Venezuelan Guayana Research Articles

The recovery of logged forests proves that a viable management is possible in the Venezuelan Guayana Shield

Aim of study: To compare the diversity and biomass of logged forests, with different ages after harvesting and the risk of their degradation to liana forests.
 Area of study: We studied 18 plots at the central zone of the Imataca Forest Reserve (Guayana shield), Venezuela.
 Material and methods: We used 1-ha plots, to measure individuals with dbh > 10 cm in control plots (0 years) and in logged plots with 3, 9, 12, 15 and 18 years after logging. The main variables evaluated were enlarge importance index (EII), richness (R), Shannon-Weaner index (H´), Alpha Fischer (α), basal area for commercial species (BA_comm), above-ground carbon (C) and lianas abundance at the understory (Lianas_%Au).
 Main results: Diversity variables (R: 62-77 spp ha-1, p: 0.117-0.838; H´: 2.8-3.4, p: 0.181-0.677; α: 18.6-25.4, p: 0.293-0.922) and biomass (89.6-180.2 MgC ha-1, p: 0.171-0.895) did not have significant differences between control and most of the logged plots. Only the 18 years-old forests had statistically higher values of diversity (R: 81-94 spp ha-1, p: 0.000; H´: 3.8-3.9, p: 0.000; α: 26.8-31.7, p: 0.000), perhaps due to a high impact skidding operation. Commercial species were not recovering after logging.
 Research highlights: Forest management can be viable in this area, but it requires reduced impact logging techniques and better silvicultural systems to guarantee future harvest of high value commercial timber.

Freshwater crabs from the highlands of the Venezuelan Guayana

Freshwater crabs from the highlands of the Venezuelan Guayana

New or Little-Known Epiphyllous Liverworts, XXIV. A Collection Made in the Venezuelan Guayana at the Foot of Salto Angel with Description of Cololejeunea Bencei

A liverwort collection by Bence Pócs from the Venezuelan Guayana resulted in 31 species of liverworts, including Cololejeunea bencei new to science and C. cardiocarpa, C. obliqua, C. platyneura, C. schusteri, C. verwimpii, Lejeunea pulchra and Plagiochila crispabilis new to Venezuela. The distribution and differentiation of C. schusteri is discussed.

Rural regional planning in the Venezuelan Guayana: an approach to inform decision-making in peripheral areas

ABSTRACT The Venezuelan economic crisis, combined with the creation of the Orinoco Mining Arc (OMA), has pushed thousands of people to work in wildcat mines in the Venezuelan Guayana. Even though attempts have been made to control illegal mining in the past, the absence of planning and lack of concrete economic alternatives have made these efforts unsuccessful. Spatial planning could play an important role in developing a rural regional strategy aimed at making other livelihood options available. This is a challenging endeavour, however, because the Venezuelan Guayana is the largest and least populated region of the country, with most of its surface covered by fragile forests rich in ecological and cultural diversity. Moreover, data to inform decision-making are unavailable or severely limited. This paper presents an approach that attempts to overcome those obstacles and seeks to identify which are the peripheral remote areas where resource extraction and its negative externalities are most present, conflicting with the preservation of the forest, its biodiversity and the livelihoods of Indigenous populations. The conclusions presented here might assist spatial planners and policymakers who seek to explore territorial approaches for rural development and inform decision-making in peripheral regions where data are scarce.

Tovomita nebulosa (Clusiaceae), a new species from Cerro de la Neblina, Venezuela

ABSTRACT Although the number of recently described Tovomita species is relatively high, much more remains to be done, given that each new survey of representative Amazonian collections reveals many potentially undescribed taxa. In the treatment for Tovomita published in Flora of the Venezuelan Guayana, at least six distinct morphotypes did not match any previously described species. Here we recognize morphotype “D” as a new endemic species from Cerro de la Neblina. Additionally, we provide an identification key to the Tovomita species in Venezuela.

Taxonomic novelties in Clusia (Clusiaceae) from Venezuela

Although a comprehensive taxonomic treatment of the genus Clusia in the Venezuelan Guayana was published 20 years ago, much taxonomic work remains to be done regarding the genus in the region, including description of new species. In this paper we describe and illustrate five new species of Clusia sect. Oedematopus (Clusia dickinsoniana, C. donramonii, C. peterstevensii, C. punctata and C. tetramera), which are characterized by their small flowers without resin or nectar secretion.

Notes on the Burseraceae in central Amazonia, including four new taxa. Studies in neotropical Burseraceae XXVI

The Burseraceae are known to comprise one of the most important tree families in Amazonia, but examination of Burseraceae diversity indicates that this importance is achieved differently in different parts of the Amazon, generally showing greater relative density compared to relative diversity in the east and greater relative diversity compared to relative density in the west, but both high relative density and diversity in central Amazonia. The patterns of relative density may be explained by current climates and by soils, but those of diversity are more likely a function of historical events. Revision of the Burseraceae for two projects near Manaus, Brazil revealed four new taxa. Protium hebetatum is widespread in western Amazonia, but it is one of the most common trees in central and west-central Amazonia; it resembles P. grandifolium. Protium tonyanum is a distinctive new species in poorly resolved sect. Sarcoprotium. Protium paniculatum var. modestum is known thus far only from the vicinity of Manaus plus several localities in the state of Amazonas, Venezuela; a key to the varieties is provided. Dacryodes hopkinsii is one of a group of four species in that genus from Amazonia and the Venezuelan Guayana with relatively large and fleshy flowers that are functionally bisexual. The discovery of these new taxa underscores the biological importance of Manaus and vicinity as a center of diversity for many taxa and exemplifies the synergy between well-designed floristic projects and systematics.

Five New Species of Caraipa (Calophyllaceae) from the Venezuelan Guayana

Abstract Five new species of Caraipa endemic to the Venezuelan Guayana are here described and illustrated. Three species are endemic to the Amazonas state: Caraipa acutata, endemic to the Guainia river; Caraipa cordifolia, endemic to the Paru tepui; and Caraipa yutajensis, endemic to the Yutaje tepui. Two species are endemic to Bolivar state: Caraipa kubitzkii was collected on a river margin in uplands; and Caraipa nigrolineata from the uplands. We propose two synonymizations and present an identification key for the 20 species of Caraipa from Venezuela.

La circunscripsión de Palicourea subgen. Heteropsychotria (Rubiaceae Palicoureeae)

The subgenus Heteropsychotria was detected and described by Julian Steyermark in the frame of the monographic series of the Botany of the Guyana Highland (Steyermark 1972) and repeatedly in a more illustrated version in the Flora of Venezuela (Steyermark 1974). Within the subgenus he distinguished 13 sections and 31 series. Three sections (Nrs 4, 7 and 11) of the 13 remained without names and descriptions. After the fundamental molecular taxonomic study of Nepokroeff et al. (1999) a publishing activity started producing a number of critical studies separating some sections as valid individual genera. The section Chytropsia has been included into the genus Margaritopsis Ch. Wright (Andersson 2001, Taylor 2005). The section Notopleura regained its generic status according to Bremekamp’s original concept (Taylor 2001). The Mapouria section has been eliminated by the re-establishment of the Carapichea genus (Andersson 2002b, Taylor and Gereau 2013). It has been recently recognised, that the greater part of th...

Novelties in the Orchid Flora of Venezuela IX. Subtribe Pleurothallidinae. New Combinations inAnathallisand a New Report for the Orchid Flora of Colombia

We discuss a group of four species from the Venezuelan Guayana, two of them closely related to Anathallis nanifolia (based on Pleurothallis nanifolia). These two species, Pleurothallis deborana and P. pemonum, were erroneously placed in the synonymy of Anathallis holstii (based on Pleurothallis holstii). We propose new combinations in Anathallis for these two species, discuss the current status of all four species, and provide a key to distinguish them.

Manipulus Guttiferarum, I. Caraipa pilosa (Calophyllaceae), a new species from the Parú massif, Venezuelan Guayana

In this paper we describe and illustrate Caraipa pilosa, a new species from the Venezuelan Guayana endemic to the Parú massif, morphologically similar to C. aracaensis, a species endemic to Serra do Aracá in Amazonas, Brazil. These two species have similar leaf type (conspicuously coriaceous, the margins revolute and with conspicuous pubescence on the abaxial leaf surface), but in Caraipa pilosa the trichomes are longer (≤1 mm) than in C. aracaensis (≤0.1 mm) and present in young stems, upper leaf surface (especially in young leaves), inflorescence axes, sepals, ovaries, and fruits. Also, in Carapia pilosa, leaf blades are consistently larger than in C. aracaensis. Caraipa pilosa is only known from the montane forest of Cerro Parú, and its conservation status is Least Concern (LC, following the IUCN Red List categories).

<p><strong>Manipulus Guttiferarum, I.<em> Caraipa pilosa </em>(Calophyllaceae), a new species from the Parú massif, Venezuelan Guayana</strong></p>

In this paper we describe and illustrate Caraipa pilosa, a new species from the Venezuelan Guayana endemic to the Parú massif, morphologically similar to C. aracaensis, a species endemic to Serra do Aracá in Amazonas, Brazil. These two species have similar leaf type (conspicuously coriaceous, the margins revolute and with conspicuous pubescence on the abaxial leaf surface), but in Caraipa pilosa the trichomes are longer (≤1 mm) than in C. aracaensis (≤0.1 mm) and present in young stems, upper leaf surface (especially in young leaves), inflorescence axes, sepals, ovaries, and fruits. Also, in Carapia pilosa, leaf blades are consistently larger than in C. aracaensis. Caraipa pilosa is only known from the montane forest of Cerro Parú, and its conservation status is Least Concern (LC, following the IUCN Red List categories).

Late-Holocene gallery forest retrogression in the Venezuelan Guayana: New data and implications for the conservation of a cultural landscape

Fire is considered a major threat to forest conservation in the Neotropics. Palaeoecological studies are critical for understanding the long-term interactions of climate, fire, and human activities in the savanna–forest dynamic. Here, new data from palynological analyses conducted in sedimentary records from the northern edge of the Amazon Basin, the Gran Sabana, southeast of Canaima National Park (CNP) are presented. Four radiocarbon ages from Quebrada Kowana (QK) and two for Ariwe Fernland (AF) records showed that both are late-Holocene age (with extrapolated basal ages of 3100 and 3400 cal. yr BP, respectively). Both showed the occurrence of gallery forest until 1800 (QK) and 1600 (AF) cal. yr BP, with forest taxa reaching 60% and 40% of the terrestrial pollen sum, respectively. The main forest taxa were Celastraceae, Moraceae/Urticaceae, Schefflera, Protium, and Mahurea (QK) and Dimorphandra, Protium, Schefflera, Tachigali, and Blepharandra (AF). Savanna herbs (mainly Poaceae) reached 40–50% (QK) and 60% (AF). The high abundance of savanna herbs together with the low occurrence of mature forest taxa, and high abundance of pioneer taxa, suggests that the former forests comprised very open and disturbed forest-belts, surrounded by savannas. Since 1800 (QK) and 1600 (AF) cal. yr BP, forest taxa dropped to 10% and 5%, respectively, suggesting the substitution of forests by herbaceous communities. The high abundance of charcoal recorded from the beginning of the records to about 1800–1600 cal. yr BP suggests that recurrent fires spreading from neighboring savannas were reaching the former forest, causing compositional changes and triggering forest reduction. Fires were very likely human-made, but highly controlled by climate. Hence, forest substitution happened when a combination of local fires and droughts was given in every record. Results agree with those from other localities in the CNP in confirming the occurrence of regional-scale gallery forest degradation during the late Holocene.

Hydrolutos piaroa sp.n. (Orthoptera: Anostostomatidae), a new semiaquatic Lutosini species from south-western Venezuelan lowland streams.

Hydrolutos piaroa, anew species of Lutosini (Orthoptera: Anostostomatidae) from Tobogán de la Selva (Puerto Ayacucho region, SW Venezuela) is described and figured. Inhabiting aquatic environment it represents an unusual orthopteran with sternal and pleural area covered by fine microtrichia, forming a plastron. This is the first known Hydrolutos species sampled in lowland streams of Venezuelan Guayana.

Novelties in the Orchid Flora of Venezuela VIII. Subtribe Eriopsidinae.Eriopsis.1

We present a revision of all the species and available names of Eriopsis, a long misinterpreted genus of Orchidaceae described by John Lindley in 1847. A new species from the Venezuelan Guayana, E. escalerensis, is described and illustrated. An additional species from the Andes is circumscribed morphologically and geographically, but it remains undescribed until further data are available. A key to identify all the seven recognized species, conservation assessments in accordance with the B set of criteria of the IUCN, and miscellaneous notes are also provided.

A New Species ofFreziera(Pentaphylacaceae) from the Venezuelan Andes

Freziera Willd. is a Neotropical genus of functionally dioecious trees or shrubs with alternate leaves and lenticellate, often pubescent twigs sometimes organized in a zig-zag fashion. The genus is distributed from Mexico to Bolivia, including the Guayana Highlands, and the West Indies (Weitzman, 1987). Species of Freziera mainly occur in cloud forest (1000–3200 m) and sometimes in paramos, although some species may have a wider altitudinal range, from near sea level to middle elevation forests at about 1,800 m (Weitzman, 1987). Nine species are known to date from Venezuela. Four species are present in montane forests in the Andes of Merida to the Cordillera de la Costa (F. candicans Tul., F. chrysophylla Bonpl., F. grisebachii Krug & Urb., and F. tomentosa (Ruiz & Pav.) Tul.); three species are found in montane forests of the Venezuelan Guayana (F. calophylla Triana & Planch., in Amazonas and F. carinata A. L. Weitzman and F. roraimensis Tul., in Bolivar and Amazonas); and two species are known only from the Andes (F. bonplandiana Tul. in Tachira and F. karsteniana (Szyszyl.) Kobuski in Merida) (Berry and Weitzman, 2005, 2008). Berry and Weitzman (2008) suggest there may be a third species of Freziera in forest areas on slopes of RoraimaTepui in the Venezuelan Guayana (F. roraimensis Tul.) which has been also cited by Berry & Weitzman (2007); however its presence there has still not been confirmed and the species is known only from the type collection, which does not mention a specific locality. There is an additional Venezuelan species of Freziera, which is apparently very common in forests and paramos of the Andes in Merida, Lara and Trujillo. Weitzman (1987) originally identified it as a new species, F. serrata A. L. Weitzman ined. It has since been cited by that name in different floristic and vegetation studies in Venezuela (Dorr

Riqueza y Distribución Altitudinal de Gramíneas C3 y C4 en la Guayana Venezolana

<p>Se estudiaron la riqueza de especies y el patrón de distribución altitudinal de las gramíneas C3 y C4 en la<br />Guayana venezolana. Las gramíneas están representadas en el gradiente altitudinal por 411 especies, de las cuales, 170 presentan la vía fotosintética C3, y 241, la C4. Las gramíneas C3 y C4 están más diversificadas en las tierras bajas, no obstante, las C3 exhiben un patrón particular; así, en las tierras bajas se distribuyen ecológicamente en hábitats sombreados (sotobosques). En las tierras altas, las especies C3 desplazan a las C4, que están mínimamente representadas. El patrón de distribución altitudinal de las gramíneas C3 y C4 sigue la regla de Rapoport.<br /><strong></strong></p><p><strong>Palabras clave:</strong> Diversidad en gradientes altitudinales, Gramíneas C3 y C4, Flora de la Guayana, Gramíneas neotropicales, Regla de Rapoport.</p>

Ephemeroptera from the Venezuelan Guayanas's Uplands: Families Leptophlebiidae, Euthyplociidae and Oligoneuriidae.

As a continuation of a series of papers to improve the knowledge of the Ephemeroptera fauna of the Venezuelan Guayana's Uplands, an update of the families Leptophlebiidae, Euthyplociidae and Oligoneuriidae in the region is presented. As a result, Paramaka incognita sp. nov. is described, the female of Askola emmerichi is described for the first time, and the genera Askola, Hydrosmilodon and Leentvaaria, the subgenus Miroculis (Atroari) and the species Miroculis (M.) marauiae are recorded for the first time for Venezuela.

A new species and a new combination in Phaeostemma (Apocynaceae, Asclepiadoideae, Gonolobinae)

Phaeostemma surinamensis Morillo & Krings, sp. nov., anew species of Apocynaceae (Asclepiadoideae, Gonolobinae) is described and illustrated, and the new combination Phaeostemma fucata (Woodson) Morillo & Krings, comb. nov., is made. The new species, known only from a lowland wet forest of Suriname, seems to be closely related to Phaeostemma fucata, which is an endemic to Ptari-tepui, a sandstone mountain in the southeastern edge of the Venezuelan Guayana.

Chemical Composition of the Essential Oil from the Leaves of Carapa guianensis Collected from Venezuelan Guayana and the Antimicrobial Activity of the Oil and Crude Extracts

The essential oil obtained by hydrodistillation of Carapa guianensis Aubl. (Meliaceae) leaves was analyzed by GC-FID and GC-MS. Twenty-three components were identified, which made up 93.7% of the oil. The most abundant constituents were bicyclogermacrene (28.5%), alpha-humulene (17.2%), germacrene B (11.9%), and trans-beta-caryophyllene (9.9%). Antimicrobial activity of the essential oil, as well as the crude extracts of the leaves obtained by refluxing the dried leaves with n-hexane, dichloromethane, and methanol, was determined using the disc diffusion assay. Activity against Staphylococcus aureus ATCC 29923 and Enterococcus faecalis ATCC 29212 was only found for the essential oil and the methanolic extract, at minimal inhibitory concentrations (MIC) of 400 microg/mL and 50 microg/mL.