Bromeliads as biodiversity amplifiers and habitat segregation of spider communities in aNeotropical rainforest

The aim of this work is to characterize Nephilengys cruentata in relation to the diploid number, chromosome morphology, type of sex determination chromosome system, chromosomes bearing the Nucleolar Organizer Regions (NORs), C-banding pattern, and AT or GC repetitive sequences. The chromosome preparations were submitted to standard staining (Giemsa), NOR silver impregnation, C-banding technique, and base-specific fluorochrome staining. The analysis of the cells showed 2n = 24 and 2n = 26 chromosomes in the embryos, and 2n = 26 in the ovarian cells, being all the chromosomes acrocentric. The long arm of the pairs 1, 2 and 3 showed an extensive negative heteropycnotic area when the mitotic metaphases were stained with Giemsa. The sexual chromosomes did not show differential characteristics that allowed to distinguish them from the other chromosomes of the complement. Considering the diploid numbers found in N. cruentata and the prevalence of X 1 X 2 sex determination chromosome system in Tetragnathidae, N. cruentata seems to possess 2n = 24 = 22 + X 1 X 2 in the males, and 2n = 26 = 22 + X 1 X 1 X 2 X 2 in the females. The pairs 1, 2 and 3 showed NORs which are coincident with the negative heteropycnotic patterns. Using the C-banding technique, the pericentromeric region of the chromosomes revealed small quantity or even absence of constitutive heterochromatin, differing of the C-banding pattern described in other species of spiders. In N. cruentata the fluorochromes DAPI/ DA, DAPI/MM and CMA 3 /DA revealed that the constitutive heterochromatin is rich in AT bases and the NORs possess repetitive sequences of GC bases.Key words: chromosome, Araneae, heterochromatin, secondary constriction, Chromomycin A 3 . RESUMOAnálise citogenética da aranha neotropical Nephilengys cruentata (Araneomorphae, Tetragnathidae): coloração convencional, RONs, bandas C e fluorocromos base-específicos O objetivo deste trabalho é caracterizar Nephilengys cruentata em relação ao número diplóide, à morfologia cromossômica, ao tipo de sistema cromossômico de determinação sexual, aos cromossomos portadores de Regiões Organizadoras de Nucléolo (RONs), padrão de bandas C e seqüências AT ou GC repetitivas. As preparações cromossômicas foram submetidas à coloração convencional (Giemsa), à impregnação pelo nitrato de prata, técnica de obtenção de bandas C e à coloração com fluorocromos base-específicos. A análise das células mostrou 2n = 24 e 2n = 26 cromossomos nos embriões e 2n = 26 nas células ovarianas, sendo todos cromossomos acrocêntricos. O braço longo dos pares 1, 2 e 3 apresentou extensa região heteropicnótica negativa quando as metáfases mitóticas foram coradas com Giemsa. Os cromossomos sexuais Braz. J. Biol., 65(2): 193-202, 2005 194 ARAÚJO, D., CELLA, D. M. and BRESCOVIT, A. D.species possess the type X 1 X 2 X 3 X 4 /X 1 X 1 X 2 X 2 X 3 X 3 X 4 X 4 (Datta & Chatterjee, 1983), 5 species possess the type X 1 X 2 X 3 Y/X 1 X 1 X 2 X 2 X 3 X 3 (Maddison, 1982) and 2 species show the type X 1 X 2 Y/X 1 X 1 X 2 X 2 (Silva, 1988...

This study investigates how abundance, diversity and composition of understorey spiders were influenced by four different forest habitats in a southern Brazilian Araucaria forest. The study area encompasses a landscape mosaic comprised of Araucaria forest, Araucaria plantation, Pinus plantation, and Eucalyptus plantation. Understorey spiders were collected by beating the vegetation inside three patches of each forest habitat. To assess possible predictors of spider assemblage structure, several patch features were analysed: potential prey abundances, estimation of vegetation cover, diversity index of vegetation types, patch ages, patch areas, and geographical distance between patches.To assess the influence of high-level taxa approaches on spider assemblage patterns, analyses were carried out individually for family, genera and species levels. Additionally, Mantel tests were carried out in underlying similarity matrices between each taxon. Significant differences in spider abundances among forest habitats were found. Pinus plantations showed the highest abundance of spiders and Eucalyptus plantations showed the lowest abundance. Spider abundance was significantly influenced by patch ages, geographical distance and vegetation cover. Expected numbers of families, genera and species did not vary among forest habitats. Spider composition of two Eucalyptus patches differed from the other forest patches, probably due to their low vegetation cover and isolation. Genera composition was the best correlate of species composition, showing that a higher-level surrogate can be an alternative to the species approach.The understorey spider diversity in this managed area could be maintained when suitable habitat structures are provided, thus ensuring the connectivity between different habitat types. Further studies should focus on individual species responses to the conversion of native forest to monocultures.

The spider genus Ancylometes Bertkau, 1880 is revised. A. vulpes Bertkau, 1880, type species of the genus, is considered a junior subjective synonym of Dolomedes concolor Perty, 1833. Both types are lost and we redescribe the species based on specimens similar to those found at the type locality of A. vulpes. Spiders of the genus are large nocturnal ground-living hunting spiders with a strong affinity in most species, to water bodies within their tropical environment. Those species hunt also on small vertebrates like frogs, tadpoles and fishes. All species show slight sexual dimorphism in colour and body-to-leg-size relations. Females carry brown egg-sacs in chelicerae and build a nursery web. The genus is morphologically diagnosed by the presence of ventral spines on tarsi III and IV in both sexes and by their genital characters: filiform embolus with a basal membranous lobe, wing-like conductor and hammer-like median apophysis in males; female epigyne consisting of two broad lateral plates and a central plate in form of a bike saddle with its nose pointing posteriorly. Ten valid species are recognized and described, five of them are new: Ancylometes japura, A. jau, A. riparius from Amazonas, A. terrenus from Acre, Amazonas and Mato Grosso and A. pantanal from Matto Grosso do Sul, all from Brazil. The female of A. amazonicus is described for the first time and the female of A. hewitsoni for the first time based on an adult specimen. Ancylometes vulpes Bertkau, Ctenus argentinus Holmberg, Ancylometes bolivianus Tullgren, Lycoctenus bahiensis Strand, Lycoctenus selenkae Strand, Lycoctenus paraguayensis Strand, Cupiennius argentinus Petrunkevitch, Ctenus paulensis Mello-Leitão, Cupiennius diplocellatus Mello-Leitão, Ctenus originalis Mello-Leitão, Ctenus iophorus Mello-Leitão, Corinoctenus anomalostomus Mello-Leitão, Ctenus infelix (Mello-Leitão, Ctenus metatarsalis Mello-Leitão, Phoneutria niveobarbata Mello-Leitão and Corinoctenus greenwayi Carcavallo & Martinez are newly synonymized with A. concolor (Perty). Ctenus fuscus Walckenaer, Ctenus giganteus Taczanowski, Ctenus bimaculatus Taczanowski, Leptoctenus tenkatei Hasselt, Lycoctenus brunneus Pickard-Cambridge, Lycoctenus gigas Pickard-Cambridge, Lycoctenus demerarensis Pickard-Cambridge, Lycoctenus saraensis Strand, Lycoctenus paraensis Strand, Ancylometes pindareensis Mello-Leitão, Ancylometes pindareannus Mello-Leitão, Ctenus juruensis Mello-Leitão, Ctenus striolatus Mello-Leitão, Ctenus xerophilus Mello-Leitão and Lycoctenus titanus Caporiacco are newly synonymized with A. rufus (Walckenaer). Lycoctenus palustris Pickard-Cambridge, Ancylometes orinocensis Simon, Lycoctenus venezuelensis Strand, Lycoctenus caracasensis Strand and Ctenus nasutus Kraus are newly synonymized with A. bogotensis (Keyserling). A. valentinei Petrunkevitch, 1925 from Panama is a Cupiennius (new combination) and considered a senior synonym of C. panamensis Lachmuth et al., 1985. The geographical distribution is Neotropical, with one northern widespread species (A. bogotensis) reaching Central America, one widespread species of the Amazon reaching the São Paulo coastal area and one widespread species of central Brazil reaching Argentina. From the Amazon region six rarely collected species are described and one species was recently collected in the Pantanal of Brazil.

Microhabitat selection and co-occurrence of Pachistopelma rufonigrum Pocock (Theraphosidae) and Nothroctenus fuxico sp. nov. (Ctenidae), in tank bromeliads were investigated. Thermal conditions, inside and outside the plants, were measured in order to verify if the temperature of the water that accumulates inside the plant affects the behavior of these species. Measurements of foliar parameters were taken in order to evaluate if and how plant structure affects spider abundance and microhabitat selection. Apparently, differences in plant structure do not affect either spider abundance or microhabitat selection. No microhabitat preference was observed and co-ocurrence of both species was a random event. In addition, notes on the distribution range of P. rufonigrum and the description of N. fuxico sp. nov. from State of Sergipe, Brazil are presented.
Foram estudadas a seleção de microhabitat e co-ocorrência de Pachistopelma rufonigrum Pocock (Theraphosidae) e Nothroctenus fuxico sp. nov. (Ctenidae) em bromélias-tanque. A condição da temperatura dentro e fora das plantas foi medida para verificar se a temperatura da água acumulada dentro da bromélia afeta algum aspecto comportamental das aranhas que ali vivem. Medidas dos parâmetros foliares foram realizadas para avaliar se a estrutura das plantas chega a afetar a abundância ou a seleção de microhabitat dessas aranhas. Aparentemente, as diferenças na estrutura das duas espécies de bromélias estudadas não afetam nem a abundância, nem a seleção de microhabitat de P. rufonigrum e N. fuxico sp. nov. A preferência e co-ocorrência de ambas as espécies de aranhas parece ser um evento ao acaso. Adicionalmente, apresenta-se notas sobre os limites de distribuição de P. rufonigrum e descreve-se N. fuxico sp. nov. do Estado de Sergipe, Brasil