Azilia leucostigma Mello-Leitão 1941 considered by Mello-Leitão as a metine (Tetragnathidae), is transferred to the gnaphosoid family Gallieniellidae, as the type species of the new genus Galianoella. The obliquely depressed endites, the flattened irregular posterior median eyes, and the conical anterior lateral spinnerets retaining a sclerotized distal ring, among other characters, clearly place the new genus in the family Gallieniellidae. Galianoella leucostigma is the only gallieniellid so far recorded from the Americas. This species has a specialized ant-preying behavior. Ant-preying may prove to be characteristic for all the family, as it was suspected in the Madagascan Gallieniella; and it may be associated with the modified chelicerae typical of the family.

Three Brazilian species of the genus Paradossenus F.O. Pickard-Cambridge 1903 are included in this paper: Paradossenus minimus (Mello-Leitão 1940), whose holotype was located and is here redescribed; Paradossenus corumba new species is described from Mato Grosso do Sul, Brazil and preliminary data on its biology are presented. Morphological data and new records of P. longipes (Taczanowski 1874) are included.

We describe the histological structure of the eyes of Misumenops pallens (Araneae, Thomisidae). We have carried out frontal, sagittal and transverse histological sections of the eyes. All the eyes have cuticular and laminar corneas and lenses. The anterior median eyes have two cellular types in the rhabdom; the remaining eyes have three cellular types. The anterior median eyes have a dark pigmented U-shaped mark in the middle of the retina. The indirect eyes have a dark pigmented band divided by a grate tapetum. The pathway of the optic nerves is also described. Our results suggest that Thomisidae may be a close relative of the superfamily Lycosoidea.

The linyphiid spiders Oedothorax gibbosus (Blackwall 1841) and Oedothorax tuberosus (Blackwall 1841) were formerly described as separate species due to marked differences in prosomal structures of the males. During the last decade it was demonstrated that they are two forms of a single species. However, it remained to be shown whether the former species represent two distinct morphs or extremes of a continuum of variation. A morphometric examination of 246 alcohol-preserved specimens revealed that individual spiders can clearly be assigned to one of two forms. No intermediates were found, demonstrating that there are two distinct morphs.

A first attempt to homologize male palpal bulb structures of theraphosine spiders is made, with the aim of providing systematic characters. The morphology and distribution of palpal bulb keels of over 60 species in 27 genera of Theraphosinae is presented and discussed. Four basic groups of keels were recognized and a terminology was created to name them: prolateral inferior and prolateral superior keels, for the two more or less parallel keels found on the prolateral bulb face; apical keel, for the ventral keel located just before the apex of the embolus; subapical keel, for a keel located just before the apical keel; and, retrolateral keel, for the keel located on the retrolateral region, originating on the apical region and extending backwards. Other palpal bulb keels, apart from these four basic groups, as well as other structures, were found in some genera and/or species, constituting apomorphies for these groups.

A spider's calamistrum draws silk fibrils from its cribellum and helps combine them with supporting strands to form a cribellar prey capture thread. Despite the close functional association of these two features, this study shows that there is a great deal of variability in the ratio of cribellum width to calamistrum length. When the independent contrast method was used to examine these two features in 11 species representing seven families, no relationship was found. Likewise, no relationship was found among nine species representing seven genera of the family Uloboridae. Only among the 14 species of Mallos (Dictynidae) was calamistrum length directly related to cribellum width. This suggests that, above the genus level, differences in spinning behavior and morphological features such as leg length and abdomen size and shape influence the relationship of these two features.

Two high density lipoprotein fractions (HDL₁ and HDL₂) were isolated from the hemolymphatic plasma of the spider Latrodectus mirabilis (Holmberg 1876). For each, the hydrated density, the electrophoresis mobility of the apoproteins, and the lipid classes composition were determined. The HDL₁ fraction carried 80% of the total plasma lipids, which were predominantly composed of phospholipids, free fatty acids, and triacylglycerols. The apoprotein composition of this fraction showed two main bands of 90 and 103 kDa. The HDL₂ fraction was composed primarily of phospholipids, free fatty acids and cholesterol. This fraction contained hemocyanin as the principal apoprotein. When the HDL₂ fraction was separated into three subfractions, all of them contained hemocyanin, with the main subfraction containing the hexameric form of the respiratory pigment. With regard to triacylglycerol transport, lipid and apoprotein compositions and hemocyanin role in the lipid transport, these lipoproteins (HDL₁, HDL₂) show similarities and differences when compared to the two spider species already studied.

The effect of dietary pigments on abdominal color of juvenile spiders was examined in the laboratory using the flower-dwelling crab spiders Misumenops asperatus (Hentz 1847), Misumenoides formosipes (Walckenaer 1837), and Misumena vatia (Clerck 1757) (Thomisidae). Because these species lack hypodermal chromes, ingested prey pigments may show through the epidermis and affect opisthosomal coloration. Diet-induced color changes were restricted to the opisthosoma, and all three spider species responded similarly to dietary pigments. Opisthosomas of instars 2–4 fed red-eyed fruit flies turned pink, and the pink color faded back to the normal white over a period of 4–6 days. Opisthosomas of instars 5–7 fed red-eyed fruit flies remained white, as did opisthosomas of all instars fed white-eyed fruit flies (controls). In a field population of M. asperatus, 82% of spiders in July (instar 2), 93% of spiders in August (instars 3–4), and 8% of spiders in September (instar 5) had pink, orange, or brown opisthosomas. Yellow juveniles were also seen: 5% and 57% of M. asperatus observed in August and September, respectively, were yellow. Yellow juvenile M. formosipes were observed in the field as well. The yellow color did not result from dietary pigments, but was, rather, a morphological color change and included the prosoma and limbs, as well as the opisthosoma.

In the theridiid spider, Anelosimus studiosus, most juveniles remain in their natal web, forming temporary colonies in which individuals cooperate in web maintenance and prey capture until they disperse at maturity. There is natural variation in age at dispersal, and subadult spiders removed from their natal webs build webs and continue to develop. To explore the costs and benefits of delayed dispersal, we compared the rate of prey capture and developmental rate for individuals in colonies and those isolated at the fourth instar. Rate of prey capture by colonies increased with colony size and age; this result was driven primarily by the enhanced capture of large prey by larger and older colonies. The presence of juveniles increased the overall productivity of webs, an effect which remained after the juveniles were removed from the web. Despite the overall increase in prey capture, per-individual prey capture decreased with colony size. The variance in prey capture success decreased significantly with colony size, but not with colony age. Spiders in colonies captured more prey per juvenile than singletons experimentally dispersed at the fourth instar; however, this did not result in increased development rate of colonial juveniles over isolated juveniles. These data suggest that juvenile A. studiosus benefit from delayed dispersal by acquiring more resources and acquiring them more steadily. The productivity of webs of females whose juveniles were removed at the fourth instar remained higher than those of similarly aged females who never produced juveniles. This suggests that delayed dispersal of juveniles enhances the resources which the female could allocate to her next egg mass.

Two spider-boarding mantispids, Mantispa uhleri Banks 1943 and Climaciella brunnea (Say 1824), were found to be partitioning available spider egg resources in an Illinois woods based on vertical stratification. Mantispa uhleri was found to be phoretic on the philodromid Philodromus vulgaris (Hentz 1847), the salticid Metacyrba undata (De Geer 1867) and the anyphaenid Aysha gracilis (Hentz 1847) at levels of 75%, 26%, and 27% respectively. All of these spiders were collected from areas above the forest floor. In contrast, C. brunnea was collected from 19% of leaf litter-inhabiting lycosids of the genus Schizocosa. There was no host range overlap within the woods, but in a grassy field without appreciable stratification of vegetation adjacent to the woods, both M. uhleri and C. brunnea were found aboard the lycosid Rabidosa punctulata (Walckenaer 1837) at levels of 2% and 7% respectively. A single larva of Mantispa pulchella (Banks 1912) associated with an anyphaenid from the woodland sample was also collected in this study. Mantispids are far more common than has been previously supposed and are likely an important factor in spider population dynamics and the evolution of spider behavior.

This study investigates the indirect effects of primary productivity enhancement via fertilization, and the direct effects of environmental differences at two elevations, on the density and species richness of leaf-litter spiders. Litter was sampled in tabonuco forest (340–360 m elevation) and elfin forest (1051 m elevation) within the Luquillo Experimental Forest Long Term Ecological Research (LTER) site in Puerto Rico. Treatments consisted of three blocks with fertilization and control plots at both sites, and a one time removal of hurricane generated debris at tabonuco forest only. Treatments had no significant effect on spider density, species diversity, and species richness at either elevation. Elfin forest showed lower densities and lower species richness than tabonuco forest due to harsh environmental conditions. The thin litter layer and similar standing litter in the tabonuco forest suggest that spiders are limited by habitat, and also that they have successfully recolonized the debris cleared areas at this elevation. Harsh environmental conditions at elfin forest seem to be strong enough to counteract the effects of fertilizer addition on the measured variables. However, the high biomass of grasses in the fertilization plots at elfin forest could have caused an underestimation of spider densities. This study suggests that habitat availability is an important variable in bottom-up models for food web link control.

The same epigeic spider communities of North-west Jutland coastal heath habitats (Denmark, region Thy) initially surveyed by pitfall traps from 1977–79 were examined 20 years later (1997–98). The heath plots were open sandy areas growing into Calluna heath, and the more stable Erica, Calluna/Empetrum, Molinia vegetation types. They have changed vegetatively only a little in those 20 years from natural succession. Though the spider communities of all areas showed only minor changes from the passage of time, these were larger than the differences attributable to the different habitat types despite large differences in soil humidity and vegetation structure.

Habitat distribution patterns of five species of Tetragnatha Latreille 1804 were studied by analyzing 1163 one-hour samples collected at 17 focal sites representing 16 major biotic communities (habitats) in the Great Smoky Mountains National Park. Tetragnatha versicolor Walckenaer 1841 is a habitat generalist, being common over a wide range of elevations (520–1755 m) and in 10 of the 16 habitats, including seven forest habitats as well as wetland, high grass bald, and grassland habitats. Tetragnatha laboriosa Hentz 1850 is virtually restricted to non-wetland grassy habitats, T. elongata Walckenaer 1805 to streams, T. viridis Walckenaer 1841 to hemlock trees, and T. straminea Emerton 1884 to non-forested wetlands (marshes). Microhabitat segregation exists in the high grass bald community between T. versicolor (prefers trees and shrubs) and T. laboriosa (prefers herbs). Size frequency histograms of seasonal samples of T. straminea specimens indicate that this species has a one-year life cycle with six post-emergent instars, and that most individuals overwinter in the antepenultimate instar and mature and mate in May and June. Tetragnatha straminea is able to capture prey with or without using a web and adopts stick-like cryptic postures in three different contexts.

The relationship between the structure of spider communities and an index of hedge ecological quality (based on an analysis of vegetation architecture using vegetation diversity and foliage cover) was investigated. The comparison deals with six hedges each of low, medium and high ecological value. The species richness and species composition of dominant spiders was the same for hedges of different quality. Thus it is concluded that these two simple parameters cannot reflect the diversity of the hedge foliage. Indicating species of the differences between ecological quality of two hedges could be required among the groups of species absent from one type of hedge. However, the foliage orientation of the hedges may induce substitution of spider species; thus special attention must be paid to the foliage orientation when comparing the spider communities inhabiting the hedges.

The distribution, abundance, and diversity of wolf spider (Lycosidae) assemblages were investigated via pitfall trapping at three sites near Granite Reef Dam outside Phoenix, Arizona. These three sites featured different moisture and temperature regimes due to the dam, which diverts the Salt River into an urban canal system. Site 1 was a natural riparian area above the dam along the Salt River, Site 2 was adjacent to a man-made diversion canal, and Site 3 was adjacent to the dry riverbed below the dam. Four lycosid species were found at Site 1, with Pardosa vadosa Barnes 1959 dominating. Two species each, though very few total individuals, were found at Sites 2 and 3. Simpson's index of diversity (of lycosids and of all other terrestrial arthropods) was higher for Site 1 than for Sites 2–3. Prey availability was comparable among sites, but Site 1 had significantly higher relative soil moisture levels and less extreme substrate and air temperature conditions than did Sites 2 and 3. Spider abundance at each site was independent of prey availability, but instead depended chiefly upon moisture and temperature regimes among sites. The results suggest that wolf spiders experienced a significant effect from disturbance of their habitat by the dam, and that abiotic habitat attributes such as moisture and temperature may be more important for wolf spider abundance than prey availability alone in desert riparian systems.