Resumen Introducción: Ephuta es un género de avispas mutílidas ampliamente distribuido en el Nuevo Mundo y cuya ecología es poco conocida. Objetivo: El objetivo de este trabajo fue determinar cómo varía la abundancia de especies de Ephuta anualmente y estacionalmente debido a las condiciones climáticas y sus hospederos. Métodos: Se examinaron especímenes de Ephuta tomados de muestras semanales (2001-2006) de diez trampas Malaise, ubicadas en el “bosque viejo” de Isla Barro Colorado. La abundancia mensual de cada especie de Ephuta se comparó con el promedio mensual de la humedad, la radiación solar, la temperatura y las precipitaciones. Resultados: Se identificaron nueve especies y diez morfoespecies. La mayoría de los especímenes fueron recolectados de marzo a junio. La mayor abundancia mensual promedio se dio en abril. De las cuatro variables abióticas medidas, solo la temperatura mensual promedio se correlacionó con la abundancia de Ephuta. Los meses con el mayor número de especímenes de Ephuta se correlacionan con la sospechosa abundancia del huésped, como lo indica la abundancia mensual de Pompilidae (Hymenoptera) capturada durante el 2007. Conclusiones: Ephuta muestra una fuerte variación estacional en la abundancia, con picos durante el final de la estación seca y el comienzo de la temporada de lluvias. Esta se correlaciona ampliamente con la temperatura y la abundancia de sus huéspedes pompílidos.

Abstract Introduction: Ephuta Say is a widespread New World genus of mutillid wasp whose ecology is poorly understood. Objective: The objective of this study was to determine how Ephuta species abundance varies annually and seasonally driven by weather conditions and hosts. Methods: Ephuta specimens, located in the “old forest” at Barro Colorado Island, were examined from weekly samples (2001-2006) of ten Malaise traps. The monthly abundance of each Ephuta species was compared with monthly average humidity, solar radiation, temperature and rainfall. Results: Nine species and ten morphospecies were identified. Most specimens were collected from March to June. April was the month reported with the greatest abundance. Of the four abiotic variables measured, only average monthly temperature was correlated with Ephuta abundance. Months with the highest number of Ephuta specimens were correlated with suspected host abundance, as indicated by the monthly abundance of Pompilidae (Hymenoptera) captured during the year 2007. Conclusions: We concluded that Ephuta display strong seasonal variation in abundance, with the peaks occurring during the end of the dry season and beginning of the rainy season, which correlate broadly with temperature and the abundance of their pompilid hosts.

Cololejeunea panamensis G. Dauphin & Pócs, descrita em 2006 foi referida como endêmica para a ilha de Barro Colorado no Panamá, América Central. Durante um estudo sobre a brioflora da ilha do Marajó, uma espécie de Cololejeunea mostrou-se diferente das espécies já registradas no Brasil, provando ser uma nova ocorrência para a América do Sul. O objetivo desse trabalho é divulgar a ocorrência dessa espécie em território brasileiro e ampliar o conhecimento sobre sua distribuição geográfica, morfologia e ecologia. O material estudado foi coletado na ilha do Marajó, município de Soure, estado do Pará, Brasil, no período de 10 a 16 de Janeiro de 2007. As amostras coletadas estão depositadas no Herbário do Museu Paraense Emílio Goeldi (MG). Foram coletadas um total de nove amostras contendo Cololejeunea panamensis, sendo esse o segundo registro já feito da espécie além do material tipo e o primeiro registro para a América do Sul. A espécie é descrita taxonomicamente, ilustrada e são feitos comentários sobre a distribuição geográfica, variação morfológica e habitat.

Cololejeunea panamensis G. Dauphin & Pócs was described in 2006 and cited as endemic to Barro Colorado Island in Panama, Central America. During a study on the bryophytes of Marajó Island, one of the Cololejeunea collected showed differences from the species recorded in Brazil, proving to be a new record for South America. The aim of this study is to report the occurrence of this species in Brazil and discuss its geographic distribution, morphology and ecology. The material studied was collected on Marajó Island, municipality of Soure, Para state, Brazil, from 10 to 16 January 2007. The collections are deposited in the herbarium of Museu Paraense Emílio Goeldi (MG). We sampled nine collections containing Cololejeunea panamensis. This is the second record for C. panamensis after the type collection and the first record in South America. The species is described taxonomically, illustrated and comments on geographic distribution, morphology and habitat are presented.

Comparamos características físicas de raíces aéreas de la palmera Socratea exorrhiza en sitios inclinados (pendiente>20º) y sitios planos, en dos lugares neotropicales. S. exorrhiza (n=80 árboles) no muestra diferencias en el número de raíces, la altura vertical de las raíces, la circunferencia y la masa del cono de las raíces, o la posición de las raíces en los sitios con pendiente. Encontramos relaciones positivas entre el crecimiento vertical y la arquitectura de las raíces aéreas, incluso entre el número de raíces, la circunferencia del cono de las raíces, y la masa del cono de las raíces. Es posible que las raíces aéreas permitan a S. exorrhiza crecer en altura y mantener la estabilidad mecánica sin involucrar el diámetro del tallo y la estructura de las raíces subterráneas. Probablemente, esta estrategia incrementa la capacidad de la especie para usar claros de luz rápidamente, en comparación con palmeras carentes de raíces aéreas; posiblemente también exista un incremento en su supervivencia cuando las adultas palmeras se acercan a sus límites de estabilidad mecánica.

Arboreal palms have developed a variety of structural root modifications and systems to adapt to the harsh abiotic conditions of tropical rain forests. Stilt roots have been proposed to serve a number of functions including the facilitation of rapid vertical growth to the canopy and enhanced mechanical stability. To examine whether stilt roots provide these functions, we compared stilt root characteristics of the neotropical palm tree Socratea exorrhiza on sloped (>20º) and flat locations at two lowland neotropical sites. S. exorrhiza (n=80 trees) did not demonstrate differences in number of roots, vertical stilt root height, root cone circumference, root cone volume, or location of roots as related to slope. However, we found positive relationships between allocation to vertical growth and stilt root architecture including root cone circumference, number of roots, and root cone volume. Accordingly, stilt roots may allow S. exorrhiza to increase height and maintain mechanical stability without having to concurrently invest in increased stem diameter and underground root structure. This strategy likely increases the species ability to rapidly exploit light gaps as compared to non-stilt root palms and may also enhance survival as mature trees approach the theoretical limits of their mechanical stability. Rev. Biol. Trop. 55 (3-4): 787-793. Epub 2007 December, 28.

Se estudió la distribución, mortalidad, reclutamiento y asociación con plantas, de 308 nidos de la hormiga neotropical Paraponera clavata en una parcela de cincuenta hectáreas de bosque viejo en la isla de Barro Colorado entre septiembre de 1993 y febrero de 1995. Los nidos estaban distribuidos uniformemente a través de toda la parcela, y se asociaban de manera significativa con el tipo de hábitat, existían más nidos de los esperados en las planicies altas y en la sección de bosque más joven de la parcela. La densidad promedio era de 6.2 nidos por hectárea. Los nidos con un mayor número de vecinos entre 0 y 20 m de distancia, tenían una mayor probabilidad de morir, si se comparaban con aquéllos que se encontraban separados por distancias mayores. La mortalidad era entre 13.36 y 69.64% dependiendo del intervalo de censo, y el reclutamiento fue del 22.63 y 31.72%. Los nidos se encontraron en las bases de 84 especies de plantas, en 34 familias con cuatro categorías de forma de vida: 76 especies eran árboles, 5 especies eran arbustos, 2 especies eran palmas y 1 era liana. Ocho especies de plantas se asociaban positivamente con los nidos de la hormiga. Plantas medianas entre 8 y 63.9 cm de DAP eran las más utilizadas. Arboles y arbustos pequeños presentan muy poca asociación con los nidos. La hormiga no se asocia con árboles que tienen nectarios extraflorales. El 53% de los nidos tenían a Phrynus gervaisii (Amblypygi: Phrynidae) habitando en el interior. Estos nidos presentaron menores tasas de mortalidad en comparación con el resto.

We studied the distribution, mortality and association with plants, of 308 nests of the neotropical ant Paraponera clavata, in a permanent 50 hectare plot in old-growth forest on Barro Colorado island between September 1993 and February 1995. Ant nests were uniformly dispersed throughout the plot, and significantly associated with the high plateau and patch of young forest in the plot. The average density was 6.2 nests per hectare. Mortality of nests was higher with increasing number of neighbors within 20 m, compared to those separated at greater distances. The mortality was between 13.36% and 69.64% depending on the census interval, and recruitment between 22.63% and 31.72%. The nests were found in 84 plant species of 34 families, pertaining to four life forms: 76 species were trees, 5 were shrubs, 2 were palms and one was a liana. We tested for association between ant nests and tree species and tree size by examining whether nests were more common in certain categories than would be expected by change. Eight species of plants were positively associated with Paraponera clavata. The ant preferentially selected trees between 8 and 63.9 cm diameter at breast height. Trees and small shrubs were not associated with the nests. No association was found between ant nests and trees with extra-floral nectaries. Fifty-three percent of the nests had a Phrynus gervaisii (Amblypygi: Phrynidae) cohabiting inside. These nests had lower mortality rates than the rest.