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Pseudotyphistes deinceps Cajade n. sp. is described from Uruguay based on males and females. Illustrations of somatic and sexual characters and a distribution map of the species is provided. In addition, new records of Pseudotyphistes pennatus Brignoli, 1972 for the country are presented. Data of the natural history and conservation status of both species are discussed.

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The taxonomy and systematics of the subfamily Allocosinae are poorly known, especially in South America. In the last century, several species have been described in genera from other subfamilies or transferred to them creating great confusion in the knowledge of Allocosinae. In this study we propose the new genus, Abaycosa gen. nov. to contain two species previously described, Orinocosa paraguensis (Gertsch & Wallace 1937) and Pardosa nanica Mello-Leitão 1941. Additionally, we propose two synonyms, Pardosa flammula Mello-Leitão 1945 as a junior synonym of Abaycosa nanica (Mello-Leitão 1941), comb. nov. and Alopecosa rosea Mello-Leitão 1945 as a junior synonym of Abaycosa paraguensis (Gertsch & Wallace 1937), comb. nov. The results of the phylogenetic analysis using molecular characters place Abaycosa in the subfamily Allocosinae, which is also supported by morphological data. Abaycosa can be distinguished from the remaining Allocosinae by the following characters: in males by the presence of only one distal macrosetae and a patch of flat setae on the tip of the cymbium, in females by the ventral position of the vulval chamber and by the short and stout stalk of the spermathecae.

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A new species of Chelodesmidae is described from northern Uruguay, Sandalodesmus joachimadisi n. sp. The new species differs from other congeners by particular features of the gonopods. Sandalodesmus joachimadisi n. sp. belongs to the iguazuensis species group. Photographs of the new species, data on its natural history and a geographic distribution map of all Sandalodesmus species are presented. A key to the species of Sandalodesmus is provided. The taxonomic relationships with other species of the genus are discussed.

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The immune response can be costly. Studies in several arthropod species have indicated a trade-off between immunity and other life-history traits, including reproduction. In sexually dimorphic species in which females and males largely differ in their life history strategies and related energetic demands, we can expect to find sex differences in immune functions. Sex differences in immunity are well documented in vertebrates; however, we largely lack data from invertebrate systems. Lytic activity, the immune system's ability to lysate bacteria and viruses, has been widely used as a proxy for the strength of the immune response in several invertebrates. With this in mind, we used the burrowing wolf spider Allocosa senex to test differences in lytic activity between females and males. We also studied whether digging behavior affects the immune responses in this species. While females of A. senex construct simple refuges where they stay during the day, males construct deep burrows, which they donate to females after copulation. In accordance with our hypothesis, females showed higher lytic activity compared with males, and those males who dug showed higher levels of lytic activity than those that did not dig. Furthermore, male body condition and lytic activity did not correlate with burrow length, a trait under female choice in this species. Our results show sexual dimorphism in lytic activity responses, which are likely related to differences in life-history strategies and energetic requirements of each sex in A. senex spiders.

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Biological corridors are connections which link habitats in a regional scale, allowing the gene flow between populations. The Uruguay River comprises riverside and insular riparian forests along subtropical to temperate zones passing through different biogeographic provinces. The aim of this study was to characterise the spider fauna from the Uruguay River islands highlighting their connection role for the spider community of riparian forest. Spiders were studied from surveys in a fluvial island of the southern course of the river with nine campaigns being carried out from September 2007 to September 2009. Three complementary collecting methods were used: G-Vac, night hand collecting and pitfall traps. A total of 58 samples were taken in each campaign. A total of 33 families, 145 species/morphospecies and 8 guilds were registered. Theridiidae and space web weavers showed the highest abundance and species richness. Web weavers were predominant in the spider community evidencing the importance of the forest vegetation heterogeneity in spider diversity. Fifteen species have been recorded for the first time for Uruguay. Additional data of previous surveys in the northern islands of the river were analysed and compared. Several species confirm the role of the Uruguay River as a biological corridor from the upper to lower course of the river. The riparian forests from the islands constitute a southernmost intromission of Paranaense biota between Chaco and Pampa regions along the river. The results obtained are an important input for the conservation of these areas. Knowing the biodiversity, as well as its dynamics and the flow of biota that exists in these environments, would allow planning the management from a regional point of view.

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The rice crop and associated ecosystems constitute a rich mosaic of habitats that preserve a rich biological diversity. Spiders are an abundant and successful group of natural predators that are considered efficient in the biocontrol of the major insect pests in agroecosystems. Spider diversity in different stages of the rice crop growth from eastern Uruguay was analysed. Field study was developed on six rice farms with rotation system with pasture, installed during intercropping stage as cover crop. Six rice crops distributed in three locations were sampled with pitfall and entomological vaccum suction machine. Sixteen families, representing six guilds, were collected. Lycosidae, Linyphiidae, Anyphaenidae and Tetragnathidae were the most abundant families (26%, 25%, 20% and 12%, respectively) and comprised more than 80% of total abundance. Other hunters (29%), sheet web weavers (25%) and ground hunters (24%) were the most abundant guilds. Species composition along different crop stages was significantly different according to the ANOSIM test. The results showed higher spider abundance and diversity along the crop and intercrop stages. This study represents the first contribution to the knowledge of spider diversity associated with rice agroecosystem in the country.

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Among ctenid spiders, ctenines comprise the most diverse subfamily. In this study, a new genus of Cteninae, Spinoctenus, is proposed to include the type species S. yotoco, sp. nov. Ten new species are also described: S. escalerete, S. pericos, S. eberhardi, S. spinosus, S. stephaniae, S. nambi, S. florezi, S. tequendama, S. chocoensis and S. flammigerus. Results of the parsimony and Bayesian phylogenetic analyses using morphological and behavioural characters indicate the monophyly of this genus, closely related to Phoneutria Perty, 1883 and Ctenus Walckenaer, 1805. This genus can be distinguished from the remaining Ctenidae by three unambiguous synapomorphies: embolus with folded process, tegulum with median process, and RTA curved internally close to the cymbium. A dispersal-vicariance biogeographical analysis of the genus in the Andean and Choco regions indicates the origin of Spinoctenus in the Western and Central Andean Cordilleras. From this region, three events of dispersal occurred to the other regions (one to the Choco and two to the Eastern Cordillera), which were subsequently followed by three events of vicariance, suggesting that dispersal and vicariance were equally important in shaping the current distribution patterns of Spinoctenus species. The discovery of this new genus containing a large number of new species in the Andean and Choco regions highlights the current poor knowledge of the Colombian biodiversity.

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Among ctenid spiders, ctenines comprise the most diverse subfamily. In this study, a new genus of Cteninae, Spinoctenus, is proposed to include the type species S. yotoco, sp. nov. Ten new species are also described: S. escalerete, S. pericos, S. eberhardi, S. spinosus, S. stephaniae, S. nambi, S. florezi, S. tequendama, S. chocoensis and S. flammigerus. Results of the parsimony and Bayesian phylogenetic analyses using morphological and behavioural characters indicate the monophyly of this genus, closely related to Phoneutria Perty, 1883 and Ctenus Walckenaer, 1805. This genus can be distinguished from the remaining Ctenidae by three unambiguous synapomorphies: embolus with folded process, tegulum with median process, and RTA curved internally close to the cymbium. A dispersal-vicariance biogeographical analysis of the genus in the Andean and Choco regions indicates the origin of Spinoctenus in the Western and Central Andean Cordilleras. From this region, three events of dispersal occurred to the other regions (one to the Choco and two to the Eastern Cordillera), which were subsequently followed by three events of vicariance, suggesting that dispersal and vicariance were equally important in shaping the current distribution patterns of Spinoctenus species. The discovery of this new genus containing a large number of new species in the Andean and Choco regions highlights the current poor knowledge of the Colombian biodiversity.

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Three species of the genus Allocosa Banks, 1900 from southern South America are redescribed: Allocosa alticeps (Mello-Leitão, 1944), A. brasiliensis (Petrunkevitch, 1910) and A. senex (Mello-Leitão, 1945). The female of A. senex is described for the first time and the species is revalidated. A new species, A. marindia sp. nov. from southern Uruguay and southern Brazil is described. The new species is distinguished by the flattened terminal apophysis of the male bulb and the conspicuous pointed projections on the posterior margin of the female epigynum. The species inhabits in sandy estuarine and oceanic coasts with psammophile vegetation.

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The spider genus Chrysometa Simon, 1895 comprises 138 species of small (3-5 mm) Neotropical orb-weavers spiders (Nogueira et al. 2011; World Spider Catalogue 2015) mainly associated with arboreal vegetation from intermediate to low altitude forests (Levi 1986). Males of Chrysometa differ from other tetragnathids by having the palpal tibial length approximately as long as its widest point; paracymbium articulated and with several apophyses located at both ends; male cephalic region narrower than in the female and having cymbial ectobasal and ectomedian processes. Females are diagnosed by having femora without trichobothria; abdomen covered with silver guanine patches; a flat epigynum and also by their fertilization ducts originating anteriorly and crossing over the spermathecae (Levi 1986; Alvarez-Padilla & Hormiga 2011).

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This study provides the first accurate records of Latrodectus geometricus C. L. Koch, 1841 for Uruguay and extends the known distribution of this species to the Southeastern region of South America. Data and figures of the genitalic morphology for the recognition of the species and natural history in this country are indicated. In Uruguay L. geometricus was mainly restricted to urban areas at the west of this country and it is associated with locations with high human activity.

Este estudio reporta los primeros registros precisos de Latrodectus geometricus C. L. Koch, 1841 en Uruguay y extiende la distribución conocida de esta especie para la región sureste de Sudamérica. Datos y figuras de las estructuras genitales para el reconocimiento de la especie e historia natural en este país son indicados. En Uruguay L. geometricus se encuentra principalmente restringida a áreas urbanas del oeste de este país y asociada a sitios con elevada actividad humana.

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Two new species of Mesabolivar González-Sponga are described, M. charrua sp. nov. and M. uruguayensis sp. nov. The male of Mesabolivar tandilicus Mello-Leitão is redescribed. Notes on the natural history of the studied species are presented.

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This study provides new records, geographical distribution extensions and a checklist of the current ctenids species in Colombia based on the review of four arachnological collections and published literature. A total of 15 new records for Ctenidae in Colombia are reported; nine of these species are new records for the country and the distribution of the remaining six is expanded. The genus Centroctenus Mello-Leitão, 1929 (C. ocelliventer Strand, 1909) is recorded for first time in Colombia and Cupiennius coccineus (F.O. Pickard-Cambridge, 1901) for South America. Due to the strategic geographic position of Colombia, which is a transition zone between Southern and Central American biotas, species inventories in different localities are important to fill distributional gaps. The number of known species of ctenids in Colombia is increased from 16 to 25 and these data will be useful for future studies in taxonomy, systematics and biogeography of this family.

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