Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Se presenta la descripción e ilustración de Pleuridium tucumanensis, una nueva especie de Pleuridium, sección Pleuridium, en Argentina. P. tucumanensis presenta las hojas extendido incurvadas, una característica rara en el género. Se compara con las especies relacionadas destacando sus diferencias morfológicas.

The study was carried out in a median stature tropical forest in the north of Quintana Roo during 2008, 2010-2012, using camera traps to record activity and habitat use by jaguar and other vertebrates. Spatial and temporal variations in habitat use, activity patterns, and species associations were analyzed using a chi-squared test (x2). Generalizedlinear models (GLM) were used to determine which variables influenced the presence of jaguars in the study area. Jaguars were most frequently recorded in acahual (80%) and on roads (66.9%). There were significant differences between years, with selection for particular habitat and trail types in 2008 and 2011 (all χ2 p <0.001). Jaguars were mainly crepuscular-nocturnal (68.5% records). They showed spatial associations with Meleagris ocellata, Dasypus novemncinctus, Mazama temama, Nasua narica, Odocoileus virginianus, Leopardus pardalis, Didelphis spp., andPecari tajacu. Generalized linear models based on prey, co-predators, and human activity gave the best fit with jaguar occurrence. The felids responded to environmental changes (hurricanes and fires) by modifying their spatial and temporal use of resources.

The objective of this work is to know the structure (composition and density) of the community of the oribatid mites and their relationship to edaphic parameters in 2 agricultural parcels with different type of irrigation. It constitutes the first work done with oribatid mites in agricultural plots irrigated with waste water in Mexico. Two agriculturalparcels were selected: one is irrigated with waste water (San Salvador) and the other with well water (El Bondho) from the municipality of San Salvador. The density of oribatids in San Salvador was higher than that from El Bondho (2,360 and 1,935 ind/m2, respectively). The maximum abundances in percentages in San Salvador were for 3 species: Tectocepheus velatus elegans (48%), Scheloribates sp. (15%) and Oppiella nova (13%); but for El Bondho, there were only 2 species: Zygoribatula connexa (74%) and Ramusella sp. (10%). Due to soil conditions by the irrigation type, results gave information, on one hand, about the tolerance of some species like O. nova, R. ardua, and T. velatus elegans to heavy metals, and on the other hand, about the low resistance to heavy metals of Epilohmannia pallida and Z. connexa, which were present in the less polluted parcel, but are tolerant to saline soils. Results can be useful to support the use of some species of oribatid mites as bioindicators in ecosystems with similar conditions.

The Scombridae fishes are of great commercial importance in Brazil, but infections caused by helminth parasites can reduce its commercial value. Thunnus obesus from the coastal zone of Rio de Janeiro was examined for helminth parasites. Three species of Didymozoidae were found: Didymocystis alalongae Yamaguti, 1938 in gill raker and operculum, Didymocystis lamotheargumedoi Kohn & Justo, 2008 associated with 3 immature forms in the operculum and Platocystis vivipara (Yamaguti, 1970) Pozdnyakov, 1987 in the skin of dorsal region. T. obesus represent new host record for Didymocystis alalongue and for D. lamotheargumedoi and Platocystis vivipara is reported for the first time in the Southwest Atlantic Ocean.

Ecological niche models have seen intensive exploration as a tool in biodiversity conservation and evaluation of areas for designing protected natural areas systems, including projections of potential distributions under future conditions. Cloud forest is the most endangered ecosystem in Mexico, and yet ranks high in terms of diversity and endemism. This study focuses on 12 endangered and range-restricted tree species in Mexican cloud forests, exploring patterns of distribution and diversity under 2 future emissions scenarios (representative concentration pathways 4.5 and 8.5) as anticipated by 20 general circulation models. Our results indicate a likely strong reduction in species’ distributional areas and —consequently— species diversity manifested in different cloud forest patches across the country. The genus Quercus resulted the most sensitive to climate change. We identified cloud forest patches that are most vulnerable to climate change effects, which can and should focus priorities for protection of this ecosystem, particularly in the Sierra Madre Oriental, where cloud forest is presently lacking any protection.

En orquídeas, la forma y tamaño de caracteres florales como el labelo, sirve para clasificar variación dentro y entre especies. El objetivo del presente trabajo fue caracterizar la variación morfológica infraespecífica a través del labelo de Vanilla pompona analizando 80 flores provenientes de 23 ejemplares del estado de Oaxaca, México. El labelo de cada flor se diseccionó y analizó mediante su morfometría geométrica, obteniéndose 60 variables que se agruparon en región basal, media y apical. Se realizó un análisis de varianza que consideró las recolectas como fuentes de variación y 2 análisis multivariados, componentes principales y conglomerados. Entre recolectas, 58 variables analizadas fueron estadísticamente significativas. El modelo explicó 81% de la variación total estudiada con los 3 primeros componentes principales. Existe variación morfológica floral del labelo en Vanilla pompona representado por 4 morfotipos en Oaxaca, resultado de la probable presión y selección por parte de los polinizadores y el ambiente, donde los complejosmontañosos posiblemente han coadyuvado como barrera geográfica.

Although Mexican Cactaceae are a significative component of Mexican flora and have a relevant economic and ornamental value, the knowledge of the environmental factors characterizing their niche is still rather limited. This study was aimed at defining the ecological niche and potential distribution of 9 species of the genus Thelocactus. Climatic and topographic variables constraining the distribution of Thelocactus species were identified by means of environmental niche models (ENM) and ordination techniques and used to generate potential distribution maps. The constructed ENMs were compared to assess the similarities of the ecological niche of Thelocactus species and to know if they share the same ecological niche space. The distribution of Thelocactus species was mostly limited by isothermality and precipitation of wettest quarter. The differences in habitat requirements were well documented by the significative differences in the niche ecological space as shown by the equivalency test, while the high percentage of niches that were more similar than expected by chance suggest a high degree of niche conservatism among Thelocactus species. The spatial predictions could serve to improve field design sampling to discover new populations, while niche characteristics could be relevant for improving preservation actions and guiding reintroduction programs for a better conservation of Thelocactus species.

Salvia hispanica L. is an annual herbaceous plant, belonging to the Lamiaceae family, it stands out as the natural resource of plant origin with the highest content of fatty acids known so far. To obtain success in the production of seeds it is necessary to use lots of high quality, which can be evaluated, through the vigor of the same, at present, one of the main requirements for the evaluation of vigor refers to the obtaining of reliable results in a relatively short period of time. The tetrazolium test stands out for being fast and reliable. However, the methodology for the genus Salvia is not referenced within the standards of the International Seed Testing Association (ISTA), considering these facts, it becomes important to carry out the experiment for the development of a protocol that allows this analysis. The research was carried out in the Seed Laboratory of the Federal University of Pelotas, six batches of black chia seeds were used and four concentrations of tetrazolium salt (0.075%, 0.1%, 0.5% and 1%) were tested to evaluate the seed viability. The experimental delineation was in randomized blocks, submitted to the analysis of variance through the F test and subsequently the means compared to each other by the Tukey test, at 5% probability, for comparison of the means. The tetrazolium test conducted in the concentration of 0.075% is efficient to evaluate the viability of the seeds of S. hispanica L., as well as to differentiate lots with different physiological quality.

In order to investigate the effect of rootstock patterns and cultivation techniques on the yield and quality of watermelon fruit, a study was conducted between October 2014 and February 2015 in the municipality of Santa Elena, Ecuador. The watermelon hybrid Royal Charleston grafted on three patterns (Shintoza, RS-841, Ercole interspecific hybrids of Cucurbita maxima x Cucurbita moschata), three planting densities (3 000, 3 500, 4 000 plants ha-1), pruning were evaluated (without pruning, three and four main guidelines) and three doses of gibberellic acid (0, 10, 20 mg L-1), applied in the transplant and 20 and 40 days after it, in an orthogonal design L9 (3)4 arranged in random blocks with three replicas. The variables evaluated were stem diameter, fruits per plant, fruit mass, agricultural yield (t ha-1), total soluble solids, pulp firmness and bark thickness. In addition, the ‘regular analysis’ was carried out, which includes the preparation of the response table, selection of the optimal combination and the prediction of the maximum response. The Royal Charleston watermelon hybrid grafted onto the RS-841 pumpkin pattern, using the approximation method, with a density of 4 000 plants ha-1, four main guides and the application of 20 mg L-1 gibberellic acid respectively, reached the greater amount of fruits per plant and therefore higher yield, result that was confirmed by the regular analysis performed.

With the objective of contributing to the knowledge of the results of the rural extension public policy in Mexico, the degree of adoption of new technologies and capacity development among the beneficiaries was analyzed according to different attributes and characteristics of their production units. The 2014 national survey of beneficiaries of the monitoring and evaluation system of the extension and productive innovation component was used, which collected information in ten states of the republic and its sample size amounted to 1 062 questionnaires. The rate of adoption of new technologies and capacity development was calculated and it was found that -in contrast to the modernizing paradigm on which the national extension policy is based- small producers are not the priority population for a results-oriented policy, but rather those with average income and productive assets. Statistically significant differences were found between the average value of the index and variables such as sex, age, schooling, area and investment in assets of the production unit, this allows to establish specific strategies to promote a public policy of differentiated extension, focused on empirical evidence to production unit level.