Everton Nei Lopes Rodrigues

Effect of the insecticide Lambda-cyhalothrin on rice spider populations in southern Brazil

The adverse effect that insecticides have on spider populations is of major concern since these predators are a component in the biological control of rice insect pest populations. This study was designed to determine the effect of the pyrethroid insecticide, Lambda-cyhalothrin, on spider populations in rice fields. Treatments consisted of plots treated once with the insecticide and untreated plots (control). Spiders were sampled four times per crop year over a two year period in each of three sites in the state of Rio Grande dol Sul, Brazil. Treatments were replicated four times. Sweep net sampling was conducted to sample the araneofauna. Overall 1,961 spiders were collected, with a predominance of juveniles over adults. Between treatments, there were significantly larger numbers of spiders and species richness in areas without insecticide. There were also significant differences among areas (sites) and among days after the insecticide application. Of the 12 recorded families, Araneidae and Tetragnathidae dominated, and were both strongly affected by insecticide application, decreasing more than 50% in those locations. Overall, 37 species were recorded (insecticide: 29; without: 26), eleven species were exclusive for rice without insecticide and eight for rice with insecticide. Alpaida veniliae (Keyserling, 1865) (n = 236) and Tetragnathaaff.jaculator (108) were the most abundant in both treatments, but with large decreases in abundance in rice with insecticide. Among guilds, the predominance was for orb weavers (67.3%) in all locations, but with much lower values for those spiders in rice with insecticide application. This study illustrates that the spider fauna in rice fields are adversely affected by the application of the insecticide Lambda-cyhalothrin.

Habitat structure determines spider diversity in highland ponds

Wetlands (e.g. ponds, meadows) can be found in many landscapes, playing an important role in maintaining regional biodiversity and supporting heterogeneous communities. Spiders are diversified predators that are highly influenced by changes in plant community structure, heterogeneous habitats sustain high spider diversity and abundance. We investigated the characteristics of spider biodiversity in ponds with different habitat structures, by examining patterns across habitats of ponds with different vegetation levels. Sampling took place in four occasions over a year. We compared spider abundance, species richness and composition among ponds including distinct vegetation variables, related to life form, type of leaves, coverage and height. Overall 1174 individuals (194 adults) of 11 families and 37 morphospecies were sampled. We found mostly expected differences in the manner that communities were structured between different habitats. Thus, higher variability of abundance was explained for higher habitat structure of ponds. We also found differences in species composition between ponds with low emergent vegetation and higher habitat structures. Additionaly, spiders were consistently structured more by turnover than nestedness components, with a greater beta diversity of web-builders. Our results suggest varying levels of habitat structures and species substitution shape pond spider communities, depending on habitat heterogeneity and spider guild. Those findings demonstrate the clear role of spatial habitat structure, with more spider species preferring to build webs or actively hunt at vegetated environments on ponds.

On the spider genus Neonella (Araneae: Salticidae): new records and taxonomic notes for species from southern South America

The genus Neonella Gertsch, 1936 contains 12 species with an exclusive New World distribution (World Spider Catalog 2015). The genus was proposed by Gertsch (1936) to include N. vinnula Gertsch, 1936 from Florida and Texas, USA. Remaining species were added by Galiano (1965, 1988, 1998) and, more recently, Edwards (2003), Ruiz & Brescovit (2004), and Ruiz et al. (2007).

New species and records of cunaxid mites (Acari: Cunaxidae) from soil in Southern Brazil

Neocunaxoides promatae sp. nov., Bonzia flechtmanni sp. nov. and Dactyloscirus multiscutus sp. nov. are described from soil and leaf litter in Atlantic rainforest and Atlantic Araucaria forest in natural environments in São Francisco de Paula municipality, Rio Grande do Sul State, Brazil. In addition, the species Pulaeus quadrisolenidius Castro & Den Heyer 2009 and Lupaeus lectus Castro & Den Heyer (2009) are registered for the first time in this State.

Diversity, composition and phenology of araneid orb-weavers (Araneae, Araneidae) associated with riparian forests in southern Brazil

The Araneidae is a speciose family including web-spinning spiders that are very abundant in various terrestrial ecosystems. Several studies demonstrate that changes in vegetation surrounding rivers, streams and brooks affect the associated araneofauna. The aim of this research was to compare differences found in diversity (abundance and richness), composition and phenology of Araneidae spiders sampled in different habitats in four riparian forest catchments in southern Brazil. Samples were taken from riparian forests in four rivers of Rio Grande do Sul State: Piratini, Camaqua, Sinos and Maquine rivers, each in a different hydrographic basin. Samples were taken twice seasonally on each basin during two years, sampling the araneofauna of the tree-shrub strata with beating tray. Six transects were employed on each basin, two per habitat: edge with grassland, forest interior and river edge. Araneids totalled 20 genera and 65 species. Comparing riparian forests significant differences are found. Spider abundance differed among riparian forests as well as species richness. Overall, Piratini river riparian forest had the higher abundance and richness for Araneidae; the lower values were in Sinos river forest. The stronger degradation and fragmentation of the riparian forests of Sinos river probably influenced the results, with human disturbance gradients associated negatively to web building. We present data on the diversity of these spiders, which were very abundant in the riparian forest interior and very rich in species in the grassland/riparian forest edge. Species composition also differs among the studied habitats (the above plus river/riparian forest edge). For the most abundant species the phenological pattern across the seasons was also analysed.

Six new species and new records of the spider genus Chrosiothes from Brazil with the description of the female of Chrosiothes venturosus Marques & Buckup, 1997 (Araneae, Theridiidae, Spintharinae)

The spider genus Chrosiothes Simon, 1894 currently comprises 21 described species. Spiders of this genus are mainly known from the Neotropical Region, but are poorly studied in Brazil. In this paper six new species of Chrosiothes are described from Brazil: Chrosiothes diabolicus new species; Chrosiothes carajaensis new species; Chrosiothes cicuta new species; Chrosiothes murici new species; Chrosiothes decorus new species and Chrosiothes una new species. The female of Chrosiothes venturosus Marques & Buckup, 1997 is described and illustrated for the first time. Additionally, new records from Brazil are provided for C. perfidus Marques & Buckup, 1997 and C. niteroi Levi, 1964.

A new species and a new record of the spider genus Nesticus (Araneae, Nesticidae) from southern Brazil

The spider family Nesticidae includes 233 species in 13 genera and is distributed almost worldwide (World Spider Catalog, 2016). However, the family is still poorly known in the Neotropical Region. The genus Nesticus Thorell, 1869 comprises 132 species and seven subspecies and was described based on N. cellulanus (Clerck, 1757), from Europe (World Spider Catalog, 2016). Meridional South American species of Nesticus were revised by Ott & Lise (2002). More recently, Faleiro & Santos (2011) described a new species from the state of Minas Gerais, Brazil and Torres et al. (2016) a new species from the province of Salta, Argentina. Nowadays, Nesticus is represented by six species in Brazil: Nesticus brasiliensis Brignoli, 1979; Nesticus brignolii Ott & Lise, 2002; Nesticus calilegua Ott & Lise, 2002; Nesticus ivone Faleiro & Santos, 2011; Nesticus potreiro Ott & Lise, 2002 and Nesticus taim Ott & Lise, 2002 (World Spider Catalog 2016).

Two new species of orb-weaving spiders of the genus Larinia (Araneae, Araneidae) in meridional Brazil

The araneid genus Larinia Simon currently includes 56 species, eleven of them with New World distribution (World Spider Catalog, 2016). North American species of the genus were revised first time by Levi (1975) and South American species by Harrod et al. (1991). According to these authors there are four species known from subtropical South America (Larinia bivittata Keyserling 1885; L. montecarlo (Levi, 1988); L. t-notata (Tullgren, 1905); L. tucuman Harrod, Levi & Leibensperger, 1991) and also four species known from tropical South America (L. ambo Harrod, Levi & Leibensperger, 1991; L. directa (Hentz, 1847); L. lampa Harrod, Levi & Leibensperger, 1991; L. neblina Harrod, Levi & Leibensperger, 1991). According to Buckup et al. (2010) a total of 209 species of Araneidae are recorded for state of Rio Grande do Sul, including the three species L. bivittata, L. montecarlo and L. t-notata.

Influence of forest structure upon the diversity and composition of edaphic diplopods

Terrestrial diplopods are a diverse group of invertebrates with important ecosystem roles within soil communities, though information from the Neotropical Region is still scarce. The present study investigates the association between Diplopoda diversity and composition with vegetation structure, based on pitfall trap samples taken from three different successional vegetation formations in southern Brazil (primary forest, secondary forest, and Pinus monoculture). Samples were collected monthly from October 2000 to May 2002, resulting in 938 diplopod specimens, belonging to 5 families and 13 species. An emergent pattern of close connection between primary and secondary forests was represented by greater species richness and abundance than monoculture samples, a pattern not shared in terms of species composition. Two species, Oncoleptodesmus deflexus Schubart, 1958 and Catharosoma sp. were highly abundant among the sample areas, representing, respectively, 60 and 25% of the total abundance. By assuming a direct association between forest successional stages with habitat heterogeneity, we concluded that the diversity of millipedes is a reflection of habitat heterogeneity, species composition showed similar responses but independently from habitat heterogeneity and disturbance.

On the spider genus Thymoites in the Neotropical Region (Araneae, Theridiidae): nine new species, complementary descriptions and new records

The theridiid genus Thymoites Keyserling, 1884 is distributed worldwide. Spiders of this genus are mainly known from the Neotropical Region, but are poorly studied in Brazil. In this paper nine new species of Thymoites are described from Brazil, one from the state of Alagoas: Thymoites murici n. sp.; two from São Paulo: T. bocaina n. sp., T. ilhabela n. sp. and T. taiobeiras n. sp. from states of Minas Gerais and São Paulo; one from the state of Santa Catarina: Thymoites tabuleiro n. sp.; and, three from state of Rio Grande do Sul: Thymoites cristal n. sp., T. camaqua n. sp. and T. piratini n. sp., all based on males and females; and one from the state of Rio de Janeiro: T. pinheiral n. sp. based on male. The male of Thymoites puer (Mello-Leitão, 1941) and the female of T. melloleitaoni (Bristowe, 1938) are here described and illustrated for the first time. Additionally, new records from Brazil are provided for Thymoites ilvan Levi, 1964 for state of Santa Catarina; T. iritus Levi, 1964 for state of Goiás; T. piarco (Levi, 1959) for state of Amazonas; and, T. struthio (Simon, 1895) for Bolivia.