Male Schizocosa ocreata (Hentz 1844) wolf spiders court females with multi-modal displays that include both seismic and visual components. The seismic components are thought to be ancestral whereas the visual components are thought to have been more recently derived. We here present evidence that, despite the evolution of elaborate visual display components in males, female S. ocreata remain able to derive sufficient information about males through the seismic display components alone. We compared the mating tendency of females courted by males in the light (seismic and visual components present) and in the dark (only seismic components present). With a sample of 79 pairs in each condition, pairs were not significantly less likely to mate when in the dark (62%) than when in the light (73%). While all males performed courtship, and latency from the release of males until the onset of courtship was similar in the light and in the dark, latency until mounting tended to be much longer in the dark. This may mean that it takes longer for females to gather the information required to accept a male in the absence of visual cues or may instead simply reflect the challenge of locating mates and orienting for mounting. Lighting conditions did not influence how long the male remained mounted, indicating that these wolf spiders lack the condition-dependent flexibility in copula duration that is found in some jumping spiders.

Two new species of wolf spiders in the Pardosa modica group (Araneae, Lycosidae) are described from North America: P. knappi from high-elevation lakeshores in the Sierra National Forest, California, USA, and P. pedia from prairie habitats in Saskatchewan, Canada.

The web construction behavior of Achaearanea tesselata (Keyserling 1884) was observed in the field and in captivity using suspended wire frames that allowed detailed observations. Construction included three stages: preliminary exploration during which lines were broken, reeled up, and replaced; construction of anchor lines and the upper tangle; and construction and then filling in of the sheet below the tangle. Repeated visits to the mouth of the retreat during tangle construction resulted in the apparent reinforcement of the few lines radiating from this area, a possible adaptation to sense the location of prey in the web, and to facilitate orientation of the spider to prey in the web. Filling in the sheet, which alternated with additions to the tangle, included two previously undescribed behavioral patterns: irregular wandering on the sheet and apparent attachments of the dragline using only the two legs IV to hold previous lines against the spinnerets. The spider needed 1–2 nights, working several hours each night, to make a complete tangle and sheet and added lines and extended both the tangle and the sheet on subsequent nights. Spiders adapted the shapes of their webs to their surroundings.

Among the trogulid harvestman Trogulus nepaeformis (Scopoli 1763) collected from sixty localities in Slovenia and northeastern Italy we found many individuals with evidence of old leg injuries. In a few localities, injured individuals accounted for 30% of the total. In non-autotomizing trogulids, in vivo damage to leg articles is characterized by rounded regeneration of the stumps with pseudonormal terminal chaetotaxy, in some cases including a secondary claw. This damage, probably caused by shrews, was considered appropriate for analysis of the regenerational asymmetry, or RA, of legs. In 169 available regenerated specimens, the lengths of preserved articles on the damaged legs were compared to those on the undamaged ones. In the damaged specimens, the range of leg article RA was significantly larger in comparison to undamaged specimens. This is considered to be a direct consequence of the regenerative processes in the leg stumps. The damage was most frequent in 2^nd leg, followed by 1^st, 3^rd and 4^th, indicating that such wounds were not stochastic, and probably appeared during the forward motion of the troguli. The stomach contents of 204 shrews were examined and the remains of T. nepaeformis were found in two individuals demonstrating for the first time that shrews do feed on this species.

Wolf spiders (Araneae, Lycosidae) are important predators at freshwater-forest ecotones where their distribution may be determined by their ability to respond to, amongst other factors, moisture and prey levels. The purpose of this study was to examine the movement of wolf spiders along a pond-forest boundary at Mountain Lake Biological Station, Virginia. We performed two mark-recapture studies at two temporal and spatial scales (4 h–20 d and 1 m–∼20 m, respectively) to determine the probability of movement by the spiders. Mark-recapture studies are useful for measuring individual movement, but, because of the difficulty of marking small arthropods, are not often used for spiders. This mark-recapture study showed the spiders moved very little over the temporal and spatial scale used: 0–54% per day chance of moving to the adjacent 1-m² plot around the pond and 0–2% per day chance of moving to the adjacent 1-m² plot to and from the pond. This finding is in contrast to other studies that have shown wolf spiders to completely exit a 900-m² quadrant within several days. We discuss possible causes of this low mobility and its implications for wolf spider distribution and abundance at the pond edge.

We investigated microhabitat selection in the Amazonian whip spider Heterophrynus longicornis (Butler 1973). The probability of finding individuals of this species increased according to the diameter of the trees. Moreover, there was a positive correlation between the size of adult individuals and the diameter of the trees on which they were found. Our results also provide quantitative support for a previous suggestion that H. longicornis prefers large trees bearing buttresses and burrows at the base where the individuals hide during daytime. Since whip spiders prefer large trees, the anthropogenic disturbance promoted by selective logging or the degeneration of the forest structure due to fragmentation and edge effect may have a negative effect on the spatial distribution and, consequently, on the density and population ecology of H. longicornis.

Jumping spiders have long been used as model organisms to study visual communication. However, recent studies documenting the presence of intricate multicomponent seismic songs during courtship displays suggest an important role of seismic communication as well. Given the relatively recent focus on seismic communication, the extent to which seismic songs vary among jumping spider species or even among populations remains poorly understood. Here, we use the extensively studied Habronattus pugillis Griswold 1987 complex to explore putative seismic song diversity among males from isolated populations. H. pugillis populations have been studied extensively because of the tremendous diversification of male visual secondary sexual ornaments observed among adjacent mountain-top populations in southeastern Arizona (“sky islands”). Here, we aim to explore putative parallel patterns of diversification in seismic courtship songs between different sky island populations. Using laser vibrometry, we examined in detail the songs of three mountaintop populations (Atascosa (AT), Santa Rita (SR), and Santa Catalina (SC)) and observed an extraordinary diversity of songs and song types among these three populations. Large differences were seen in both the temporal and spectral properties of male seismic songs. In addition, we observed differences in song complexity between populations with some populations having “simple” songs (1 component) and others having “complex” songs (3 components). We also present preliminary data from four additional populations (Galiuro (GA), Huachuca (HU), Mule (MU), and Patagonia (PA)). Results from this study suggest that the diversification of male visual signals observed among populations of H. pugillis finds a counterpart in male seismic songs

We report on the structure of the small-subunit ribosomal RNA (18S rRNA) sequence from Hyptiotes gertschi (Araneae, Uloboridae), which is the largest 18S gene sequenced in any arachnid to date. We compare this remarkable sequence to those from a range of other spiders and arachnids, and develop base-pairing models of its insert regions to determine its overall secondary structure. The H. gertschi sequence of 1902 bases is 86 nucleotides longer than any comparable spider sequence and contains 5 inserts between 5 and 28 bases in length, all at regions characterized as among the most variable in eukaryotic 18S genes. Inserts were also found in one of these variable regions in published sequences of 3 species of hard ticks (Acari, Ixodidae). Other arachnid taxa were remarkably uniform in 18S primary sequence length, ranging from 1802 to 1816 nucleotides. Thermodynamic modeling of the H. gertschi inserts suggests they are largely self-complementary, extending the stem portions of the variable regions.

Amblypygids have modified front legs that are not used for locomotion, but rather to probe the environment in the manner of antennae. These elongate, motile sense organs are referred to as antenniform legs. We have found remarkable replication in structure and function of giant neurons in the antenniform leg of the amblypygid Phrynus marginemaculatus C. L. Koch 1841 when compared with other amblypygids. These neurons have such large diameter axons (several μm) that their action potentials can be recorded outside the cuticle. Their cell bodies are found in the periphery, in the distal-most segments of the antenniform leg, centimeters away from the central nervous system. Primary afferents from sense organs on the antenniform leg synapse onto some of the giant fibers in these distal segments of the leg. Standard histological techniques and a novel whole mount preparation were used to identify the location of giant cell bodies within the antenniform leg. We found several new cell bodies in segments 10–20, three of which were predicted by previous electrophysiological studies of another amblypygid, Heterophrynus elaphus Pocock 1903. Electrophysiology was used to show that the structure and function of four of the giant neurons, GN1, 2, 6, and 7, is very similar in P. marginemaculatus and H. elaphus. Heterophrynus elaphus inhabits humid tropical forests in South America while P. marginemaculatus individuals were collected from a pine rock hammock in the Florida Keys, USA. The similarity of findings in species with such distinct habitats suggests that the giant neurons are required for basic neuromechanical operation of these extended limbs, and are not subject to intense selection via ecological factors.

The new species Pachychernes tamaulipensis is described from all free-living stages collected in nests of the packrat, Neotoma micropus, in Tamaulipas, México. This species is related to P. shelfordi, P. zehorum, P. attenuatus and P. baileyi; all of them form a coherent group. The distribution of the pseudoscorpions in the different components of the nests is analyzed.

Resumen. Se describe la nueva especie Pachychernes tamaulipensis considerando todos sus estadios de desarrollo, los cuales fueron colectados en nidos de Neotoma micropus en Tamaulipas, México. Esta especie está relacionada P. shelfordi, P. zehorum, P. attenuatus y P. baileyi, los cuales forman un grupo coherente. Se analiza la distribución de los pseudoescorpiones en los diferentes componentes del nido.

A new species, Vaejovis atenango, belonging to the V. punctipalpi group is described from southern Mexico; this group was previously only known from the North American deserts in the USA and northern Mexico. This geographically discontinuous distribution is similar to that observed in the scorpion genus Hadrurus Thorell 1876 (Scorpiones, Iuridae).

RESUMEN. Se describe una nueva especie, Vaejovis atenango, del grupo V. punctipalpi del sur de México; este grupo solo se conocía de los desiertos de Norte América en los EE.UU. y el norte de México. Esta distribución geográfica discontinua es similar a la del género de alacranes Hadrurus Thorell 1876 (Scorpiones, Iuridae).

Two new spiders, Quamtana huberi new species (Pholcidae) and Selenops sp. indet. (Selenopidae), are described from Lowermost Eocene (Ypresian) amber from Le Quesnoy, Oise department, Paris Basin, France. Both specimens represent the oldest known fossils of their respective families. This is the first fossil record of the extant genus Quamtana, extending its known geological range by 53 Mega-annums (Ma). The known geological age of Pholcidae is extended by approximately 5–10 Ma from that of its previous oldest occurrence in Baltic amber. The known age of Selenopidae and the extant genus Selenops are extended by approximately 30 Ma, from their previous oldest occurrence in Dominican Republic amber. The distribution of extant species from these genera suggests the inclusions in amber from the Paris deposit have close affinities with the African fauna.

The armored spider Monoblemma muchmorei Shear 1978 occurs in the wet subtropical forest of the Caribbean National Forest, Luquillo, Puerto Rico. It is found almost entirely in bamboo litter between 100 and 110 m in elevation and shares this habitat with a number of other species of spiders, ants and other small arthropods. The two sexes come together with no evidence of prior courtship, mate, and may remain in copula for many hours. A small decorated egg sac is produced with only one egg in each sac. The female tends the unusually large spiderling for a week or more and appears to offer some protection from other small invertebrates. For reasons not understood, second instar spiders suffered a high mortality rate, up to 70%. In captivity, the adults may live for eight months or more. Observations on the predator-prey interactions among M. muchmorei and other small invertebrates are reported. At least 30 species of spiders in 16 families are found associated with M. muchmorei in the bamboo litter.

A new genus of Ideoroncidae, Pseudalbiorix, is described from Central America, and is found to consist of four species: the type species P. reddelli (Muchmore 1982), new combination from southern Mexico, P. veracruzensis (Hoff 1945), new combination from Belize, Guatemala and southern Mexico, and P. muchmorei Barba & Pérez, new species and P. armasi Barba & Pérez, new species from western Cuba. Pseudalbiorix reddelli and P. veracruzensis are transferred from the genus Albiorix. Members of this genus differ from all other ideoroncids principally in the morphology of the chelal externo-distal condyle. All post-embryonic stages of P. reddelli are described.

The long legs, compact body and hanging posture of many harvestmen are unique among terrestrial animals, but no quantitative analyses of locomotion have been conducted to determine if this extreme morphology is associated with novel mechanisms of locomotion. Here we have undertaken a three-dimensional kinematic analysis of running Leiobunum vittatum (Say 1821) using field-by-field analysis of high-speed video. The center of mass of harvestmen was found to undergo vertical and transverse displacements of unprecedented magnitude, but the pattern of displacements was consistent with those predicted by general models of energetic efficiency and dynamic stability of pedestrian locomotion. Because these models assume substantial roles for elastic energy storage in leg elements, elasticity is probably an important component of the locomotor mechanism in harvestmen, and we identify two skeletomuscular elements as possible springs.

A lectotype is designated for Centruroides elegans edentulus Werner 1939, originally described from Cuernavaca, Morelos, Mexico. It is declared a junior synonym of Centruroides limpidus (Karsch 1879).

Suffasia attidiya was previously known only from females. This paper describes males collected from the type locality. Males of S. attidiya can be recognized by the following combination of characters: tibia with stout retrolateral apophysis; triangular dorsal cymbial extension; cymbial flange attached at its center to the cymbium; embolus with a base positioned under the proximal part of tegulum; long tapering, outwards pointing tegular apophysis.

Cobweb spiders (Theridiidae) exhibit a rich variety of web designs. Current knowledge of theridiid web architecture and evolution indicates that theridiid web design shows high within-taxon diversity and frequent convergence. Here we redescribe Achaearanea hieroglyphica (Mello-Leitão 1940), including the first description of the male, and document in this species (1) an unusual web design and (2) two dramatically different type of webs.

Preliminary observations on Helvibis thorelli (Theridiidae) in French Guiana suggest a typical subsocial behavior in this species, with nests consisting of a mother and her offspring who collaborate in prey capture. Communal feeding occurs over several juvenile instars. Subsociality has previously been described in three theridiid genera (Achaearanea, Anelosimus, Theridion) and predicted to occur in further genera of the subfamily Theridiinae. Our findings support this prediction and have important implications for comparative studies as they add another independent observation of social behavior: current phylogenetic knowledge implies subsociality evolved independently in each of these genera.

Two new synonyms are established in Salticidae: Menemerus falconensis Schenkel 1953 is designated as a junior synonym of Freya infuscata (F.O. Pickard-Cambridge 1901); and Phiale albovittata Schenkel 1953 is designated as a junior synonym of Freya perelegans Simon 1902. In addition, the new combination Cotinusa furcifera (Schenkel 1953) is proposed for Breda furcifera Schenkel 1953.

Field observations suggested that the spider Enoploctenus cyclothorax (Bertkau 1880) avoids preying on the harvestman Mischonyx cuspidatus (Roewer 1913). The objectives of this study were to test the degree to which this prey avoidance occurred, and to test the effects of starvation on predation rates. Laboratory prey-predator encounters showed that 77.8% of the spiders rejected the harvestmen even after severe starvation, dying after sharing the same terrarium with a harvestman for 68.6 ± 21.8 days. Two spiders fed on the harvestmen, but only after one week. In comparison, crickets given to the control group were all consumed after 13 hours. Prey recognition and subsequent avoidance, without conspicuous exudation of the scent glands (92.9% of the cases), occurred only after the harvestman was touched. We conclude that adult E. cyclothorax do avoid preying on M. cuspidatus, even after severe starvation, suggesting that the latter is recognized by the former by its chemical properties.

Samples from Palpigradi, Ricinulei, and Schizomida were examined by energy dispersive X-ray spectroscopy (EDS) for the presence of metallic elements in cuticular structures. Manganese was found in Ricinulei while zinc was found in Palpigradi and Schizomida. When presence or absence of zinc is superimposed on a cladogram of arachnid orders, its absence in the Acaromorpha (Acari Ricinulei) appears to be a derived condition. Similarly the absence of manganese in the Uropygi (Schizomida Thelyphonida) may be synapomorphic as well.