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Many orb-web weaving spiders add highly visible zigzagging silk "decorations" to their webs that are thought to function in prey attraction or predator avoidance. Despite the long history of studies on the form, frequency, and function of these structures, little attention has been paid to their mode of construction. Here, we report for the first time the sequence of construction of decorations by Argiope luzona (Walckenaer, 1841), a common species in the northern Philippines. A disc-shaped decoration built by a juvenile was laid as several continuous loops in a modified figure-eight pattern. The resulting asymmetric design is typical of many Argiope spp., hence suggesting that disc decorations are built similarly across the genus. In a full cruciate decoration of an adult female spider -- consisting of four diagonal arms arrayed around the web's hub -- each two-armed diagonal was laid down in turn, each arm being laid from its outermost portion inward, the lower arm first. The mode of construction of the cruciate device suggests that this type of decoration evolved by duplication and diagonalizing the single two-armed vertical decoration seen in presumptively less derived Argiope. [ABSTRACT FROM AUTHOR]

Female sperm storage organs in arthropods are used as taxonomic characters since it is assumed that they do not change after maturation. However, in the Golden Silk spider, Trichonephila clavipes, the shape and sclerotization of the spermathecae change with a mating event. Moreover, mating in T. clavipes consists of several hundred copulations, but the male transfers all sperm during the first insertion of each pedipalp. Given this puzzling mating behaviour, we hypothesize that multiple copulations serve purposes other than sperm transfer and uptake, such as further altering the morphology of the storage site and/or transferring substances other than sperm. We compared virgin female T. clavipes with females after two copulations, one for each spermatheca, and after ad‐libitum mating. Each treatment consisted of two sub‐treatments in which the state of the sperm storage organs was inspected after a short (1–3 days) or a long (11 days) time interval after the female's final moult. The size of the spermathecae increased twofold in all mating treatments compared to virgin females. The thickness of the spermathecal wall increased significantly with time in all treatments similarly. The spermathecal epithelium, which releases secretion into the lumen of the spermathecae, seems most active in virgin females during the time when mating would normally occur and turns less active after mating and with age. The spermathecae contain secretion produced by the female before mating; and after mating, sperm and another secretion transferred by the male. The numerous sperm‐less matings in the ad‐libitum treatment resulted in male secretion in the copulatory ducts of the female genitalia, likely impeding sperm transfer by subsequent males. Out study shows that female genitalia can change considerably after having reached maturity and suggests that sperm‐less matings evolved in the context of sperm competition. [ABSTRACT FROM AUTHOR]

The article titled "Diversity and Microhabitat Association of Spider Fauna in Manas National Park, Assam, India" explores the diversity of spider species in Manas National Park in northeast India. The study was conducted from September 2018 to August 2021 in different habitat types, including woodland, grassland, and riparian habitats. A total of 73 spider species belonging to 47 genera and 16 families were recorded, with the majority of species found in woodland habitats. The study highlights the importance of conservation efforts in the region due to the significant diversity of spider species in the park. [Extracted from the article]

Present study reports the orb-weaver spider Neoscona theisi (Walckenaer, 1841) from the Northern Western Ghats, India with its DNA barcode studies and a preliminary phylogenetic analysis. Although the species is taxonomically well established with wide range of distribution, DNA barcode with verifiable voucher specimen in a National Repositories are wanting. In the data driven era and metabarcoding, DNA barcode library with verifiable voucher specimens are crucial. In the present account taxonomic account of the species is revisited, along with DNA barcode and discussion are made on the utility of DNA barcodes and reference barcode library. [ABSTRACT FROM AUTHOR]

The tropical, dry deciduous forests of Chandrapur district provide a wide variety of natural ecosystems to the spider species, leading to spider diversity and abundance. Hence the spiders can be grouped into various ecological guilds, based on the foraging mode as orb weavers, space web builders, sheet web builders, ambushers, ground runners, foliage runners, stalkers etc. The present investigation, therefore, has an interdisciplinary approach that will undertake a comprehensive and holistic study of spider diversity along with the plant diversity. Well established sampling protocols for spider collections were adapted in different selected sampling plots from Chandrapur district. The present study reveals the occurrence of 21 different families, 57 genera and 90 species. Out of total spider species recorded, about 43% were found orb weaver, 17% stalker, 14% ground runner, 13% ambusher, 8% foliage runner, 3% space web builder and 2% were sheet web builder. Occurrence of high number of Araneids could be due to mixed vegetation of the forest which provides enough space to build web of different size and protection from their predators. The forest is dry deciduous and rich in shrubs as understory habitats resulting into more number of Salticides and Lycocides which are stalker in guild. Moderate numbers of Thomicides found in this region is due to availability of flowering plants with deep vegetation in forest area. [ABSTRACT FROM AUTHOR]

Spider webs, and in particular orb webs, are among the most iconic characteristics of spider biology. The evolution of, and developmental changes in, orb webs have been well studied, but we still have a limited understanding of allometric relations between the size of orb webs and spider body size. In this study, we investigate this relationship using measurements from 55 individuals of two common orb-weaving spider (Araneidae) species in South Wales, UK. We recorded body size using two methods: direct measurements with calipers, and estimations from photographs using ImageJ software. We found that these two methods give almost identical measurements, supporting the use of image-based size measurement in many situations where this is advantageous. We also found evidence for negative allometry of orb web size (relative to spider body length), such that larger spiders build proportionately smaller webs. This implies that the 'giant webs' in some orb-weaver species must be the result of a fundamental shift in the constraints or advantages which result in the allometric relationships described here. [ABSTRACT FROM AUTHOR]

Social wasps are commonly considered generalists in their feeding habits, but there are genera with little information regarding their diet, such as Mischocyttarus de Saussure, 1853 (Hymenoptera: Vespidae), the most species-rich wasp genus in the world. The objective of this study is to report Mischocyttarus rotundicollis (Cameron, 1912) (Hymenoptera: Vespidae) feeding on a spider in the southeastern region of Brazil, aiming to expand information about its feeding behavior. The record occurred occasionally on September 23, 2023, in the state of Minas Gerais, Brazil, in the ecotone region between the Atlantic Forest and the Cerrado. The feeding of a species from the Araneidae family occurred in its web, and the individual of M. rotundicollis used the tarsi of its legs to cling to the silk threads of the web, which could suggest a specialization for the exploitation of this food resource. Our record provides further information on the feeding behavior and diet of M. rotundicollis and presents the first information on spider feeding by this species. Further studies are suggested to evaluate this possible hypothesis of specialization of the genus for foraging in spider webs.

Online citizen science platforms can be crucial to the scientific and regulatory community, but inherent biases based on organism traits can influence the likelihood of a species being reported and accurately identified. We explored how traits of orb weaving spiders impact data in iNaturalist, using the invasive Jorō spider as a case study. This species is an outlier among orbweavers due to its large size and bright coloration, and was the most frequently reported species, with the most identifications and research-grade observations. It was also reported by less experienced users on average, highlighting its potential role as a gateway species into community science participation. This bias towards large, flashy orbweaver species suggests underrepresentation of smaller, drab species. Given the increasing importance of open access digital biodiversity records, we encourage researchers to engage more with the iNaturalist community and contribute their expertise in improving the data quality wherever possible.

Argiope lobata (Pallas, 1772) of family Araneidae is recorded from Jordan. Only one female specimen of this species was collected in September 1989 from Abdoun, Amman, Jordan. [ABSTRACT FROM AUTHOR]

Revisions and detailed studies on the cosmopolitan genus Araneus Clerck, 1757 are carrying out in different parts of the world. Light green garden spider, Araneus viridiventris Yaginuma, 1969 are known from China, Japan, and Taiwan. It is recorded from India for the first time. Redescription of female genitalia with detailed photographs are presented in this study. Known distribution of this species is also mapped. [ABSTRACT FROM AUTHOR]

Spiders are significant predators in terrestrial habitats, with the highest diversity found in tropical ecosystems, but it is also where they are studied least. In this study, we analyzed the effect of seasonality and three environmental variables (precipitation, evaporation, and temperature) in the orb-weaver composition, richness, abundance, dominance, and diversity. In addition, the species turnover between three localities with differences in the vegetation composition and maintenance in the Sierra de Huautla, Morelos, Mexico, were evaluated. The collection methods used included beating vegetation and direct searches conducted over seven hours during daylight, once per month, between April 2013 and March 2014. A total of 17 species from 14 genera were registered. With the records, we compiled the first species inventory of araneids for the three localities, adding eight new species records for the state of Morelos. The predominant species were Neoscona oaxacensis (Keyserling, 1864) and Trichonephila clavipes (Linnaeus, 1767), but over 50% of the species that we recorded corresponded to a single individual. The Araneid community changed between the dry and rainy seasons in all three localities, with each locality responding differently to changes in environmental variables, with most variables maintaining a long-term effect on the spider community. [ABSTRACT FROM AUTHOR]

Identifying the source population of alien species is important to assess the distribution and potential effects in the invaded area. The araneid spider Cyrtophora citricola is widely distributed in Europe, Asia, and Africa; however, in the last 26 years, it has been reported in several countries across the Americas. To date, the geographic origin of the populations established in the Americas remains unclear, but considering the successful colonization after its recent arrival, assessing climatic similarities between the invaded and native geographic ranges could be useful to address this question. In this study, we used a combination of Species Distribution Models and Ordination Methods to assess the climatic match between the invaded region (the Americas) and two potential origins (southern Africa and the Mediterranean) aiming to determine the more likely origin for the populations established in the Americas. We found that the American populations of C. citricola occupy sites with climatic conditions more similar to those occupied by southern African populations, than to those occupied by the Mediterranean populations. Therefore, our results suggest a southern African rather than a Mediterranean origin for the populations established in America. In addition, our results also show that populations in America are spreading into sites that differ in climate conditions from those occupied by native populations. Further studies assessing intrinsic (e.g., physiological tolerances, plasticity, behavior, reproduction) and extrinsic (physical barriers, predator release) factors could provide further information to disentangle the mechanisms behind the geographic and climatic niche expansion of this species. [ABSTRACT FROM AUTHOR]

This first-ever extensive review of the construction behaviour of orb webs, of webs secondarily derived from orbs, and of non-orbs shows that the evidence favouring monophyly over convergent evolution of orbs is stronger than previously appreciated. The two major orb-weaving groups, Uloboridae and Araneoidea, share 31 construction behaviour traits, 20 of which are likely to be both derived and to have feasible alternatives, making convergence an unlikely explanation. Convergence in two lineages seems unlikely, and convergence in five different lineages, as proposed in some recent molecular studies of phylogeny, is even less credible. A further set of seven shared responses in orb design to experimentally constrained spaces also supports orb monophyly. Finally, a 'control' case of confirmed convergence on similar 'pseudo-orbs' in a taxonomically distant group also supports this argument, as it shows a low frequency of behavioural similarities. I argue that the omission of behavioural data from recent molecular studies of orb web evolution represents a failure of the analytic techniques, not the data, and increases the risk of making mistakes. In general, phylogenetic studies that aim to understand the evolution of particular phenotypes can benefit from including careful study of the phenotypes themselves. [ABSTRACT FROM AUTHOR]

A survey conducted to reveal on the spider diversity in different areas in Kannur District, Kerala, indicated a total of 31 species belonging to 15 families. The families Salticidae and Araneidae showed maximum species diversity. The study revealed that the selected study areas have favorable microhabitats for the spider fauna. [ABSTRACT FROM AUTHOR]

In the preliminary study conducted to document the spider fauna in Vallakadavu range, Idukki district, Kerala, a total of 33 species of spiders belonging to 29 genera from 12 families were recorded. Among the 12 families recorded, Araneidae was the most predominant with orb web weavers. From the guild analysis, the recorded families were categorized into seven principle types of web patterns. The study extends the range of Poecilotheria striata Pocock, 1895 in the state to the east. [ABSTRACT FROM AUTHOR]

The aim of the present study was to analyze the diversity of spiders across various parts of the Thattekkad Bird Sanctuary, Kerala, a tropical, semi evergreen, low-land forest located between the tributaries of the Periyar river. Survey of the spider fauna was carried out for a period of twelve months. In total, 3286 individuals were collected from the sanctuary, which consist of 89 species of spiders under 59 genera and 18 families. Araneidae was the most abundant family. The most abundant species was Hippasa agelenoides of Lycosidae family. Spiders belonging to six feeding guilds, i.e., orb - web weavers, stalkers, ground runners, scattered line weaver foliage runners and ambushers were identified. Relative abundances of spider community strongly differed with the pre-monsoon, monsoon and post monsoon seasons. Diversity indices - Margalef richness index, Pielou's evenness index, Shannon-Wiener and Simpson index were calculated. [ABSTRACT FROM AUTHOR]

Female specimens of the banded garden spider, Argiope trifasciata (Forskål, 1775), are reported for the first time from Iraq, based on material collected from three provinces of southern and middle Iraq. This record represents the sixth species of the Orb-weaver spiders for the Iraqi spider fauna. The characteristic features of this species are described and figured. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) is an increasingly pervasive pollutant that alters animal behaviour and physiology, with cascading impacts on development and survival. Recent evidence links exposure to ALAN with neural damage, potentially due to its action on melatonin synthesis, a powerful antioxidant. However, these data are scarce and taxonomically limited. Here, we used micro-CT to test the effects of short-term ALAN exposure on brain volumes in the Australian garden orb-weaving spider ( Hortophora biapicata ), a species commonly found in urban areas and, specifically, around street lights. We found that short-term ALAN exposure was linked to reductions in the volumes of brain structures in the primary eye visual pathway, potentially as a consequence of oxidative stress or plastic shifts in neural investment. Although the effects of ALAN were subtle, they provided new insights into potential mechanisms underpinning the behavioural and physiological impacts of ALAN in this important urban predator.

Differences between sexes in growth, ecology and behaviour strongly shape species biology. In some animal groups, such as spiders, it is difficult or impossible to identify the sex of juveniles based on external morphology. This information would be useful for field surveys, behavioural experiments and ecological studies, such as those on sex ratios and dispersal. In species with sex chromosomes, sex can be determined based on the specific sex chromosome complement. Additionally, information on the sequence of sex chromosomes provides the basis for studying sex chromosome evolution. We combined cytogenetic and genomic data to identify the sex chromosomes in the sexually dimorphic spider Argiope bruennichi and designed quantitative real-time polymerase chain reaction sex markers. We found that the genome size and GC content of this spider fall into the ranges reported for the majority of araneids. The male karyotype is formed by 24 acrocentric chromosomes with an X1X20 sex chromosome system, with little similarity between X chromosomes, suggesting an origin of these chromosomes by X chromosome fission or early duplication of an X chromosome and subsequent independent differentiation of the copies. Our data suggest X chromosomes of similar sizes in A. bruennichi. They are smaller chromosomes of the complement. Our findings open the door to new directions in spider evolutionary and ecological research. [ABSTRACT FROM AUTHOR]

The present investigations were carried out to elucidate the spider fauna of the Sagar district of Madhya Pradesh. A total of 1,505 spider specimens were documented from various sites of the study area. A total of 74 species grouped under 58 genera and 22 families are reported. The family Araneidae was the most common, accounting for 31й of the overall population followed by Salticidae, which accounted for 15й of the overall population. Spiders belonging to seven guild structures were identified which were then classified on the basis of their dietary habits. Further research is needed to analyze the behavior, biology and web patterns of these ubiquitous creatures. [ABSTRACT FROM AUTHOR]

Spiders are significant predators in terrestrial habitats, with the highest diversity found in tropical ecosystems, but it is also where they are studied least. In this study, we analyzed the effect of seasonality and three environmental variables (precipitation, evaporation, and temperature) in the orb-weaver composition, richness, abundance, dominance, and diversity. In addition, the species turnover between three localities with differences in the vegetation composition and maintenance in the Sierra de Huautla, Morelos, Mexico, were evaluated. The collection methods used included beating vegetation and direct searches conducted over seven hours during daylight, once per month, between April 2013 and March 2014. A total of 17 species from 14 genera were registered. With the records, we compiled the first species inventory of araneids for the three localities, adding eight new species records for the state of Morelos. The predominant species were Neoscona oaxacensis (Keyserling, 1864) and Trichonephila clavipes (Linnaeus, 1767), but over 50% of the species that we recorded corresponded to a single individual. The Araneid community changed between the dry and rainy seasons in all three localities, with each locality responding differently to changes in environmental variables, with most variables maintaining a long-term effect on the spider community.

Spiders prevalent in cattle sheds were observed predating on adult Culicoides sp. Even juveniles of Neoscona mukerjei (Tikader 1980) predated on small insects which included blood engorged Culicoides oxystoma; whereas adults preferred larger one. Adults and juveniles of Menemerus bivittatus (Dufour 1831) and juveniles of Marpissa sp. also feed on engorged adults which were identified as C. peregrinus (Kieffer 1910) and C. oxystoma (Kieffer 1910) collected within the animal sheds. Predations on Culicoides midges by M. bivittatus in field condition were supplemented by gut content analysis using Culicoides sp. specific primer pairs. Diet analysis of M. bivittatus (both sexes) diet collected from two different sheds demonstrated the presence of biting midges as one of the prey. Laboratory experiments on time intervals for prey choice decision by M. bivittatus depicted inter-individual differences, however, no variation was observed in prey selection (different age groups of midges). [ABSTRACT FROM AUTHOR]

Trichonephila clavipes (Linnaeus, 1767) is known as a golden silk orb-weaver and belongs to the family Araneidae. T. clavipes is one of the few spider species whose genome has been reported and model organism for a molecular biology. Here, we present the complete mitochondrial genome sequence (mtDNA) of T. clavipes. The sequence was obtained using a long-read Nanopore technology and corrected with an Illumina technology. The circular genome is 14,902 bp in length, and the AT content was 77.21%. The T. clavipes mitochondrial genome contains 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes. The majority of PCGs were found on the heavy strain.

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Understanding the full diet of natural enemies is necessary for evaluating their role as biocontrol agents, because many enemy species do not only feed on pests but also on other natural enemies. Such intraguild predation can compromise pest control if the consumed enemies are actually better for pest control than their predators. In this study, we used gut metabarcoding to quantify diets of all common arachnid species in Swedish and Spanish apple orchards. For this purpose, we designed new primers that reduce amplification of arachnid predators while retaining high amplification of all prey groups. Results suggest that most arachnids consume a large range of putative pest species on apple but also a high proportion of other natural enemies, where the latter constitute almost a third of all prey sequences. Intraguild predation also varied between regions, with a larger content of heteropteran bugs in arachnid guts from Spanish orchards, but not between orchard types. There was also a tendency for cursorial spiders to have more intraguild prey in the gut than web spiders. Two groups that may be overlooked as important biocontrol agents in apple orchards seem to be theridiid web spiders and opilionids, where the latter had several small-bodied pest species in the gut. These results thus provide important guidance for what arachnid groups should be targets of management actions, even though additional information is needed to quantify all direct and indirect interactions occurring in the complex arthropod food webs in fruit orchards. [ABSTRACT FROM AUTHOR]

Background. The use of Arthropodae toxins for electrophysiological experiments is very important, but experimental data in this regard are scarce. The aim of this study was to obtain experimental data about the influence of Nephila clavata spider venom and its main active component – toxin JSTX-3 on the glutamate channel-receptor complex. Methods. Kainate was used as agonist of glutamate channel-receptor complex because it initiated non-inactivated transmembrane electric currents in rat hippocampal membranes in electrophysiological experiments were used for the study. All chemicals were applied to perfused hippocampal pyramidal neuronal membranes using ’concentration-clamp’ technique and voltage-clamp recording. Results and discussion. The studied substances – integral venom and toxin JSTX-3 – demonstrated the properties of glutamate channel-receptor complex antagonists. The amplitudes of electric transmembrane currents activated by glutamate, kaina­te, and quisqualate decreased (sometimes to zero) after the application of glutamate channel-receptor complex antagonists to the rat hippocampal membrane under the voltage-clamp conditions. The kinetics of activation and desensitization (in case of glutamate and quisqualate) of transmembrane electric currents were not affected by these antagonists. The effects of Nephila clavata integral venom were studied the in concentrations of 10-8–10-4 units/µL, the effects of JSTX-3 – in the concentrations of 10-6–10-5 mol/L. Integral venom did not block the studied currents completely, but it reduced their amplitudes to a certain level. Integral venom blocked glutamate-activated currents up to 36±15 % of the initial values, kainate-activated – up to 34±16 %. In contrast, JSTX-3 almost completely blocked ion currents activated by these agonists at the holding potential of -100 mV: the amplitudes of kainate-activated currents under the action of this blocker decreased to 6±3 % of the initial values. Integral venom blocking effects were irreversible in contrast to partially reversible JSTX-3 action. The differences between antagonists were also revealed in the quantitative characteristics of blocking action. The following effects were studied under the antagonists’ influence: the degree of currents suppression and their removal by “washing”, “dose–effect” dependency, the antagonists’ influence on activated and inactivated receptors; kinetics of the antagonists’ action and removal, dissociation constants for blockers with reversible action. Conclusions about the mechanisms of the antagonists’ influence on the glutamate channel-receptor complex, the physiological role of integral venom and JSTX-3 as well as comparison of the caused effects were made. The influence of Aspergillus oryzae proteases pretreatment during hippocampal neurons preparation for experiments, and the creation of a physical model of the molecular system “glutamate channel-receptor complex – glutamate – antagonist – proteases” are discussed.

The purpose of this study was to present experimental data on the action of venom and toxins from Argiope lobata spiders on the glutamate channel-receptor complex. Kainate was used as a glutamate channel-receptor complex agonist because it initiated non-inactivated inward ionic transmembrane electric currents in rat hippocampal membranes. Effects of antagonists can be studied on the background of such currents. Chemo-activated currents and glutamate channel-receptor complex antagonists from A. lobata were studied. Electrophysiological experiments were performed and all chemicals were applied to perfused hippocampal pyramidal neuronal membranes using the ’concentration-clamp’ technique. A conventional electronic circuit was used for single-electrode voltage-clamp recording. All substances under study – integral venom, argiopin, argiopinine 1, argiopinine 2 – demonstrated similar properties. The amplitudes of ionic currents activated by glutamate, kainate and quisqualate decreased after the application of these antagonists to the rat hippocampal membrane under the voltage-clamp conditions. The kinetics of currents’ activation and desensitization (in case of glutamate and quisqualate) were not affected by the antagonists. The effects of argiopin and integral venom were investigated within the concentrations of 5.10-8–1.10-2 mol/L and 10-4 g/mL, respectively. At these concentrations, neither integral venom, nor argiopin suppressed glutamate-, kainate-, quisqualate-activated currents completely. The amplitude of non-blocked integral venom components averaged 14.4% of the original value for kainate-activated currents. Argiopin reduced the amplitudes of kainate-activated currents to 19% of the control values. Argiopinine 1 and argiopinine 2 acted in a very similar way. Both substances caused reducing of glutamate- and kainate-activated ion currents amplitudes acting in small quantities of 10-5–10-6 mol/L. The differences between them were in the quantitative characteristics of the blocking action. Such effects as “dose–effect” dependency, the antagonists’ influences on activated and inactivated receptor; kinetics of the antagonists’ action and their removal, analysis of dissociation constants were studied under the antagonists’ influence. Conclusions about the mechanisms of the antagonists’ influence on glutamate channel-receptor complex, as well as a comparison of the caused effects were made.

Indian sandalwood Santalum album L. plantations in Karnataka were surveyed to study the diversity and abundance of spider fauna. A total of 1,244 individuals belonging to 56 spider species in 40 genera under 14 families were recorded in the sandalwood plantations. Among the spider families recorded, Araneidae was the most dominant with 15 species in nine genera followed by Salticidae with 13 species in 10 genera, Thomisidae with seven species in four genera, Oxyopidae with four species in three genera, Uloboridae with four species in a genus, and Theridiidae by three species each under three genera. Lycosidae and Sparassidae are represented by two species under two genera each. The families Cheiracanthiidae, Clubionidae, Hersiliidae, Philodromidae, and Pholcidae are represented by a species each. The pruning of sandalwood revealed a significant negative effect on the occurrence and distribution of spiders. [ABSTRACT FROM AUTHOR]

In the present study, an effort has been made to elucidate the gut bacterial diversity of twelve species of the family Araneidae under three subfamilies collected from 5 states of India along with their predicted metabolic role in functional metabolism. Further, we also compared the host species phylogeny based on partial cytochrome c oxidase subunit I (COI) sequences with the gut bacteria composition dendrogram to decipher the phylosymbiotic relationships. Analysis revealed the presence of 22 bacterial phyla, 145 families, and 364 genera in the gut, with Proteobacteria, Firmicutes, Actinobacteria, and Deinococcus-Thermus as the highest abundant phyla. Moreover, phylum Bacteriodetes was dominated only in Cyclosa mulmeinensis and Chlamydiae in Neoscona bengalensis. At the genus level, Bacillus , Acinetobacter , Cutibacterium , Pseudomonas , and Staphylococcus were the most dominant genera. Furthermore, the genus Prevotella was observed only in Cyclosa mulmeinensis, and endosymbiont Wolbachia only in Eriovixia laglaizei. The differential abundance analysis (DeSeq2) revealed the 19 significant ASVs represented by the genera like Acinetobacter , Vagoccoccus , Prevotella , Staphylococcus , Curvibacter , Corynebacterium , Paracoccus , Streptococcus , Microbacterium , and Pseudocitrobacter. The inter- and intra-subfamilies comparison based on diversity indices (alpha and beta diversity) revealed that the subfamily Araneinae have high richness and diversity than Argiopinae and Gasteracanthinae. The phylosymbiotic analysis revealed that there is no congruence between the gut bacteria composition dendrogram with their host phylogeny. [ABSTRACT FROM AUTHOR]

Abstract The present research was carried out to explore the spider fauna of Buner valley with taxonomic study from February 2018 to January 2019. For this purpose samples were collected, four times at each month from 4 tehsils: Daggar, Gagra, Mandan and Totalai. Two methods were used, hand picking and sweep net for collection of samples. During day and night, three habitats, arid area, agriculture land and building area were search for collection. A total of 534 samples of spider were collected from four sampling sites, in which 379 were belonging to family Araniedae. After confirmation, the identified species were belonging to 8 genera (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia and Poltys) and 19 species. 18 of them were identified to specie level while a single specie to its generic level. The genus Neoscona was the dominant genus 26.31% having 5 species while the genus Argiope 21.05% is the second dominant having 4 species followed by Cyclosa 15.78% having 3 species followed by Cyrtophora and Araneus 10.52% having two species both. The Poltys and Larinia 5.26% are the rarest genera represent single-single specie both. Statistical analysis show that specie richness (D) = 5.77, Simpson index (1-D) = 0.87, Shannon index (H) = 2.33. Diversity of spiders was evenly distributed and calculated Evenness value was H/InS = 0.5408. There is also few atypical species and Fisher alpha estimate high value (Fisher α) = 4.42. Chao-1 estimated we have reported 22 species.

Tropical dry forest is one of the most threatened and least studied tropical ecosystems despite high species diversity and endemism. In Colombia, the knowledge of spider diversity in this ecosystem is limited. Herein, we compare the diversity and species composition of orb-weaving spiders in a primary and a secondary tropical dry forest in northern Colombia. Sampling was conducted in March and May 2018 using aerial and ground hand collection methods. We collected 1106 specimens belonging to seven families and 76 species. The species Aculepeira travassosi (Soares and Camargo, 1948), Ariston aristus Opell, 1979, Eriophora nephiloides (O. Pickard-Cambridge, 1889), Eustala conformans Chamberlin, 1925, Eustala guttata F.O. Pickard-Cambridge, 1904, Eustala illicita (O. Pickard-Cambridge, 1889), Micrepeira hoeferi Levi, 1995, Testudinaria quadripunctata Taczanowski, 1879, Tetragnatha elongata Walckenaer, 1841, Tetragnatha mandibulata Walckenaer, 1841 and Verrucosa reticulata (O. Pickard-Cambridge, 1889) are recorded from Colombia for the first time. Spider diversity was significantly different among forests, and the similarity in species composition was 43%. Diversity was only 26% lower in the secondary tropical dry forest, demonstrating the importance of this type of forest as reservoirs of spider diversity. [ABSTRACT FROM AUTHOR]

Orb web spiders, a familiar feature of terrestrial ecosystems, are much admired for their intricate spiral wheel-shaped webs. Maharashtra is a State occupying the Central and Western regions of India. A checklist of the orb web spiders of Maharashtra has been prepared, which consists of 73 species in 24 genera of two families, Araneidae and Tetragnathidae. Of these, 61 species in 19 genera belong to family Araneidae and 12 species in 5 genera belong to family Tetragnathidae. [ABSTRACT FROM AUTHOR]

The checklist of spiders of Rajasthan State in India is provided here, which is represented by 71 species of spiders included under 47 genera of 15 families. The most species-rich families reported so far are Araneidae and Gnaphosidae with 14 species each, followed by Lycosidae with 12 species. Studies done on the spider fauna of Rajasthan State till date is reviewed.

The following eight new synonyms are proposed: Araneus arganicola Simon, 1909 = Neoscona subfusca (C. L. Koch, 1837) syn. nov.; Drassus nugatorius Karsch, 1881 = Odontodrassus mundulus (O. Pickard-Cambridge, 1881) syn. nov.; Drassus sockniensis Karsch, 1881 = Poecilochroa pugnax (O. Pickard-Cambridge, 1874) syn. nov.; Drassus tarrhunensis Karsch, 1881 = Megamyrmaekion caudatum Reuss, 1834 syn. nov.; Prosthesima kerimi Pavesi, 1880 = Zelotes tragicus (O. Pickard-Cambridge, 1872) syn. nov.; Prosthesima quadridentata Strand, 1906 = Scotophaeus quadridentatus Caporiacco, 1928 = Setaphis mollis (O. Pickard-Cambridge, 1874) syn. nov.; Steatoda erigoniformis (O. Pickard-Cambridge, 1872) = Euryopis albomaculata Denis, 1951 syn. nov. The position of Drassus obscurus Lucas, 1846 in Drassodes is confirmed and the first figures of the female epigyne and vulva are given. The citation of Dactylopisthes digiticeps (Simon, 1881) from Tunisia by Pavesi (1884) is a misidentification and concerns Thaumatoncus indicator Simon, 1884. A new species is described: Pelecopsis pavesii spec. nov. from Tunisia, erroneously identified by Pavesi (1884) as Pelecopsis parumpunctata (Simon, 1881). [ABSTRACT FROM AUTHOR]

Successful biological invasions are characterized by the spread of a population across a landscape. Range expansion conditions can favour different phenotypes at the leading edges of the range compared to those at the core. Although Cyrtophora citricola is a non-native spider species that was documented in Florida, U.S.A. almost two decades ago, the status of its populations remains unstudied. We report two populations that have spread northward along both eastern and western coasts from a putative common origin. We asked whether the leading edges of these two range expansions are composed of different personality types compared to the original core and whether core-to-edge patterns in personality are consistent between the two replicate populations. More voracious, more exploratory and bolder spiders were predicted to occupy the leading edge, because these personality types are assumed to be associated with dispersive, successful colonizers in novel environments. While leading-edge spiders were indeed faster to respond and attack prey stimuli and active longer in novel environments compared to spiders from the core, the two populations diverged in boldness. On average, western spiders were less bold and exploratory towards newer colonization sites, whereas eastern spiders were bolder at newer sites. The divergence in exploratory behaviour and boldness between these populations highlights the difficulties in generalizing how traits may become assorted across an expanding range and stress the importance of using replicate populations when possible. These results suggest that range level processes can be inconsistent and highlight the importance of investigating how the strength of local adaptation may swamp processes such as spatial sorting. • Cyrtophora citricola has expanded ∼240 km north in ∼20 years from southern Florida. • Two urban populations have putatively branched along both coasts from a common origin. • Leading-edge spiders differed on average from those at the southern core. • Spiders at both northern fronts were more responsive and voracious towards prey. • Western and eastern spiders diverged in patterns of exploration and boldness. [ABSTRACT FROM AUTHOR]

To capture prey, orb-web spiders create complex traps whose efficiency is contingent on a variety of factors that are not yet completely understood, including web size, competition for food, sun exposure, presence of web decorations and web orientation. Here we evaluate such factors in the field and ask which of them are the most influential variables affecting the quantity of prey captured in Argiope argentata webs. Webs were observed during the morning and the number of prey attached to each web was counted. Using the approach of information criteria based on the Akaike information criterion (AIC) values of each candidate model, we averaged the parameters of a global model, finding that the only predictor which 95% confidence interval did not include zero, was exposure to sunlight (whether the web is continuously shaded or continuously exposed to sunlight). All other variables did not explain variation in prey capture. We conclude that only sun exposure has an important effect on orb-web spiders' prey capture efficiency in A. argentata. We additionally argue that silk decorations have different functions depending on the habitat and the species. [ABSTRACT FROM AUTHOR]

Silk production is a prominent characteristic of spiders. The silk is extruded through spigots located on the spinnerets, which are single- to multimembered paired appendages at the end of the abdomen. Most extant spiders have three pairs of spinnerets, and in between either a cribellum (spinning plate) or a colulus (defunct vestigial organ), dividing these spiders into cribellate and ecribellate species. Previous research has shown that cribellate and ecribellate spiders differ not only in the composition of their spinning apparatus but also in the movements of their spinnerets during silk spinning. The objective of this study was to determine whether the differences in spinneret movements are solely due to variations in spinneret shape or whether they are based on differences in muscular anatomy. This was accomplished by analyzing microcomputed tomography scans of the posterior abdomen of each three cribellate and ecribellate species. It was found that the number of muscles did not generally differ between cribellate and ecribellate species, but varied considerably between the species within each of these two groups. Muscle thickness, particularly of the posterior median spinneret, varied slightly between groups, with cribellate spiders exhibiting more robust muscles, possibly to aid in the combing process during cribellar thread production. Interestingly, the vestigial colulus still possesses muscles, that can be homologized with those of the cribellum. This exploration into spinneret anatomy using microcomputed tomography data reveals that despite being small appendages, the spider spinnerets are equipped with a complex musculature that enables them to perform fine-scaled maneuvers to construct different fiber-based materials., (© 2024 The Authors. Journal of Morphology published by Wiley Periodicals LLC.)

Conspicuous colours in animals are usually explained by mate attraction, predator avoidance and prey attraction. Predators may lure prey by mimicking food or other resources. Alternatively, some animals avoid predation by visually signalling unpalatability to predators. The evolution of a signal is affected by receiver processing mechanisms. Therefore, variation in sensory systems may explain the evolution of colour polymorphism of conspicuous species. We aimed to investigate the role of receivers in the evolution and maintenance of colour conspicuousness and polymorphism in Gasteracantha cancriformis (Araneidae). We tested two hypotheses: (1) conspicuous coloration is a prey lure strategy; (2) conspicuous coloration is a warning signal to predators. Furthermore, we identified the taxonomic order of prey captured and the type of predator (avian versus arthropod). To assess the role of prey, we conducted a field experiment in which webs were assigned to one of four treatments: yellow, red or black spider models, or no model. For each treatment, we counted the number of prey trapped on the webs and calculated the damaged area of the webs. To assess the role of predators, we conducted a second field experiment in which we attached yellow, red and black models to trees using nylon thread and observed the number of attack markings on each model. Our results did not corroborate the prey attraction hypothesis. In the predation experiment, black models had more attack markings, indicating that yellow and red models were less preferred. This suggests that spider coloration may play a role in predator avoidance. Colour polymorphism in this species is possibly a multifunctional attribute, where some morphs benefit from aposematism, whereas others may have alternative fitness advantages. Nonadaptive explanations should also be considered in future experiments of the evolution and maintenance of colour polymorphisms. • We tested whether orb-web spider colour morphs attract prey or deter predators. • There was no difference in foraging success of models (red, yellow, black, none). • Black models bore more attack marks than red and yellow models. • Conspicuous coloration is possibly a warning signal in G. cancriformis. [ABSTRACT FROM AUTHOR]

Se hace referencia a la primera observación de Neoscona byzanthina (Pavesi, 1876) (Araneae, Araneidae) de la Península Ibérica. El ejemplar fue capturado en octubre de 2018 en un encinar adehesado (Extremadura, España).

The purpose of the work was the examination of various databases construction as well as examination of possible errors. Peculiarities of biological objects which should be taken into account during databases design were analyzed. The methods for electronic collections with databases of biological organisms elaboration were studied. The appropriate algorithms for environmental conservation were analyzed and compared with some foreign analogs in order to study positive and negative experiences. The requirements for database with information about Noctuidae (Lepidoptera) and some Areneidae were formulated for the development of electronic information system “EcoIS”. The description of developed relational database with information about insects with analysis of selected object area were suggested taking into concideration the characteristics of biological objects and characteristics of information systems analogues. Conclusions concerning described new means with bioobjects databases and their application on the example of “EcoIS” system were done as well as some recommendations for the construction of databases with the information about living organisms basing on our experience.

An exhaustive study was conducted to document spider fauna in cashew orchards of the Cashew Research Station, Madakkathara, Kerala, India from January 2015 to July 2017. A total of 63 species of spiders under 52 genera belonging to 14 families were recorded. The most species-rich families were Salticidae and Araneidae representing 33 and 27 per cent, respectively, of the total spider fauna. A guild structure analysis revealed six feeding guilds, viz.: stalkers, orb-web builders, foliage runners, scattered line weavers, ground runners, and ambushers. The occurrence of spiders was at a maximum during the monsoon with 59 species, followed by 26 during winter, 16 species during summer, and eight species being present all-round the year. [ABSTRACT FROM AUTHOR]

Studies relating to spiders in Gujarat have been sporadic and most of the spider documentation have been done from agriculture fields, wetlands and few from protected areas. One such undocumented area was Jambughoda Wildlife Sanctuary, Panchmahal District, Gujarat. Therefore, a study to document the spider diversity was carried out in Jambughoda Wildlife Sanctuary from July 2012 to October 2015. A combination of four sampling methods namely, belt transect along with hand-pick method, pitfall sampling, vegetation beating and leaf litter extraction were used for collection of spiders from different strata. During the study, a total of 138 species belonging to 90 genera and 29 families were recorded from the study area. Of which, 21 species and 17 genera were recorded for the first time from Gujarat State. The theridiid genus Cephalobares O. Pickard-Cambridge, 1870 was recorded for the first time from India. The families Araneidae, Salticidae, Theridiidae and Oxyopidae were found to be dominant in the area. We recognized seven feeding guilds namely ambushers, foliage runners, ground runners, orb weavers, sheet web-builders, space web-builders and stalkers. Amongst these, orb-weavers, stalkers and ground runners were dominant. This documentation, however, forms the baseline information for spiders of Jambughoda WLS, suggesting the great diversity of the spider fauna in this protected area, which can be further explored. [ABSTRACT FROM AUTHOR]

Sexual reproduction is pervasive in animals and has led to the evolution of sexual dimorphism. In most animals, males and females show marked differences in primary and secondary sexual traits. The formation of sex-specific organs and eventually sex-specific behaviors is defined during the development of an organism. Sex determination processes have been extensively studied in a few well-established model organisms. While some key molecular regulators are conserved across animals, the initiation of sex determination is highly diverse. To reveal the mechanisms underlying the development of sexual dimorphism and to identify the evolutionary forces driving the evolution of different sexes, sex determination mechanisms must thus be studied in detail in many different animal species beyond the typical model systems. In this perspective article, we argue that spiders represent an excellent group of animals in which to study sex determination mechanisms. We show that spiders are sexually dimorphic in various morphological, behavioral, and life history traits. The availability of an increasing number of genomic and transcriptomic resources and functional tools provides a great starting point to scrutinize the extensive sexual dimorphism present in spiders on a mechanistic level. We provide an overview of the current knowledge of sex determination in spiders and propose approaches to reveal the molecular and genetic underpinnings of sexual dimorphism in these exciting animals. [ABSTRACT FROM AUTHOR]

We address some of the taxonomic and classification changes proposed by Kuntner et al. (2019) in a comparative study on the evolution of sexual size dimorphism in nephiline spiders. Their proposal to recircumscribe araneids and to rank the subfamily Nephilinae as a family is fundamentally flawed as it renders the family Araneidae paraphyletic. We discuss the importance of monophyly, outgroup selection, and taxon sampling, the subjectivity of ranks, and the implications of the age of origin criterion to assign categorical ranks in biological classifications. We explore the outcome of applying the approach of Kuntner et al. (2019) to the classification of spiders with emphasis on the ecribellate orb-weavers (Araneoidea) using a recently published dated phylogeny. We discuss the implications of including the putative sister group of Nephilinae (the sexually dimorphic genus Paraplectanoides) and the putative sister group of Araneidae (the miniature, monomorphic family Theridiosomatidae). We propose continuation of the phylogenetic classification put forth by Dimitrov et al. (2017) , and we formally rank Nephilinae and Phonognathinae as subfamilies of Araneidae. Our classification better reflects the understanding of the phylogenetic placement and evolutionary history of nephilines and phonognathines while maintaining the diagnosability of Nephilinae. It also fulfills the fundamental requirement that taxa must be monophyletic, and thus avoids the paraphyly of Araneidae implied by Kuntner et al. (2019). [ABSTRACT FROM AUTHOR]

Protandry occurs when males mature prior to females in the breeding season. There may be a fitness benefit for males if they are able to copulate and defend virgin and more fecund females. Therefore, fitness benefits can be investigated by studying assortative mating during mate guarding of virgin females before and after female sexual maturation. The asynchrony of female development in the protandrous spider Manogea porracea (Araneidae) provides an opportunity to investigate how female sexual maturity (subadult and adult females) influence size-assortative pairing. We investigated size differences between couples composed of males and subadult females, and of males and adult females. We hypothesized that size-assortative pairing is stronger in couples with adult females. Adult females were larger than subadults, but the size of males paired with females from both groups was similar. We found assortative pairing within all couples involving an adult female. However, this pattern was not observed among couples with subadult females. It is possible that the production of sexual pheromones by adult females after their last molt intensifies male intrasexual competition, promoting positive assortative pairing. We discuss the potential mechanisms affecting male mate choice and mate competition during pairings in M. porracea. [ABSTRACT FROM AUTHOR]

• The tissues of A. bruennichi host tremendously diverse assemblages of bacteria. • Wolbachia and Rickettsia were more abundant in spiders fed a lipid-rich diet. • Higher OTU richness of endosymbionts was associated with more locomotion. • Tissue-resident microbes were dominated by Firmicutes. • Hosts fed the standard diet had the highest α diversity of tissue-resident microbes. The ability to spread and build quality webs is crucial to spider survival. These abilities may differ in response to dietary adjustments and changes in assemblages of tissue-resident bacteria, including vertically transmitted endosymbiotic taxa, particularly when expanding outside the native ranges. We measured the physical and behavioral parameters of the invasive wasp spider Argiope bruennichi subjected to four types of diets, including protein-rich and lipid-rich diets. We used 16S rDNA sequencing to evaluate vertically and horizontally transmitted tissue-resident bacteria, including endosymbionts, in the cephalothorax and legs of the tested spiders. The diet composition affected the body weight and carapace length as well as the locomotor parameters but not the orb-weaving abilities. Dietary treatments led to changes in the diversity and operational taxonomic unit (OTU) richness of facultative and obligate tissue endosymbionts, with Wolbachia and Rickettsia having higher relative abundance in spiders fed a lipid-rich diet. The higher OTU richness of facultative and obligate endosymbionts was associated with better locomotor performance. The other tissue-resident microbes were dominated by Firmicutes; the dominance and diversity of tissue-resident microbiomes also differed among spiders treated with different diets. The highest alpha diversity of tissue-resident microbes was present in spiders fed the standard diet, whereas all other diets led to a decrease in alpha diversity and various changes at the level of individual genera and OTUs. In conclusion, the tissues of A. bruennichi host tremendously diverse assemblages of bacteria, including obligate or facultative endosymbionts, which are sensitive to differences in diet composition and affect the locomotion of their hosts. [ABSTRACT FROM AUTHOR]