miocene. Tectonic factors, determining the uplift, exposing the peridotites to weathering varied. In the northern Caribbean, in Guatemala, Jamaica, and Hispaniola, uplift occurred as a result of transpresional movement along pre-existing major faults. In Cuba, uplift occurred on a regional scale, determined by isostatic adjustment. In the south Caribbean, uplift of the Cordillera de la Costa and Serrania del Interior exposing the peridotites, also appears to be related to strike-slip movement along the El Pilar fault system. In the Caribbean, Ni-laterite deposits are currently being mined in the central Dominican Republic, eastern Cuba, northern Venezuela and northwest Colombia. Although apparently formed over ultramafic rocks of similar composition and under similar climatic conditions, the composition of the lateritic soils varies. Factors that probably determined these differences in laterite composition are geomorphology, topography, drainage and tectonics. According to the mineralogy of principal ore-bearing phases, Dominican Ni-laterite deposits are classified as the hydrous silicate-type. The main Ni-bearing minerals are hydrated Mg-Ni silicates (serpentine and “garnierite”) occurring deeper in the profile (saprolite horizon). In contrast, in the deposits of eastern Cuba, the Ni and Co occurs mainly in the limonite zone composed of Fe hydroxides and oxides as the dominant mineralogy in the upper part of the profile, and are classified as the oxide-type.

Mercury biomagnification in the food web of a neotropical stream

Anthropogenic and natural mercury (Hg) contamination have been a major concern in South America since the early 1900s, but it remains unclear whether Hg levels pose a hazard to human health in regions that lack point sources. We studied Hg biomagnification patterns in the food web of Río Las Marías, an Andean piedmont stream in northern Venezuela, which supports a major subsistence fishery. Mercury concentrations and trophic positions in the food web (based on stable isotopes of nitrogen and carbon) were characterized for 24 fish species representing seven trophic guilds (piscivore, generalized carnivore, omnivore, invertivore, algivore, terrestrial herbivore, detritivore). Mercury showed significant biomagnification through the food web, but vertical trophic position explained little of the variation. Muscle Hg concentrations also increased with body mass across the food web. Trophic guild assignments offered a useful alternative to explicit analysis of vertical trophic position; piscivores showed the highest Hg concentrations and terrestrial herbivores had the lowest. There were no consistent seasonal differences in Hg concentrations within the 5 species sampled during both the wet and dry seasons, suggesting that bioavailability is unaffected by strong seasonal variation in rainfall. From a human health perspective, many medium- to large-bodied species that are commonly eaten had Hg concentrations that exceeded International Marketing Limit (IML) (0.5μg/g) and World Health Organization (WHO) guidelines (0.2μg/g) for consumption. We conclude that Hg concentrations may pose a health concern for local subsistence fishermen and their families. Our results suggest a need to perform risk assessment and better understand contaminant levels in subsistence and commercial fisheries even in areas that lack known Hg point sources.

Anacroneuria spp. (Insecta: Plecoptera: Perlidae) as paratenic hosts of Pheromermis sp. (Nematoda: Mermithidae) in Venezuela

Nematodes of the family Mermithidae are known as endoparasites of freshwater arthropods. Juveniles of Pheromermis sp. (Mermithidae) were found coiled inside stonefly nymphs collected at seven sites in the Guare and Emilia rivers in northern Venezuela. Prevalence in Anacroneuria blanca was 93.2% () and in A. caraca was 91.5% (). In A. blanca, a higher number of juveniles per individual host was observed than in A. caraca, a fact that is probably related to body size. Although parasites were observed in all body regions, the highest incidence occurred in the legs and thorax. Considering the nematode prevalence and intensity of parasitism, we consider individuals of Anacroneuria spp. to be important hosts of Pheromermis in these rivers.

Introduction: New World Primates

With an evolutionary history dating back 30 million years, the Neotropical primates now present a remarkable radiation of monkeys, comprising some 200 extant taxa (c. 150 species), and ranging in size from the smallest anthropoid, the Pygmy marmoset Cebuella pygmaea at c. 100 g, to the muriquis (Brachyteles) and spider monkeys (Ateles) weighing more than 10 kg. They occur throughout the American tropics – the Mexican spider monkey Ateles geoffroyi just north of the Tropic of Cancer, and the Southern brown howler Alouatta guariba extends some distance south of the Tropic of Capricorn to (31°S), where the Atlantic forest gives way to the Pampas. There are three biogeographic communities for these primates, each having considerable endemism: (1) southern Mexico, Central America, and central and northern Colombia and Venezuela, with 45 taxa (spp and subspp); (2) the Amazon basin, including the Guianas and the eastern slopes of the Andes, with 135 taxa (spp and subspp); (3) the non-Amazonian tropical savannah (Cerrado), dry forests in north-east Brazil (Caatinga), southern Bolivia and Paraguay, the Chaco, and the lowland, montane, evergreen and semi-deciduous Atlantic forest in Brazil, Paraguay and Argentina, with 31 taxa (spp and subsp). Rosenberger (1992, 2011) neatly summarized the four principal adaptive zones of these primates using an ‘ecophylogenetic model’ of size, diet and locomotion. The first is occupied by the Callitrichidae (marmosets, Goeldi’s monkey Callimico goeldii, lion tamarins and tamarins); small (100–750 g) insectivore-frugivore-exudativores of the middle to lower canopy and understorey of the forest. They have specific adaptations for moving about on tree trunks, for vertical clinging and leaping (extreme in Pygmy marmosets and Goeldi’s monkey) and, in the