The Entolomataceae of the Pakaraima Mountains of Guyana III: new species of Rhodocybe

Rhodocybe pruinosostipitata, found on woody debris, and R. spongiosa, found on soil litter, are described as new species from tropical rainforests of the Pakaraima Mountains of Guyana. Both species possess pustulate basidiospores and pseudocystidia. Rhodocybe pruinosostipitata is classified in section Rhodocybe based on its centrally attached stipe, pleurocystidia as pseudocystidia with brightly colored contents, and lack of clamp connections. Rhodocybe spongiosa is classified in section Crepidotoides based on its pleurotoid stature and hymenial pseudocystidia. Macromorphological, micromorphological, and habitat data are provided for the new species.     

Biogeography of the Primates of Guyana: Effects of Habitat Use and Diet on Geographic Distribution

Species that exploit a wide range of resources or habitats (generalists) tend to be widely distributed, whereas species that exploit a narrow range of resources or habitats (specialists) often have a limited distribution. The distribution patterns are thought to result from specialists using relatively smaller habitats than those exploited by generalists. I used data from 1,725 km of primate surveys that I conducted in Guyana to test these hypotheses. Habitat breadth is the total number of different habitat types occupied by each species. I used the total number of different food categories exploited by each species to measure dietary breadth. Geographic range size is correlated with habitat breadth but not with dietary breadth or body size for the 8 primate species in Guyana. Habitat generalists—red howlers and wedge-capped capuchins—range into all habitats. Habitat specialists—spider monkeys, brown bearded sakis, and golden-handed tamarins—range only into large habitats. Habitat generalists tend to be dietary type specialists in Guyana. I suggest that only habitat generalists can subsist on the low-quality foods in small habitats in Guyana. Conversely, habitat specialists tend to be dietary type generalists in Guyana. They must feed on a variety of food types in large habitats. However, using the number of food categories exploited as a measure of dietary breadth may be only a weak aspect of multidimensional niche. Researchers testing biogeographic hypotheses associated with dietary breadth should consider including multivariate indicators of both the types of food categories eaten and the number of plant species exploited.     

Molecular phylogenetics of Atlantic Shield Platynectes diving beetles (Coleoptera: Dytiscidae): a first glance at the evolution of the genus in the Amazon Basin

Neotropical diving beetles of the genus Platynectes are distributed across Central America, the Andes and different Precambrian shields in the Amazon Basin. Species from the northern Guiana Shield form a monophyletic clade, yet the phylogenetic relationships of the eastern Atlantic Shield species remain unknown. Here, we augmented an existing molecular dataset with a species from the Atlantic Shield that was not previously sampled. We reconstructed the phylogenetic relationships and estimated divergence times to understand the evolution of lineages dwelling in this region. The newly sampled specimens from the Atlantic Shield are recovered as sister taxa to Guiana Shield species. The dating analyses suggest a split between these two lineages in the late Oligocene to mid-Miocene, contemporary with the Miocenic geological remodeling of the Amazon Basin. Additional sampling in the Atlantic and Central Brazilian Shields will be determinant to test the monophyly of Platynectes species distributed in these ancient shields, and to fully understand the biogeographical history of diving beetles in the Amazon Basin.     

Phytogeography of Lusitanian Macaronesia: biogeographic affinities in species richness and assemblage composition

Analysis of biogeographic affinities is a key tool to establish and improve the resolution of hierarchical biogeographic systems. We describe patterns of species richness of the marine macroalgal flora across Lusitanian Macaronesia (Azores, Madeira, the Salvage Islands and the Canary Islands), and test (i) whether such differences are related to differences in proximity to the nearest continental shore and size among islands. We also explore biogeographic affinities in the composition of macroalgal assemblages (= presence/absence of each taxon in multivariate datasets) to determine (ii) whether each archipelago is a biogeographic unit within this ecoregion and (iii) whether patterns in assemblage composition are related to proximity (i.e. distances) among islands. Presence/absence matrices were created to test and visualize multivariate affinities among archipelagos. A total of 872 taxa were compiled. Species richness peaked at the Canary Islands and decreased towards the Azores; the pattern matched a progressive increase in distance from the nearest continental shores, matching the classical island biogeography theory. Intra-archipelago differences in species richness were largely related to variations in island size. Biogeographic similarities among archipelagos were hierarchically structured. Madeira and the Salvage Islands constituted one biogeographic unit. Floras from the Azores, Madeira and the Salvage Islands were barely separable from each other, but were different from those at the Canary Islands. Such biogeographic similarities among islands were negatively correlated with the geographical separation (i.e. distances) among them. Proximity to nearby continental shores, in conjunction with large- and meso-scale oceanographic patterns, seems to interact to create patterns in richness and composition of algal assemblages across Lusitanian Macaronesia.     

New <Emphasis Type="Italic">Clavulina</Emphasis> species from the Pakaraima Mountains of Guyana

Five new species of Clavulina (Clavulinaceae, Cantharellales, Basidiomycota) are described from the Pakaraima Mountains of Guyana, occurring in rain forests dominated by the ectomycorrhizal tree Dicymbe corymbosa (Caesalpiniaceae). These clavarioid fungi have simple (i.e., unbranching) basidiomata, which is a relatively uncommon phenotypic feature for the genus Clavulina. Macromorphological, micromorphological, and habitat data are provided for each taxon, and nuclear ribosomal DNA sequences of the 28S subunit and internal transcribed spacer region were obtained for each holotype collection.     

Upland Soil Charcoal in the Wet Tropical Forests of Central Guyana

A soil charcoal survey was undertaken across 60,000 ha of closed-canopy tropical forest in central Guyana to determine the occurrence, ubiquity, and age of past forest fires across a range of terra firme soil types. Samples were clustered around six centers consisting of spatially nested sample stations. Most charcoal was found between 40 and 60 cm depth with fewest samples yielding material at 0–20 cm depth. The first core yielded charcoal at most stations. Charcoal ages of a random subsample ranged from less than 200 YBP to 9500 YBP with a noticeable peak between 1000 and 1250 YBP. Results reinforce a view that most closed-canopy tropical forests in eastern Amazonia have been subject to palaeo-fire events of unknown severity with a peak in charcoal age consistently appearing between 1000 and 2000 YBP. The two samples dated to the early Holocene represent some of the oldest indicators of paleo-fire known from upland Neotropical forest soils. Ubiquitous soil charcoal in central Guyana further indicate both forest resilience to fire and the widespread propensity for regional forests to burn, particularly during anomalous periods of drought.     

Mast fruiting and seedling survival of the ectomycorrhizal, monodominant Dicymbe corymbosa (Caesalpiniaceae) in Guyana

In Guyana, we investigated seed output, and resulting seedling establishment and survival, during a 'mast' year, by the ectomycorrhizal, monodominant rainforest canopy tree Dicymbe corymbosa (Caesalpiniaceae), a species with high, synchronous seed production at intermittent years. By utilizing seed traps, the mast seed output, predation, carbon and mineral investment, and masting synchrony were quantified in 2003 in primary D. corymbosa forests. Establishment of seedling cohorts was monitored, and climatic conditions associated with masting were assessed. During 2003, D. corymbosa in the Pakaraima Mountains exhibited high, synchronous seed production with low dispersal and predation. Investment in reproductive biomass was large relative to that in other tropical forests. Recent D. corymbosa reproductive events followed El Nino-induced droughts, with little intervening seed production. Over 12 months, 40% of the 2003 seedling cohort survived. Our results suggest that D. corymbosa has a strongly bimodal fruiting pattern that allows the establishment of a large seedling bank, facilitating persistent monodominance. Resource investment in large seed crops may depend on mineral recycling via ectomycorrhizas, coupled with the reallocation of carbon from vegetative maintenance.     

Geographical affinities of the Cape flora, South Africa

Aim The flora characteristic of the Cape Floristic Region (CFR) is dominated by a relatively small number of clades that have been proposed as ‘Cape clades’. These clades have variously been suggested to have African or Austral affinities. Here we evaluate the support for these conflicting hypotheses. In addition, we test the hypothesis that these clades share a common time of differentiation from their geographical neighbours. Location The Cape Floristic Region, South Africa Methods We use both published and unpublished phylogenetic information to investigate the geographical sister areas of the Cape clades as well as the timing and the direction of biogeographical disjunctions. Results Almost half of the Cape clades for which unambiguous sister areas could be established show a trans‐Indian Ocean disjunction. The earliest trans‐Indian Ocean disjunction dates from 80 Ma. Other disjunctions date from various times in the Cenozoic, and we suggest that the process of recruiting lineages into the Cape flora might be ongoing. Relatively few Cape clades show a sister relationship with South America and tropical Africa, despite their relative geographical proximity. Numerous Cape clades contain species also found on tropical African mountains; in all cases tested, these species are shown to be embedded within the Cape clades. While many Cape clades show a relationship with the Eurasian temperate flora, this is complicated by their presence in tropical Africa. The single case study addressing this to date suggests that the Cape clade is nested within a European grade. Main conclusions Although many Cape clades show Austral rather than African relationships, there are numerous other patterns suggestive of a cosmopolitan flora. This spatial variation is echoed in the temporal data, from which, although there is wide variance around the dates of disjunctions, it is clear the Cape flora has been assembled over a long time period. There is no simple hypothesis that can account for the geographical sources of the currently distinctive Cape flora. The phylogenetic positions of Afromontane members of Cape clades suggest a history of dispersal from the CFR, rather than the reverse.     

Facing complexity in tropical conservation: how reduced impact logging and climatic extremes affect beta diversity in tropical amphibian assemblages

Biodiversity in pristine forest biomes is increasingly disturbed by human activity. Drivers such as logging and climate extremes are thought to collectively erode diversity, but their interactions are not well understood. However, ignoring such complexities may result in poor conservation management decisions. Here, we present the first study dealing with the complexity arising from the effects of interactions of two increasingly important disturbance factors (selective logging and climatic extreme events) on beta diversity patterns at different scales. Specifically, we examined extensive amphibian assemblage datasets obtained within a quasi‐experimental pre‐/post‐harvesting scheme in the lowland rainforests of Central Guyana. Changes in small‐scale patterns of beta diversity were not detectable at the higher landscape level, indicating that local‐scale dynamics are more informative for evaluating disturbance impacts. The results also underscore the importance of including abundance data when investigating homogenization or heterogenization effects, which should be considered when designing post‐logging impact assessments and selecting impact indicators. Moreover, logging should be regarded as a multifaceted driver that contributes to changes in biodiversity patterns in different ways, depending on interactions with other drivers. The effects of extreme climate events were significantly more pronounced in unlogged forest, while logged forest assemblages appeared buffered due to the presence of novel habitats. Imprudent post‐logging renaturation measures may thus counteract conservation targets. These findings highlight the fact that indicator bias and unaccounted interactions between multiple drivers can lead to misguided management strategies.     

Oligochaetes (Naididae,Tubificidae, Enchytraeidae and Alluroididae) of Guyana,Peru and Ecuador

More than 41 species in 23 genera of the microdrile oligochaete families Tubificidae, Naididae, Opistocystidae, and Enchytraeidae and the freshwater megadrile family Alluroididae have been identified in recent collections made in Peru, Guyana and Ecuador. Just less than 70% of our species records are new for one or more of these countries and one is a new, albeit tentative, generic record for the South American continent. About 16 species new to science remain to be described. One of these is only the second reported species of Brinkhurstia (Alluroididae) and possesses unusual, single, very elongate penial setae. All of our species records are pertinent to tests of different hypotheses about historical and phylogenetic relationships among organisms of northern and southern South America and North America. The species, including new ones, with limited distributions are of particular significance to such hypotheses.     

Oligochaetes (Naididae, Tubificidae, Opistocystidae, Enchytraeidae, Sparganophilidae and Alluroididae) of Guyana

About 50 species in more than 20 genera of the microdrile oligochaete families Tubificidae, Naididae, Opistocystidae, and Enchytraeidae and the freshwater megadrile families Sparganophilidae and Alluroididae were identified in recent collections made in Guyana. Only seven species in these families were previously recorded from Guyana. The aquatic oligochaete fauna has similar components to those of the southeastern United States, other locations in South America, and across lower latitudes in the northern hemisphere. A high diversity of species is found in the naidids especially in the genera Pristina and Pristinella, especially considering the small number of locations that have been sampled. The collections include approximately 12 new species of rhyacodrilines (Tubificidae), Dero, Pristina, Pristinella (Naididae), Brinkhurstia (Alluroididae), Hemienchytraeus and Aspidodrilus (Enchytraeidae). This is the first record of Aspidodrilus from outside of Africa and the first new record since 1952.     

A survey of the distribution and density of the primates of Guyana

In January through February 1994, we conducted the first broad-scale survey of Guyanese primates since 1975. Our goals were (1) to follow up questions raised in the earlier survey, (2) to compare population densities, and (3) to locate potential sites for future long-term research. We used distributional survey methods along trails and rivers and interviewed local inhabitants in each region. We surveyed five general areas, two of which had been studied in 1975. The distribution reported in 1975 for five monkey species—Alouatta seniculus, Cebus olivaceus, Pithecia pithecia, Chiropotes satanas,and Saimiri sciureus—was confirmed. However, questions were raised concerning the western extent of the range of three species: Ateles paniscus, Cebus apella,and Saguinus midas.In comparing densities between 1994 and 1975, we found a significant drop in group densities over the past 20 years and a shift in relative proportions of individual primate species over time. For example, although the total number of kilometers surveyed was identical, group densities were three times higher in 1975 than in 1994. Further, group densities of Ateles, Alouatta,and Pitheciawere much lower, while those of Saguinuswere similar in both years. These findings strongly suggest that habitat destruction and continued hunting pressure are affecting the primate populations.     

From the inside out: Discovery of a new genus of threadsnakes based on anatomical and molecular data,with discussion of the leptotyphlopid hemipenial morphology

The systematics of Leptotyphlopidae is historically controversial mostly due to their conserved external morphology in comparison with other snakes. However, recent studies have stressed that anatomical data might be informative for clarifying the leptotyphlopid taxonomy and evolution. We erect a new genus to accommodate Leptotyphlops collaris based on evidence from osteology, hemipenial morphology, and molecular data. We also provide expanded data regarding the intraspecific variation based on additional specimens collected in field trips and literature data, performing detailed comparisons among the new genus and all other New World leptotyphlopids. The new genus is distinguished from other leptotyphlopids by its unique hemipenial morphology and its exclusive combination of osteological and external morphology characters, with molecular data also supporting the new generic arrangement. We also provide a comprehensive discussion of the hemipenial morphology for the subfamily Epictinae based on literature and novel data gathered herein.     

Species diversity of bats (Mammalia: Chiroptera) in Iwokrama Forest, Guyana, and the Guianan subregion: implications for conservation

Fourteen species of bats are reported for the first time from Guyana (Saccopteryx gymnura, Micronycteris brachyotis, M. homezi, Lichonycteris obscura, Anoura latidens, Vampyressa pusilla, Vampyrodes caraccioli, Eptesicus chiriquinus, Cynomops paranus, Molossops neglectus, Molossus sp., Molossus coibensis, Molossus sinaloae, and Promops centralis) bringing the known bat diversity for the country to 121 species. Information including measurements, reproductive data, distribution, and taxonomy are provided for these species. Seven of these new records were collected in the Iwokrama International Rain Forest Programme site in central Guyana. Eighty-six bat species are now documented from Iwokrama Forest which is the highest species diversity for bats reported from any protected area in the world. There are, however, few tropical sites that have relatively complete inventories. A summary for bat species diversity in southern Venezuela, Guyana, Suriname, and French Guiana indicates that at least 146 species of bats are known from the Guianan subregion. Intense inventory surveys, especially in the often neglected subcanopy, suggest that species richness is probably underestimated in most Neotropical areas. Likewise, species-level diversity in the Guianan subregion is higher than previously suggested. Surveying and monitoring biodiversity are critical to developing a National Protected Areas System in Guyana.     

The shifting sources of racial definition in Trinidad and Tobago,and Guyana: a research agenda

This comparison of ethnic relations in two countries, Trinidad and Tobago, and Guyana, supplements the research findings of synchronic studies of "the social construction of race" by offering a historically based framework to understand particular and local instances of ethnic relations. Drawing on a long historical study of Trinidad and Tobago, and Guyana, I argue that the institutional sources of definition of key "ethnicities" have shifted through the centuries. "Ethnicities" have been successively defined by the institutions of capital, state and community. While these institutions have overlapped in time they are not equally important at a given moment in the matter of defining "ethnicity". The content of the definitions has also varied significantly. At present political communities and the family are the major social institutions that determine "ethnic" content.     

Birds as indicators of wetland status and change in the North Rupununi,Guyana

In financially and human capacity poor countries, there is an important need to monitor the status of resource rich ecosystems in the face of growing extractive activities in simple and inexpensive ways. In this study we explore the potential of using birds as indicators of ecosystem change in the wetland systems of the North Rupununi, Guyana, where local communities rely heavily on wetland resources for their subsistence activities. This is done by (1) assessing what environmental factors determine bird communities at different spatial and temporal scales; and (2) identifying indicator groups and/or species for ecosystem status. We surveyed 31 wetland sites over 2 years, taking monthly recordings of both the environmental features of waterbodies using a modified version of the River Habitat Survey and bird species counts. Using multivariate analyses, we found that large-scale habitat type, namely forest and savanna, and waterbody type, namely pond or main river channel, were the main factors affecting bird species distribution. At the smaller scale, habitat features around the waterbody and seasonality become important factors. We were able to identify lists of bird species associated with different waterbody types, and we present this as a checklist for future monitoring. We hope these findings can be integrated into the adaptive management and sustainable livelihood goals of the local stakeholders through linking monitoring with tourism and local school curriculum activities.     

Woody riparian plant distributions in western Oregon,USA: comparing landscape and local scale factors

We studied riparian forests along mountain streams in four large watersheds of western Oregon and far northern California, USA, to better understand the multiscale controls on woody riparian vegetation in a geographically complex region. In each of the four-study watersheds, we sampled woody riparian vegetation in161-ha sampling reaches that straddled the stream channel. Within each hectare, we sampled riparian vegetation and local environmental factors in 40 m² sampling plots arrayed along topographic transects. We also surveyed natural disturbance gaps in 6 ha in each watershed to explore the effects of fine scale disturbance on species distributions. We compared species composition across our study watersheds and used Nonmetric Multidimensional Scaling (NMS) and chi-squared analyses to compare the relative importance of landscape scale climate variables and local topographic and disturbance variables in explaining species distributions at sampling plot and hectare scales. We noted substantial turnover in the riparian flora across the region, with greatest numbers of unique species in watersheds at the ends of the regional gradient. In NMS ordinations at both scales, variation in woody riparian species composition showed strongest correlations with climatic variables and Rubus spectabilis cover, but the latter was only an important factor in the two northern watersheds. At the smaller scale, topographic variables were also important. Chi-squared analyses confirmed that more species showed landscape scale habitat preferences (watershed associations) than associations with topographic position (94.7% vs. 42.7% of species tested) or gap versus forest setting (94.7% vs. 24.6% of species tested). The woody riparian flora of western Oregon shows important biogeographic variation; species distributions showed strong associations with climatic variables, which were the primary correlates of compositional change between riparian sites at both scales analyzed. Additional local variation in composition was explained by measures of topography and disturbance.     

Manufacturing procedures and microbiological aspects ofParakari, a novel fermented beverage of the wapisiana amerindians of Guyana

The alcoholic beverageparakari, a unique fermentation product of cassava (Manihot esculenta Crantz) by the Wapisiana of Guyana, involves the use of a starch-hydrolyzing (amylolytic) mold (Rhizopus sp., Mucoraceae, Zygomycota) followed by a solid-state ethanol fermentation. A detailed study was made of theparakari manufacturing process in the Wapisiana village of Aishalton, South Rupununi, Guyana. Thirty steps were involved inparakari manufacture and these exhibited a high degree of sophistication, including the use of specific cassava varieties, control of culture temperature, and boosting of inoculum potential with purified starch additives. During the fermentation process, changes in glucose content, pH, taste, smell, and culture characteristics were reported for the fermenting mash.Parakari is the only known example of an indigenous New World fermentation that utilizes an amylolytic mold. Manufacture ofparakari is analogous to similar dual fermentations of the Orient, yet independently derived.