We present a refinement in the establishment of guilds in Neotropical spiders based on information assessed by assigning different levels of taxa identification, which allowed better descriptions of spiders' ecological diversities. The analyzed data were compiled from three inventories carried out in the States of Amazonas, Piauí and Paraíba, Brazil, representing three Neotropical biomes, Amazonia, Cerrado and Atlantic Forest. The natural history data were summarized in three dendrograms and 11 guilds are proposed. Owing to the great diversity of lifestyles among species into Corinnidae, Ctenidae, Miturgidae, Salticidae, Sicariidae and Theraphosidae, these families were divided into subgroups for the first time. The identification to sub-family level solved most of the problems in the guild establishment for Theraphosidae, Dipluridae, Miturgidae and Sicariidae. Owing to poor taxonomic and ecological knowledge, Salticidae was divided based on collecting method and taxonomic information, whereas Corinnidae, Ctenidae, Lycosidae and Pisauridae required identification to genus for more refined breakdowns.

Quatro fitofisionomias do Bioma Cerrado (mata dos cocais, mata seca semi-decídua primária, mata seca semi-decídua secundária e cerrado típico) na Fazenda Nazareth (Município de José de Freitas, Piauí) foram amostradas utilizando-se guarda-chuva entomológico e armadilhas de queda. Os indivíduos coletados a partir do protocolo estruturado e aqueles coletados previamente na área de estudo (amostragens ocasionais com armadilhas de interceptação e queda) foram identificados unificadamente. Um total de 1215 aranhas, 40 famílias e 114 espécies foram amostradas. Somente 38 espécies foram amostradas no durante o inventário padronizado. As curvas de riqueza de espécies estimadas variaram entre 47 (Bootstrap) e 124 (Chao2) espécies. A mata seca semi-decídua secundária exibiu maior abundância de aranhas (221 indivíduos) e riqueza em espécies (19 spp.). Este é o primeiro estudo comparando estas fitofisionomias, comuns no Norte do Piauí, e indubitavelmente ameaçadas pelo avanço da agricultura no estado. A riqueza em espécies de aranhas encontrada na Fazenda Nazareth é a segunda maior registrada para o Estado do Piauí.

This paper provides formal descriptions of some of the unnamed taxa that were included in the most recent molecular phylogeny of pholcid spiders (Eberle et al. 2018, BMC Evolutionary Biology, 18, 141). The focus is on new genera and on species that belong to recently revised genera. Eight new genera and 25 new species are formally described. In Arteminae, three new species are described in Artema Walckenaer, 1837: A. bahla sp. n., A. ghubrat sp. n., and A. dhofar sp. n. (all from Oman); five new species in Arnapa gen. n. (eastern Indonesia and New Guinea): A. arfak sp. n., A. tinoor sp. n., A. manokwari sp. n., A. meja sp. n., A. tolire sp. n.; and one new species in Chisosa Huber, 2000: C. caquetio sp. n. (Netherlands Antilles). In Ninetinae, three new monotypic genera are described: Pemona gen. n., with the type species P. sapo sp. n. (Venezuela); Pinocchio gen. n., with the type species P. barauna sp. n. (Brazil); and Magana gen. n., with the type species M. velox sp. n. (Oman). In Modisiminae, three new species are described in Chibchea Huber, 2000 (all from Brazil): C. amapa sp. n., C. santosi sp. n., and C. hamadae sp. n.; one new species in Psilochorus Simon, 1893: P. bromelicolus sp. n. (Brazil); and three new monotypic genera, all from Brazil: Arenita gen. n., with the type species A. fazendinha sp. n.; Kairona gen. n., with the type species K. selva sp. n.; and Saciperere gen. n., with the type species S. catuaba sp. n. In Pholcinae, a new monotypic genus is described: Giloloa gen. n., with the type species G. sofifi sp. n. (Indonesia); three new species in the genus Aetana Huber, 2005 (all from Indonesia): A. ternate sp. n.; A. mokwam sp. n.; A. ondawamei sp. n.; and two new species in the genus Panjange Deeleman-Reinhold & Deeleman, 1983 (both from Indonesia): P. thomi sp. n., and P. togutil sp. n. Artema ghubrat is a cave-dwelling species and the only (slightly) troglomorphic representative of Arteminae; A. dhofar is presumably the closest known relative of the pantropical and synanthropic A. atlanta. The new genus Arnapa is probably species rich in eastern Indonesia and New Guinea but poorly collected; its morphological delimitation from other Australasian Arteminae (Wugigarra Huber, 2001; Holocneminus Berland, 1942; Trichocyclus Simon, 1908) needs further study. Arnapa nigromaculatus (Kulczyński, 1911) comb. n. is newly transferred from Psilochorus. Pemona sapo is the first representative of Ninetinae from Venezuela. The genus Chibchea, previously known from the Andes only, is for the first time recorded from Brazil/lowland Amazonia. Arenita fazendinha is among the few species in Pholcidae with extremely reduced procursus and barely modified male chelicerae. Kairona selva is unique among Pholcidae for its brush of strong hairs on a median horn anteriorly on the ocular area. Saciperere catuaba is one of only four pholcid species currently known to occur both in the Amazon and in the Atlantic Forest; however, variation indicates that more than one species might be included. It is among the few spiders known to have asymmetric genitalia (antisymmetric female internal genitalia). The Brazilian Psilochorus bromelicolus is the first South American Psilochorus of which both sexes are adequately described; however, the assignment to Psilochorus is tentative. Aetana ternate has extremely elongated procursi and accordingly elongated female internal genitalia. Aetana ondawamei and A. mokwam have almost identical male pedipalps and chelicerae (except for size) but differ clearly in the female genitalia.

A new solifuge species in the genus Gaucha Mello-Leitão, 1924 and the ibirapemussu species-group is herein described based on males and females collected at Itacuruba, State of Pernambuco, and Jaicós, State of Piauí, both in Northeastern Brazil. Males of the new species can be readily recognized by having the movable finger MM and MSM teeth reduced and of similar size. The present finding raises to twelve the number of described species in the genus, five of which belong to the ibirapemussu species-group. Besides, a new locality record for the species Gaucha ibirapemussu (Carvalho et al., 2010) is here presented, along with an updated identification key for all Gaucha species.

Spiders are abundant in tropical ecosystems and exert predatory pressure on a wide variety of invertebrate populations and also serve as prey for many others organisms, being part of complex interrelationships influenced directly and indirectly by a myriad of factors. We examined the influence of biotic (i.e., prey availability) and abiotic (i.e., temperature, precipitation, relative humidity, real evapotranspiration) factors on species richness and abundance during a two-year period in the semiarid Caatinga vegetation in northeastern Brazil. Data were analyzed through partial autocorrelation functions, cross correlations, and a path analysis. A total of 2522 spiders were collected with beating tray, pit-fall traps, and malaise traps, comprising 91 species and 34 families. Spider abundance peaked in the rainy season. Our results suggest that total invertebrate abundance has a direct influence on spider richness and abundance, whereas the effects of precipitation were mainly indirectly related to most spider assemblage parameters. The increase in vegetation cover with the rainy season in the Caatinga provides more breeding and foraging sites for spiders and stimulates their activities. Additionally, rainfall in arid and semiarid ecosystems stimulated the activity and reproduction of many herbivore and detritivore invertebrates dependent on plant biomass and necromass consumption, leading to an increase in spider prey availability.

The global demand for different land-use practice commodities in the Amazonia is growing, and this region is increasingly affected by the impacts of land management. The aim of this study was to evaluate the influence of land-use intensification on soil spider assemblages from six different land-use systems in Colombia and Brazil. The systems were fallows after crops and pastures, forest, crops, pastures and plantations. Spider species richness and density decreased with increasing farming management intensity. A principal component analysis (PCA) showed forests and fallows were separated from systems with stronger anthropogenic soil disturbance. The relationships of ten spider guilds differed significantly between land-uses, suggesting that they can be a reliable parameter for studies of ecological indicators.