Is Xysticus kochi (Araneae: Thomisidae) an efficient indigenous biocontrol agent of Frankliniella occidentalis (Thysanoptera: Thripidae)?

According to the present practice of Hungarian greenhouse sweet pepper production, only exotic agents are used for biological control purposes against thrips pests. The suitability for biological control of the second instars of an indigenous species, the common crab spider, Xysticus kochi Thorell (Araneae: Thomisidae) was tested on thrips species, Frankliniella occidentalis (Pergande) and Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) using a cage set-up on greenhouse sweet pepper plants. Effects of introducing second instars of X. kochi on thrips infested plants were judged by assessing the degree of aesthetical damage, the commercial value of the fruits (degree of economic loss) and the quality composition of the harvested peppers. The estimated damaged surface unit was significantly lower in control plants than in plants infested by F. occidentalis. A significant effect of the spider introduction was observed in all of the pepper quality indicators applied. We suspect that direct Xysticus predation or any other predator-induced effect resulted in reduced levels of damage on harvested peppers. However, further investigation is needed to detect the origin (e.g., predation and non-predation effects) of the suppression of thrips damage. Our results suggest that X. kochi could be an effective component of greenhouse antagonistic fauna and the application of mulch may encourage the effectiveness of spiderlings. An erratum to this article can be found at     

Phantoms of Gondwana?—phylogeny of the spider subfamily Mynogleninae (Araneae: Linyphiidae)

This is the first genus‐level phylogeny of the subfamily Mynogleninae. It is based on 190 morphological characters scored for 44 taxa: 37 mynoglenine taxa (ingroup) representing 15 of the 17 known genera and seven outgroup taxa representing the subfamilies Stemonyphantinae, Linyphiinae (Linyphiini and Micronetini), and Erigoninae, and a representative of the family Pimoidae, the sister‐group to Linyphiidae. No fewer than 147 of the morphological characters used in this study are new and defined for this study, and come mainly from male and female genitalia. Parsimony analysis with equal weights resulted in three most parsimonious trees of length 871. The monophyly of the subfamily Mynogleninae and the genera Novafroneta, Parafroneta, Laminafroneta, Afroneta, Promynoglenes, Metamynoglenes, and Haplinis are supported, whereas Pseudafroneta is paraphyletic. The remaining seven mynoglenine genera are either monotypic or represented by only one taxon. Diagnoses are given for all genera included in the analysis. The evolution of morphological traits is discussed and we summarize the diversity and distribution patterns of the 124 known species of mynoglenines. The preferred topology suggests a single origin of mynoglenines in New Zealand with two dispersal events to Africa, and does not support Gondwana origin.     

Effects of anthropogenic factors on spider communities (Arthropoda: Araneae) in Chréa National park (Blida,Algeria)

Chréa National Park, one of the 11 national parks in Algeria, is natural and diverse but under different pressures: urbanisation, fires caused by the high flux of visitors. Several ecological and systematic studies have been conducted on the Araneae, the most important epigeal fauna, but no attention was given to the anthropogenic parcels of the Park. To assess the effects of urbanisation and fires on the ecology of this fauna, spiders were collected monthly for 2 years, using ‘Pitfall’ traps in three disturbed stations: burned, urbanised and reforested and three natural sites as control. In total, 1,476 specimens were sampled (19 families, 42 genera and 68 species). Zodarion algericum was the dominant species (13.25%), particularly in the burned station. Mann–Whitney U test showed a significant difference between urbanised and nonurbanised sites in contrast to other ones and no significant differences with the control. Our results show that fires transform the forest into a mosaic of habitats, with open gaps of different stages of succession. In addition, the reforestation of cedars without any agricultural practices has no negative effects on the Park. No loss of biodiversity was observed; this would encourage the restoration of the forest to protect its fauna and flora.     

Redescription of “Nesticus” citrinus (Taczanowski, 1874) (Araneae,Araneoidea) from French Guyana

“Nesticus” citrinus, a species originally placed in Theridion is redescribed based on the syntype series composed by 7 females and a lectotype is designated. All syntypes have broken emboli in their epigynes. Taxonomic position of “Nesticus” citrinus is briefly discussed and its belonging to Nesticidae is doubted.     

The genus Myrmarachne (Araneae,Salticidae) in?Flores,Indonesia

Two new species of the genus Myrmarachne are described (Myrmarachne acutidens sp. n., Myrmarachne epigealis sp. n.), and Myrmarachne macrognatha and Myrmarachne melanocephala are redescribed from Flores specimens. The females of Myrmarachne macrognatha are recorded for the first time.     

How Did the Spider Cross the River? Behavioral Adaptations for River-Bridging Webs in Caerostris darwini (Araneae: Araneidae)

Background

Interspecific coevolution is well described, but we know significantly less about how multiple traits coevolve within a species, particularly between behavioral traits and biomechanical properties of animals'' “extended phenotypes”. In orb weaving spiders, coevolution of spider behavior with ecological and physical traits of their webs is expected. Darwin''s bark spider (Caerostris darwini) bridges large water bodies, building the largest known orb webs utilizing the toughest known silk. Here, we examine C. darwini web building behaviors to establish how bridge lines are formed over water. We also test the prediction that this spider''s unique web ecology and architecture coevolved with new web building behaviors.

Methodology

We observed C. darwini in its natural habitat and filmed web building. We observed 90 web building events, and compared web building behaviors to other species of orb web spiders.

Conclusions

Caerostris darwini uses a unique set of behaviors, some unknown in other spiders, to construct its enormous webs. First, the spiders release unusually large amounts of bridging silk into the air, which is then carried downwind, across the water body, establishing bridge lines. Second, the spiders perform almost no web site exploration. Third, they construct the orb capture area below the initial bridge line. In contrast to all known orb-weavers, the web hub is therefore not part of the initial bridge line but is instead built de novo. Fourth, the orb contains two types of radial threads, with those in the upper half of the web doubled. These unique behaviors result in a giant, yet rather simplified web. Our results continue to build evidence for the coevolution of behavioral (web building), ecological (web microhabitat) and biomaterial (silk biomechanics) traits that combined allow C. darwini to occupy a unique niche among spiders.     

Mineral congregations, “spherites” in the midgut gland ofCoelotes terrestris (Araneae): Structure,composition and function

Summary Spherites in the digestive and secretory cells of the midgut gland of the agelenid spiderCoelotes terrestris were studied by electron microscopy and histochemical methods. Spherites measured 1–6 m in diameter and were characterized by alternating layers of electron dense and electron lucent material. The main-components of spherites were calcium phosphates and calcium carbonates. Guanine and barium, as well as aminopeptidase and alkaline phosphatase were also present. The matrix consisted of proteins and carbohydrates. Numerous spherites were found together with excretory products within the excretory vacuoles of the digestive cells.Spiders fed with food containing lead, showed deposition of the metall in the spherites. It is then proposed that spherites, aside from their role in storing calcium and other ions, may function in detoxification of heavy metals.     

Un complément à l'appareil séricigène des Uloboridae (Araneae): Le paracribellum et ses glandes

Summary In several genera of Uloborid spiders the median spinnerets are provided with a cluster of specialized spools. These spools are comparable in structure with those of the cribellum, but far fewer in number. We name the newly described formation of spools the paracribellum. The histological features of the associated glands are similar to those of the cribellar glands; histochemically they seem closer to the pseudoflagelliform glands. It is suggested that paracribellar fibers impart consistency to the fibrillar secretion of the cribellum.     

A review of the spider genus Haplodrassus Chamberlin, 1922 in Crimea (Ukraine) and adjacent areas (Araneae, Gnaphosidae)

Eight species of Haplodrassus are recorded from Crimea: Haplodrassus bohemicus Miller & Buchar, 1977; Haplodrassus dalmatensis (L. Koch, 1866); Haplodrassus isaevi Ponomarev & Tsvetkov, 2006; Haplodrassus minor (O. P.-Cambridge, 1879); Haplodrassus kulczynskii Lohmander, 1942; Haplodrassus pseudosignifer Marusik, Hippa & Koponen, 1996; Haplodrassus signifer (C.L. Koch, 1839) and Haplodrassus umbratilis (L. Koch, 1866). The occurrence of Haplodrassus cognatus (Westring, 1861) in Crimea has not been confirmed. Haplodrassus bohemicus is a new species record for the Crimean fauna. Haplodrassus pseudosignifer is a new species record for Crimea and Ukraine as a whole, with Crimea as the westernmost point of its distribution range. Haplodrassus invalidus is recorded for the first time for the fauna of Azerbaijan, Caucasus and the former Soviet Union. Azerbaijan is the easternmost point of its known distribution range. All Crimean Haplodrassus species have only one peak of activity of adult specimens during the year. In Crimea we found syntopically two closely related species Haplodrassus dalmatensis and Haplodrassus isaevi in two localities (Sudak Distr., 10 km W Sudak, Mezhdurechie Vill., steppe; and Feodosiya Distr., Karadag Nature Reserve, steppes). These species differ in their phenology. The reproductive period of Haplodrassus dalmatensis isin May-July, and that of Haplodrassus isaevi occurs is in October-December. These phenological differences probably represent an additional mechanism of reproductive isolation between the two species. Diagnostic drawings are provided for all mentioned species as well as for Haplodrassus deserticola Schmidt & Krause, 1996 and Haplodrassus pugnans (Simon, 1880).     

Why is Madagascar special? The extraordinarily slow evolution of pelican spiders (Araneae,Archaeidae)

Although Madagascar is an ancient fragment of Gondwana, the majority of taxa studied thus far appear to have reached the island through dispersal from Cenozoic times. Ancient lineages may have experienced a different history compared to more recent Cenozoic arrivals, as such lineages would have encountered geoclimatic shifts over an extended time period. The motivation for this study was to unravel the signature of diversification in an ancient lineage by comparing an area known for major geoclimatic upheavals (Madagascar) versus other areas where the environment has been relatively stable. Archaeid spiders are an ancient paleoendemic group with unusual predatory behaviors and spectacular trophic morphology that likely have been on Madagascar since its isolation. We examined disparities between Madagascan archaeids and their non‐Madagascan relatives regarding timing of divergence, rates of trait evolution, and distribution patterns. Results reveal an increased rate of adaptive trait diversification in Madagascan archaeids. Furthermore, geoclimatic events in Madagascar over long periods of time may have facilitated high species richness due to montane refugia and stability, rainforest refugia, and also ecogeographic shifts, allowing for the accumulation of adaptive traits. This research suggests that time alone, coupled with more ancient geoclimatic events allowed for the different patterns in Madagascar.     

New species of Pseudopoda J?ger, 2000 from Southern?China (Araneae,Sparassidae)

Four new species of the huntsman spider genus Pseudopoda Jäger, 2000 are described from Southern China: Pseudopoda acuminata sp. n. from Suiyang County, Guizhou Province, P. emei sp. n. from Emei Mountain, Sichuan Province, P. lacrimosa sp. n. from Fugong County and Tengchong County, Yunnan Province, and P. robusta sp. n. fromJinyun Mountain, Chongqing Municipality.     

Is inaccurate mimicry ancestral to accurate in myrmecomorphic spiders (Araneae)?

Batesian mimicry, in which a palatable organism resembles an unpalatable model, is widespread among taxa. Batesian mimics can be classified based on their level of accuracy (inaccurate or accurate). Using data on defensive strategies in more than 1000 species of spiders I investigated whether inaccurate myrmecomorphy is ancestral to accurate myrmecomorphy. I classified 233 myrmecomorphic species into four accuracy levels based on morphology, from poor inaccurate mimics to very accurate ones. I found that myrmecomorphy has evolved independently in 16 families and 85 genera. On the family‐level phylogeny, the occurrence of myrmecomorphy is confined mainly to families branching later on the tree, from the RTA clade. On the generic‐level phylogenies in Corinnidae and Salticidae, myrmecomorphy is not only of derived origin. Estimated ancestral state was non‐mimetic in Salticidae and poor inaccurate myrmecomorphy in Corinnidae. Thus, inaccurate myrmecomorphic spider mimics seem rather ancestral to accurate but additional analysis on species‐level phylogenies is needed to support this conclusion. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 97–111.     

Effects of a Four-Year Ecological Cultivation on Spider Coenoses (Arachnida,Araneae) on the "Ökohof Seeben" In Halle (Saale)

From 1994 to 1997 investigations have been carried out on fields of the "Ökohof Seeben" in Halle (Saale), refering to long-term effects of ecological agriculture on fauna, flora and soil. For the sampling of the epigeic fauna, pitfall traps were used. The purpose was to examine the effect of the changes in management on spiders for example. The influence of field size, edge-structures and different crops on species- and individual-numbers was studied. The question was, whether ecological agriculture results in an increasing biodiversity overviewed over years. In 4 years, on 6 fields, 190 species of spiders (82,202 adults spiders) could be proved, among them 32 species endangered in Sachsen-Anhalt and 28 species endangered according to the Red-Data-Books of Germany. The species numbers in the edge-biotops were nearly twice the numbers in the fields. The activity density of pioneer species (for example Oedothorax apicatus ) decreased rapidly on all fields. As a whole species numbers, and also the number of seldom species, were higher on the small fields than on the large fields lying in a poor structured environment. On the large fields some species, especially some Gnaphosidae and Lycosidae were missing in the first two years, but could be proved in the later years. Increasing numbers of species bigger in size and also more balanced dominance structures could be observed in the later years of investigation. In the fields the Linyphiidae species O. apicatus, E. atra, E. dentipalpis, M. rurestris, L. tenuis, P. microphthalmum, A. humilis and the Lycosidae P. agrestis and P. prativaga were dominant. Other species, like D. concolor, B. gracilis, H. signifer, P. juncea, T. ruricola, D. pusillus, X. kochi, O. claveata, P. degeeri, P. palustris, R. lividus prefered the adjacent boundaries, but were represented in the field as well. Several species, such as A. cuneata, A. pulverulenta, T. terricola, X. miniata, X. nemoralis, A. albimana, P. mirabilis, Ch. campestre, X. acerbus, Z. spinimana, P. festivus, D. praeficus and D. lutetianus could be proved only in the adjacent boundaries. Altogether positive effects on the dominance structure of spiders could be shown. An increasing biodiversity may be expected.     

Does individual internal state affect the presence of a barrier web in Argiope bruennichii (Araneae: Araneidae)?

A barrier web created by some orb-web spiders has a three-dimensional web structure made of nonsticky threads, which is believed to provide a defensive function against predators. To test for a possible antipredatory function, we investigated relationships between the presence of a barrier web and an individuals internal state in the orb-web spider Argiope bruennichii, which builds orb-webs with and without a barrier web. Hunger level and molting as measures of internal state were represented by relative abdominal width and relative web size, respectively. Field survey showed that individuals with a wider abdomen and a smaller web tended to construct a barrier web. The positive relationship between body width and the presence of a barrier web supports the hypothesis of an antipredatory function as well-fed individuals are likely to expend more effort for defense. The small web size, however, may not be representative of molting because a correlation existed between web size and potential web substrates; therefore, the effect of molting on the presence of barrier web remains unclear.     

Cues that Spiders (Araneae: Araneidae,Tetragnathidae) Use to Build Orbs: Lapses in Attention to One Set of Cues because of Dissonance with Others?

Even for small animals such as spiders, behavioral decisions are sometimes influenced by multiple cues. Orb webs constitute exquisitely precise records of the stimuli the spider experienced and the decisions that it made while building its web. In addition, because spiders appear to sense their webs largely by touch, direct behavioral observations can determine which stimuli they probably sense. Previous studies have shown that when an orb‐weaving spider decides how far apart to space successive sticky lines during orb construction, it responds to at least five different kinds of stimuli, all of which apparently use a cue from the web, the location of the previous, inner loop of sticky spiral (IL location), as a point of reference. Here we show that two additional cues from the web, which are related to the position of the temporary spiral (TS), also influence sticky spiral spacing. A combination of direct observations of spider movements, analyses of complete and partially complete webs, and responses to experimental modifications of the web of two species in different families, Micrathena duodecimspinosa (Araneidae) and Leucauge mariana (Tetragnathidae), indicate that both the TS‐IL distance itself and the short‐term memory of the change in TS‐IL distance compared with that on other recently encountered radii correlate with sticky spiral spacing. When the TS‐IL distance was large, the spiders apparently ceased to attend to other cues. Thus, even the relatively stereotyped behavior of orb construction includes variation that stems from attention‐like mental processes.     

One species or several? Discordant patterns of geographic variation between allozymes and mtDNA sequences among spiders in the genus Metepeira (Araneae: Araneidae)

Paradoxically, an allozyme study of Metepeira "spinipes" (sensu lato) demonstrated extensive gene flow among four populations whose members are nevertheless morphologically and behaviorally distinct. Initially, the authors tentatively concluded that the populations exhibited panmixis and suggested that local environmental effects accounted for the apparent morphological and behavioral differences. However, they later concluded that such differences were too great to be accounted for by the environment alone and that the four populations actually represented three different species. To confirm that the allozyme results were, in fact, artifactual, we reexamined the relationships among these populations by sequencing a portion of the 12S mtDNA ribosomal subunit. In contrast to the allozyme result, our results demonstrate good agreement between patterns of genetic and morphological/behavioral variation. We suggest (1) that the allozyme allele frequencies are homogenized by balancing selection, not gene flow as was previously concluded, and therefore (2) that this study provides another instance in which inferences about population structures from allozyme data are misleading.     

An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family)

The new spider genus and species Trogloraptor marchingtoni Griswold, Audisio & Ledford is described as the type of the new family Trogloraptoridae. The oblique membranous division of the basal segment of the anterior lateral spinnerets of Trogloraptor suggests that this haplogyne family is the sister group of the other Dysderoidea (Dysderidae, Oonopidae, Orsolobidae and Segestriidae). Trogloraptor is known only from caves and old growth forest understory in the Klamath-Siskiyou region of Oregon and California.