Knowledge of the male genitalia of the Atemnidae is still limited, although several authors have previously contributed to our understanding of their structure. This study deals with the morphology and configuration of the male genital organs. Forty-four species belonging to 16 different genera have been investigated, including species of 4 genera of Miratemninae. Anatemnus longus Beier 1932 is synonymized with A. voeltzkowi (Ellingsen 1908), Paratemnoides ceylonicus (Beier 1932) is synonymized with P. pallidus (Balzan 1892), and P. minor (Balzan 1892) with P. nidificator (Balzan 1888). Tamenus equestroides (Ellingsen 1906) is moved to the genus Cyclatemnus. The genitalia of the investigated specimens are described and a general diagnostic description of the male genitalia of the family is given. The study reveals an overall uniformity in the genitalic configuration of the family, which indicates monophyly. With respect to the affinities with other families of the Cheliferoidea, the male genitalia suggest that the Atemnidae might be closer to the Withiidae than to the Cheliferidae or Chernetidae. Claimed differences between the Atemninae and Miratemninae are considered, but the morphology of the male genitalia does not support their division into two families. Comparison of species of the genera Anatemnus, Catatemnus, Oratemnus and Paratemnoides reveals greater variation within the genera than between different genera. This infers that the present systematic grouping of species does not reflect true phylogenetic relationships within the family.

Females of the orb-weaving spider Argiope bruennichi are very cannibalistic and regularly terminate copulations by aggressively attacking the male. Few males survive mating and they escape only if they mate no longer than 8 seconds on average. We speculated that the brief copulations of surviving males will not result in complete fertilization of all of a female's eggs and that multiple mating is necessary to compensate for that. Surprisingly, we found no difference in the proportion of hatched young in clutches of females that were experimentally assigned to mate once or twice. Even females that mated with one male for less than 10 seconds produced clutches with hatching rates no different than treatments with two matings. The question remains why males risk their lives by prolonging copulation duration. Possible causes and functions in the context of sexual selection are discussed.

In this study, the process of egg sac construction and the factors that determine fecundity in the spider Loxosceles intermedia were analyzed by comparing lab-reared females that had mated only once (n = 180 ovipositions) and females with unknown reproductive histories (n = 76 ovipositions). Among females known to have mated only once (n = 84), the number of viable eggs correlated positively with the duration of mating and with the age of the female at the time of fertilization and decreased significantly with successive ovipositions. In females with unknown (n = 36) reproductive histories, up to three fertile egg sacs were obtained from the same female with a third oviposition being observed only once. Oviposition was more frequent among larger females than smaller females. Among the reproductive variables evaluated, there were correlations between the number of eggs and the weight of the female spiders. More fertile eggs were laid by females with unknown reproductive histories than by females that mated only once. The existence of more stable environmental conditions, abundant food, and multiple fertilizations are probable factors which favor greater fertility of L. intermedia in urban Curitiba, located in southern Brazil, and can partly explain the success of this species in occupying this ecological niche.

The limited resources available to inventory biodiversity and conduct ecological monitoring requires efficient protocols for sampling with pitfall traps. Here we consider adding different length drift-fences to pitfall traps on spiders. Four different fencing treatments (no fence, or fence lengths of 2, 4 and 6 m) were evaluated in combination with three trap diameters (4.3, 7.0 and 11.1 cm). Three-way ANOVAs revealed no significant interaction effects between any combinations of fencing treatments, trap size or the spatial positioning of transects within the study site along which traps were arranged. Post-hoc tests showed fences significantly increased the abundance of individuals and richness of spider families, and species collected. Traps with 6 m fences were significantly higher in all of these variables than traps with 2 m fences. ANOSIMs revealed taxonomic composition differed significantly between fenced and unfenced traps at familial, and specific ranks. Among fenced traps, taxonomic composition was influenced primarily by trap diameter rather than fence length. ANOSIMs showed significant differences in taxonomic composition between each trap diameter for fenced traps. An optimal combination of fencing treatment and trap diameter was determined by constructing smoothed species accumulation curves for increasing numbers of traps. Four criteria were considered: equivalent numbers of traps, standardized cumulative trap circumference, standardized cumulative fence length (fenced traps only) and standardized cumulative handling time. For the same number of traps, 11.1 cm traps with 4 and 6 m fences collected the most species. At a standardized trap circumference, long fences were best, with all trap sizes catching similar numbers of species. When fence length was standardized, 11.1 cm traps with 2 or 4 m fences collected the most species. At a standardized handling time all traps caught very similar numbers of species, although most 11.1 cm diameter traps collected more species than other trap sizes and those with 4 m fences were most efficient. Given the similar performance of fenced and unfenced traps for standardized handling time, we outline reasons why unfenced traps may be best.

Male mating strategies are often deployed with regard to female maturity and receptivity, possibly in response to sperm utilization patterns on the part of the female. We examined the pattern of male residency with females during the mating period of the subsocial spider Anelosimus cf. jucundus (Araneae, Theridiidae). We first examined patterns of male cohabitation with naturally occurring penultimate instar and adult females in the field. Males were significantly more likely to be found in association with adult females, rather than with penultimate instar females. Penultimate instar and virgin adult females of known age were then placed into the field and monitored for residency by subsequently marked males. Males were, again, significantly more likely to be found in association with adult females, rather than with penultimate-instar females, although we were unable to determine if this pattern was due to differential arrival or to differential retention of males at adult female web sites. Aspects of A. cf. jucundus natural history, including duration of male residency and frequency of mating in the field, are provided for the first time. We discuss the patterns of male residency in relation to predictions based on sperm utilization patterns by female A. cf. jucundus spiders.

Chrysso nigriceps is redescribed and the male is described for the first time based on material from Colombia. Evidence for maternal care of juveniles in Chrysso is presented. This evidence is consistent with predictions based on phylogenetic analysis that maternal care is primitively present in the lost colulus clade, the lineage containing all social theridiids.

Heteropoda natans new species (Araneae, Sparassidae, Heteropodinae) is described from Borneo. Additional illustrations of the genitalia of H. hosei (Pocock 1897) are provided for comparison purposes. The lectotype of H. hosei is designated.

Three new species of Solifugae are described: Eremobates paleta from Mexico, is a member of the Eremobates scaber species group; Eremobates inkopaensis from California, U.S.A., is a member of the Eremobates palpisetulosus group; and Eremochelis albaventralis from Mexico is tentatively placed in the Eremochelis bilobatus group. The female of Branchia brevis Muma from Texas, U.S.A. is described for the first time.

Visual acuity in the sheet-web building spider Badumna insignis (L. Koch 1872) (Araneae, Desidae) was examined in relation to its microhabitat. We examined, using histological techniques, the major structural and functional features of the visual systems, including external and internal ocular organizations, resolution, sensitivity, focal lengths and the field of view for each eye. Badumna insignis showed little differentiation in its ocular arrangement from the presumed ancestral condition in spiders, with poor visual acuity and a small field of view. Resolution and sensitivity were low, particularly in the secondary eyes. The AM eyes were enhanced showing larger fields of view and higher sensitivity, resembling that of nocturnal uloborids. These eyes appear adapted for close-range recognition, due to short-range focus and good visual overlap.

A new species of scorpion from southern Brazil, Bothriurus pora, is described. The hemispermatophore of this species is unique within the genus, displaying a highly developed and extremely complex capsular region. External morphology and shape of the sperm packages show a close relationship with the Bothriurus bonariensis species group.

Phalangium opilio L. is a polyphagous predator frequently found in agricultural habitats. Although the potential importance of P. opilio's feeding on pests has been recognized, little is known about its activity patterns or its within-plant distribution in crops. We determined diel activity patterns and microspatial distribution in small, fenced arenas in soybean fields. The fenced arenas allowed us to track known numbers of particular size categories of P. opilio for each 24 h trial. Phalangium opilio were separated into the following categories based on body size and sex: medium-sized nymphs, large-sized nymphs, adult females and adult males. Medium-sized nymphs occupy the bottom and middle portions of plants regardless of time of day; they remain still during the day, but they exhibit leg palpating behavior from 21:00–01:00 h. Large-sized nymphs rest in the bottom and middle portions of plants during the day, but they walk and palpate on the ground from 21:00–01:00 h. Adult females rest in the bottom, middle and top portions of plants during the day, and they walk and palpate on the ground from 21:00–01:00 h. Adult males remain stationary in the bottom, middle and top portions of plants during the day, but they walk on the ground from 21:00–04:00 h.

Species placed in the genus Alcimosphenus are examined. Alcimosphenus licinus Simon 1895 is redescribed and validated. Alcimosphenus bifurcatus, A. rufoniger, A. boringuenae, Acusilas rufonigra and A. r. maculata are placed in synonymy. Alcimosphenus rubripleuris Mello-Leitão is transferred to Leucauge and redescribed.

Loxosceles intermedia is a medically important species that is abundant in Curitiba, Paraná State, Brazil. Knowledge of the postembryonic development of this species is fundamental for preventing bites by this species and for controlling its population size. In this report, postembryonic development (n = 212 spiderlings) was studied in the laboratory under ambient conditions of temperature and humidity with a standardized diet. The average duration of development (from emergence from the egg sac to maturity) was 356 ± 33 days (n = 189; range = 213–455). Spiders matured after 5^th–8^th molt, although most individuals matured after 7^th molt. The sex ratio was 1:1. The mortality in the laboratory was low, most pronounced in the 4^th and 5^th instars and was associated mainly with molting. The longevity of females (1176 ± 478 days) was significantly longer than it was for males (557 ± 88.6 days). The abundance of L. intermedia in Curitiba, city in the southern part of Brazil, is related to aspects of its life cycle, since a slow growth, low mortality, and greater longevity enhance the reproductive potential of the species.

Argyroneta aquatica is the only spider that spends its entire life under water, and is one of the few spiders in which males are larger than females. In this paper we investigated size dependent mate choice to clarify whether intersexual selection may be partly responsible for the reversed sexual size dimorphism (SSD) in A. aquatica. We found that females that only copulated once could produce up to six viable egg sacs, although the number of offspring decreased with each egg sac produced. Males are the more active sex in mate acquisition and females prefer large males as mating partners. However, females fled more often from males larger than their own size (SSD > 1) than from relatively smaller males (SSD < 1), although small males approached females more often than large males did. We found that males of A. aquatica may cannibalize females, which to our knowledge is the first account of such reversed sexual cannibalism in spiders. The extent of SSD (m > f) determined the likelihood of females being cannibalized. Apparently, avoidance behavior of females towards the preferred, large mating partners is related to the higher risk of being cannibalized. In A. aquatica, intersexual selection may stabilize male size at an optimum instead of directionally selecting for large body size.

New Zealand's endemic sand dune Latrodectus widow spider species, L. katipo and L. atritus, possess behavioral and physiological attributes likely to promote dispersal over large distances. Morphological, physiological and behavioral similarities between L. katipo and L. hasselti, an Australian endemic, suggest gene flow may occur across the Tasman Sea. In this study we examine intraspecific and interspecific genetic relationships within the ND1 gene region between L. katipo, L. atritus, L. hasselti and L. hesperus to assess whether the genetic evidence supports current taxonomic species designations. We found low interspecific pairwise distances among L. katipo and L. atritus populations, suggesting either introgression, incomplete lineage sorting, or that the current taxonomic distinction between the two species may be invalid. Parsimony and maximum likelihood analyses were inconclusive as to the relationships between the New Zealand Latrodectus species and the Australian L. hasselti. Low pairwise distances between L. hasselti and the New Zealand widow fauna indicated that L. katipo and L. atritus were not present in New Zealand before the fragmentation of Gondwana.

Hesydrus palustris Simon and H. habilis (O.P.-Cambridge) are redescribed. Four new species are described: H. caripito, H. yacuiba and H. chanchamayo are described only from females, and H. canar from both male and female specimens. Hesydrus monticola Chamberlin is a junior synonym of H. palustris. Hesydrus bucculentus Simon is a senior synonym of Trechalea cezariana Mello-Leitão. Hesydrus estebanensis Simon is transferred to the genus Enna O.P.-Cambridge. Hesydrus ornatus Mello-Leitão and H. bivittatus Mello-Leitão, known only from unidentifiable spiderling holotypes, are regarded as nomina dubia. Coincidence of geographic distributions of Hesydrus and Trechalea are noted.

Two new genera in the spider family Trechaleidae, Trechaleoides and Paratrechalea, are described. The females of the two known species of Trechaleoides, T. keyserlingi (F.O.P.-Cambridge) (type species) and T. biocellata (Mello-Leitão) are redescribed and their respective males are described for the first time; both are transferred from Trechalea. Two additional previously described species, also both transferred from Trechalea, are herein placed in the genus Paratrechalea are redescribed from their types, i.e., the female of P. ornata (Mello-Leitão) (type species) and male of P. wygodzinskyi (Soares & Camargo). The male of P. ornata is described for the first time. Four new species of Paratrechalea, P. longigaster, P. galianoae, and P. azul from females, and P. saopaulo from males and females are described. The immature specimen historically regarded as the holotype of Trechalea longitarsis (C.L. Koch) and regarded as a mistaken identity, is an unidentified species of Trechaleoides. The female holotype of Trechalea limai Mello-Leitão is confirmed to be lost but is considered to be a member of the genus Paratrechalea based on a study of the original description.

Ants prey on salticids, and encounters with weaver ants (Oecophylla smaragdina (Fabricius 1775)) appear to be especially dangerous for many salticids. In the Philippines, Myrmarachne assimilis Banks 1930 is a salticid that mimics Oecophylla smaragdina. We tested for the abilities of four categories of salticids, plus M. assimilis, to survive in the proximity of weaver ants. The four categories were: (1) myrmecomorphic (ant-like species other than M. assimilis); (2) myrmecophagic (ant-eating species); (3) myrmecophilic (a species that is either myrmecophagic nor myrmecophagic, but is known to associate with ants) and (4) ordinary (species that are neither ant-like nor ant-eating, and are not known to associate with ants). The hypothesis investigated here is that M. assimilis has, compared with other salticids, especially pronounced ability to survive in close proximity with this particular ant species. The individual salticids used in our experiments had not had previous contact with weaver ants or any other ants. When confined with groups of 10 weaver ants, the myrmecomorphic, myrmecophagic and myrmecophilic species survived significantly more often than ordinary salticids, but Myrmarachne assimilis survived significantly more often than all other categories. When kept with groups of 20 ants, there was a proportional decrease in the number of salticids that survived within each salticid category. However, few salticids survived when confined with groups of 40 ants, regardless of category.

A new technique for examining the exomorphology of the scorpion epicuticle is described that utilizes the fluorescent property of scorpion cuticle. Fluorescence of the scorpion exoskeleton under longwave ultraviolet light is a well known property previously only utilized for the capture or observation of scorpions at night. Fluorescence is an energy emission that is analogous to the secondary electron emissions utilized in electron microscopy to provide information about surface detail. This new technique is fast, inexpensive and non-destructive, and provides an alternative means of documenting of surface macrosculpture for the description and identification of scorpion species.

The history of spider ecology is discussed from its early beginnings in 1684 when the natural historian Martin Lister published his observations, to the post-war period up until 1973 when ecological spider research gathered momentum. While there have been many important observations since Lister, spider ecology appeared explicitly in the titles of papers only after the turn of the 20^th century. However, much of what was published up until the 1950s is of little scientific value because these works contained natural history notes and conjecture, not manipulative experimentation. The exception was a paper written in 1939 by Pontus Palmgren who was not an ecologist but paradoxically a functional anatomist with a particular interest in ornithology. His paper was in the spirit of Ernst Haeckel's original definition of ecology that was seen as synonymous with physiology, a legacy that was detected in many of the papers decades after Palmgren. However, there was little evidence that ecological theory was being tested. Instead, theoretical inputs were largely ignored with most spider ecologists preferring to pursue the somewhat circular interest of basic observational studies. Eventually after some considerable delay, Charles Elton's theories of the niche and succession fed into spider ecology but the papers were often weak and invariably flawed due to the absence of experimental manipulations. Notably, it was not until the 1950s, when the elegant experiments of Edwin Nørgaard who manipulated the system in order to understand the interactions between spiders and their environment, that scientific spider ecology began. Edwin Nørgaard should be credited as the father of ‘spider ecology’, although Matthias Schaefer and Sven Almquist also made important contributions to the field and should not be overlooked. These researchers employed manipulative techniques during a period in which this experimental approach was not widely used in spider ecology. I conclude this review with a look to the future and predict that model selection will become much more prevalent, although it will never replace manipulative experimentation. One outstanding issue that has remained since 1684 has been the gift of ecological theory to the wider scientific community. Although spider ecologists have received theoretical frameworks from other disciplines such as botany and entomology, they have never reciprocated although they are now well placed to do so.

Members of genus Ammoxenus are known predators of harvester termites (Hodotermes mossambicus). An A. amphalodes female was observed catching and paralyzing a termite in the field. The paralyzed termite was deposited in a silk sac with other paralyzed termites. This confirms that Ammoxenus spp. use different methods of catching and utilizing prey. Termites are either killed and fed upon or paralyzed and stored for feeding at a later time.

Females of Liocheles australasiae (Fabricius 1775) collected from a maleless population on Iriomote Island, Ryukyu, Japan, and separately reared in the laboratory have parthenogenetically produced five successive generations in seven years. Many individuals of the first generation collected in July 1994, gave birth to the second generations from 1994–1998, and some of the second generation gave birth to the third generation from 1997–1999. The fourth generations were born from 1999–2001, and the fifth generations were born in January–August 2001. Most females of all generations gave birth to about 20 neonates after approximately an eight-month pregnancy. In the ovary of a fourth generation female, as well as in those of most of the second generation females, there were growing embryos and a number of oocytes of various sizes, suggesting a possibility of the sixth generation or subsequent generations by parthenogenesis.

Little is known about how environmental conditions affect the relative efficacy of information present in chemical cues. The wolf spider, Pardosa milvina, responds to silk and excreta from a larger species of wolf spider, Hogna helluo, with effective antipredator behavior. We investigated whether wetting or heating chemotactile cues of Hogna helluo would reduce the amount of antipredator behavior displayed by Pardosa milvina relative to unmanipulated cues. Pardosa milvina showed less antipredator behavior on chemotactile cues that had been wetted then dried but did not respond differently in the presence of cues that had been heated and then cooled. The results suggest that, in the field, morning dew may degrade some of the cues deposited by H. helluo at night and reduce the ability of P. milvina to avoid predation. However, typical periods of daily heating of cues may not affect the efficacy of predator detection by P. milvina.

The first known male of the whip spider Phrynus asperatipes (Wood) is described from two oases and other regions of Baja California Sur, México. It differs from the females as follows: males have the carapace (6.5–7.9 mm) and abdomen (11.0–12.4 mm) smaller than females. Also on an average, the femora (2.3 mm) and tibiae (7.2 mm) of the antenniform legs are shorter than in females.

The parthenogenesis in Tityus trivittatus Kraepelin 1898, is confirmed for the first time, based on the progeny of three virgin females raised in isolation since their birth. The possible and occasional introduction of this species into Uruguay is discussed.

Allometric scaling is a powerful approach for studying the relationship between size, shape and function. We studied allometric slopes in Linyphia triangularis, measuring two male and one female genital characters and several male and female non-genital characters including male chelicerae that are used for fighting. As predicted from theory, genitalia had the lowest allometric values, fighting structures the highest.

We studied the natural history and social behavior of Paratemnoides nidificator (Balzan 1888) in a tropical savanna system. Females were responsible for all nymphal care. We observed, for the first time in pseudoscorpions, the occurrence of matriphagy behavior by the offspring. During conditions of food deprivation, the mother went out of the nest and passively awaited the protonymphs' attack, not reacting to the capture nor to the nymphs feeding on her body. We suggest that this extreme form of parental care, matriphagy, can reduce cannibalism among protonymphs and facilitate the evolution of social behavior in pseudoscorpions.