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The thread-legged assassin bug Gardena melinarthrum Dohrn, 1860 (Heteroptera: Reduviidae) is reported for the first time from Thailand. Morphological data of the female adult, including detailed information of the genitalia, is provided with photographs. We also report the predation of an araneophagic spider Portia sp. (Araneae: Salticidae) by the bug in a spider’s web. It is the occasional observation of intra-guild predation evidence involving an assassin bug (Hemiptera: Reduviidae: Gardena melinarthrum) and a spider (Araneae: Salticidae: Portia sp.) in a riparian habitat.

Parasitoids are significant ecological elements of terrestrial food webs and have evolved within seven insect orders. Interestingly, however, associations with spiders as hosts have evolved only in two insect orders, Diptera and Hymenoptera. Here, we summarize various aspects of host utilization by dipteran flies with an emphasis on associations with spiders. Our synthesis reveals that spider flies (family Acroceridae) have evolved a unique life strategy among all the parasitoid taxa associated with spiders, in which koinobiont small-headed flies utilize an indirect oviposition strategy. This indirect oviposition in spider flies is inherited from Nemestrinimorpha ancestors which appeared in the Late Triassic and is characterized by the evolution of planidial larvae. Further, we discuss the advantages and disadvantages of indirect oviposition in spider flies. On the one hand, indirect oviposition allows the fly to avoid contact/wrestling with spider hosts. On the other hand, larval survival is low because the planidium must actively seek out and infect a suitable host individually. The risk of failure to find a suitable spider host is offset by the fly's extremely high fecundity. [ABSTRACT FROM AUTHOR]

Spiders are among the most diversified and abundant predators in terrestrial ecosystems across the world, but information on their prey is limited. Particularly, there is paucity of data for prey-specialised species, such as palpimanid spiders. Here we investigated the trophic strategy of four palpimanid species (Diaphorocellus biplagiatus, Otiothops birabeni, Palpimanus gibbulus, and P. potteri) representing all three subfamilies (Chediminae, Otiothopinae, Palpimaninae) and three geographic areas (Mediterranean, South America, South Africa) in order to infer a trophic strategy for the entire family Palpimanidae. We predicted that all palpimanids are specialised araneophagous predators. We used molecular gut-content analysis, combined with comparative analysis of morphological trophic traits. We found all four species to catch spiders more than insects. All species captured spiders belonging to several families, but predominantly those of the cursorial guild. The diet composition did not differ between sexes and juveniles. The breadth of trophic niche was narrow for all species, suggesting stenophagy. Using comparative analysis of morphological traits (thick cuticle, stout forelegs, scopulae on forelegs, and stridulatory apparatus) and araneophagy, we estimated that preying on spiders combined with the morphological traits is ancestral state for the entire family. We suggest that the whole family Palpimanidae includes araneophagous species. [ABSTRACT FROM AUTHOR]

Previous research on Cyrba algerina (Araneae, Salticidae) has shown this jumping spider expresses predatory specialisation with respect to spiders as prey as well as inter-population variation in responsiveness to prey-spider odour. However, this earlier research pertained to a single prey species (Oecobius machadoi) and only field-collected C. algerina individuals were tested. Here we extend the previous research by using laboratory-reared, as well as field-collected, individuals of C. algerina and also by using another prey-spider species, Zelotes thorelli, as well as O. machadoi. Two localities in Portugal are considered, Sintra where C. algerina and both prey species are abundant and Tavira where C. algerina is present but neither prey species has been found. In olfactometer experiments, field-collected C. algerina individuals from Sintra, but not Tavira, were attracted to the odour of both prey species. Next, we tested the response of laboratory-reared Sintra C. algerina individuals that had been maintained with no prior experience with the odour of either prey species. We found no evidence of laboratory-reared individuals being attracted to the odour of either prey species in the olfactometer. These findings suggest that prior experience mediates responsiveness of C. algerina to the odour of local prey. [ABSTRACT FROM AUTHOR]

Predators that hunt dangerous prey require specialized predatory tactics to avoid counter-attack. Usually, these predatory tactics reduce the probability of detection. The assassin bugs Stenolemus bituberus and S. giraffa rely on stealth or mimicry to prey on dangerous web-building spiders. Paradoxically, however, these assassin bugs tap the spiders with their antennae prior to attacking, leaving the bugs vulnerable to detection and counter-attack. Here, we tested the function of prey tapping. We used a controlled, repeated-measures experiment to assess the responses of spiders (Pholcus phalangioides) to simulated prey and compared their responses after being tapped on the leg (mimicking tapping by Stenolemus) or sham-tapped. We show that tapping can reduce the likelihood that spiders will behave aggressively, in turn lowering the risks of injury for assassin bug predators. Tapping may be an adaptation to reduce intraspecific aggression in prey that is being exploited by their predators. [ABSTRACT FROM AUTHOR]

Spiders are among the most taxonomically diversified orders of predators, but data on the trophic niche of most species are still unknown. Here, we investigated the fundamental trophic niche of two species of jumping spiders, Cyrba algerina (Lucas, 1846) and Heliophanus termitophagusWesołowska & Haddad, 2002, for which data on their realized trophic niche suggest trophic specialization (feeding on other spiders or termites, respectively). We investigated their fundamental trophic niche by means of acceptance experiments. Both species accepted a broader spectrum of prey under laboratory conditions than in the field, suggesting they are euryphagous specialists. [ABSTRACT FROM AUTHOR]

Certainty of paternity is considered an important condition for the evolution and maintenance of extended male care. In some species, males may cannibalize unrelated offspring or abandon the progeny when the uncertainty of paternity is high, or when they take over nest sites or females from other males. However, male protection of offspring can also evolve in situations of uncertainty of paternity, especially when males cannot recognize offspring relatedness. In such cases, males may take care of all their mate's offspring, regardless of paternity. In Manogea porracea (Araneidae), the only known spider species where males care for offspring, males repel competitors by assuming and defending specific positions within a female's web, but females accept multiple partners during the reproductive season. Consequently, males may care for some offspring produced with the sperm of their mate's previous partners. If males cannot detect offspring relatedness, we expect that they will not cannibalize progeny and will actively protect all offspring against predation. The main goal of this study was to investigate whether the extended male care depends on offspring relatedness recognition. Therefore, we experimentally manipulated offspring relatedness and the presence of foster males and two egg predators usually found invading M. porracea webs. We also compared our results with data from an experiment performed by Moura, Vasconcellos‐Neto, & Gonzaga (2017) using the same laboratory procedures, but introducing egg sacs fathered exclusively by the males. Males did not cannibalize offspring and protected the progeny against predation regardless of offspring relatedness. In addition, all males moved the egg sacs to the center of the web, remaining close to the progeny. We conclude that M. porracea males protect all progeny present in their partner's web and increase offspring survivorship regardless of relatedness. We discuss the behavioral and evolutionary implications of our findings, and potential triggers of male care in M. porracea. [ABSTRACT FROM AUTHOR]

In the present study, I reported that the female adult crab spider Thomisus labefactus preyed on a female adult of the wasp spider Argiope bruennichi in the centre of the web. To my knowledge, the case that a large orb-weaving spider A. bruennichi is fed upon by the crab spiders with web-invading is not known previously. It has been shown that T. labefactus, considered commonly as a sit-and-wait predator, also aggressively hunt A. bruennichi, the large web-building spider, attacking its prey at the centre of web. [ABSTRACT FROM AUTHOR]

Several functions have been proposed for silk decorations (i.e., stabilimenta) in spiderwebs. One hypothesis is that web decorations protect spiders from predators, either by concealing the spiders, physically shielding them, or by deflecting predatory attacks. This study uses data gathered in opportunistic manner when studying the behavior of Stenolemus giraffa, an assassin bug that preys almost exclusively on web-building spiders. Stenolemus giraffa approach orb spiders on foot, and usually capture the spiders at the hub region of the web. When pursuing spiders, S. giraffa routinely tap the web with their antennae, and also tap the spiders prior to attacking them. The observations available from this study suggest that S. giraffa got "distracted" momentarily by the decorations in the webs of Purumitra sp. (Uloboridae) and Argiope katherina (Araneidae). In some instances, the assassin bugs tapped these structures for several seconds or minutes instead of tapping the adjacent spiders. In interactions with A. katherina, S. giraffa was more successful at capturing the spiders when the webs lacked decorations; however, sample sizes are small (this could not be tested for Purumitra sp. because only one web lacked decorations). Finally, some of the spiders detected S. giraffa tapping the decorations or that had begun tapping the spiders and that had interrupted this behavior to tap the decorations. The data available suggest that, for S. giraffa, the decorations in these webs interfered with the process of locating the spiders. If further experiments corroborate this idea, this information would be in accord with Hingston's (1927) hypothesis that web decorations can confuse spider predators. [ABSTRACT FROM AUTHOR]

Abstract: Specialist true predators are expected to exhibit higher capture efficiencies for the capture of larger and dangerous prey than generalist predators due to their possession of specialized morphological and behavioral adaptations. We used an araneophagous spider (Lampona murina) and a generalist spider (Drassodes lapidosus) as phylogenetically related model species and investigated their realized and fundamental trophic niches and their efficacy with respect to prey capture and prey handling. The trophic niche of both species confirmed that Lampona had a narrow trophic niche with a predominance of spider prey (including conspecifics), while the niche of Drassodes was wide, without any preference. DNA analysis of the gut contents of Lampona spiders collected in the field revealed that spiders form a significant part of its natural diet. Lampona captured significantly larger prey than itself and the prey captured by Drassodes. As concerns hunting strategy, Lampona grasped the prey with two pairs of legs possessing scopulae, whereas Drassodes immobilized prey with silk. Lampona possess forelegs equipped with scopulae and a thicker cuticle similar to other nonrelated araneophagous spiders. Lampona fed for a longer time and extracted more nutrients than Drassodes. We show that specialized behavioral and morphological adaptations altogether increase the hunting efficiency of specialists when compared to generalists. [ABSTRACT FROM AUTHOR]

Three adult females of Paratrachelas maculatus (Thorell, 1875) were found inside a house in the south of Vienna, in a cellar in Cologne and in a house in Rüsselsheim. Additional notes on diet in captivity are presented.

Some predators sidestep environments that render them conspicuous to the sensory systems of prey. However, these challenging environments are unavoidable for certain predators. Stenolemus giraffa is an assassin bug that feeds on web-building spiders; the web is the environment in which this predator finds its prey, but it also forms part of its preys' sophisticated sensory apparatus, blurring the distinction between environment and sensory systems. Stenolemus giraffa needs to break threads in the web that obstruct its path to the spiders, and such vibrations can alert the spiders. Using laser vibrometry, this study demonstrates how S. giraffa avoids alerting the spiders during its approach. When breaking threads, S. giraffa attenuates the vibrations produced by holding on to the loose ends of the broken thread and causing them to sag prior to release. In addition, S. giraffa releases the loose ends of a broken thread one at a time (after several seconds or minutes) and in this way spaces out the production of vibrations in time. Furthermore, S. giraffa was found to maximally reduce the amplitude of vibrations when breaking threads that are prone to produce louder vibrations. Finally, S. giraffa preferred to break threads in the presence of wind, suggesting that this araneophagic insect exploits environmental noise that temporarily impairs the spiders' ability to detect vibrations. The predatory behaviour of S. giraffa seems to be adaptated in intricate manner for bypassing the sophisticated sensory systems of web-building spiders. These findings illustrate how the physical characteristics of the environment, along with the sensory systems of prey can shape the predatory strategies of animals.

Spiders are powerful predators, but the threats confronting them are numerous. A survey is presented of the many different arthropods which waylay spiders in various ways. Some food-specialists among spiders feed exclusively on spiders. Kleptoparasites are found among spiders as well as among Mecoptera, Diptera, Lepidoptera, and Heteroptera. Predators are found within spiders’ own population (cannibalism), among other spider species (araneophagy), and among different species of Heteroptera, Odonata, and Hymenoptera. Parasitoids are found in the orders Hymenoptera and Diptera. The largest insect order, Coleoptera, comprises a few species among the Carabidae which feed on spiders, but beetles are not represented among the kleptoparasites or parasitoids.

Observations on Thyene imperialis (Rossi, 1846) in Israel, Negev desert, invading a web of Cyclosa deserticola Levy, 1998 are reported. The female leapt into the orb-web to catch Cyclosa spiders. Photographs are provided, and a link to additional film material is given.

ABSTRACT Predators appear to be less frequently specialised (i.e. adapted to restricted diet) on their prey than herbivores, parasites or parasitoids. Here, we critically evaluate contemporary evolutionary hypotheses that might be used to explain the evolution of specialised foraging in predators. We propose a unifying concept within which we define four types of trophic categories using ecological (diet breadth) and evolutionary (degree of adaptations) contexts. We use data on spiders (Araneae), the most diversified order of terrestrial predators, to assess applicability of frameworks and evolutionary concepts related to trophic specialisation. The majority of spider species are euryphagous but a few have a restricted prey range, i.e. they are stenophagous. We provide a detailed overview of specialisation on different prey types, namely spiders, crustaceans, moths, dipterans, ants, and termites. We also review the available evidence for trophic adaptations, classified into four categories: behavioural, morphological, venomic and metabolic. Finally, we discuss the ecological and evolutionary implications of trophic specialisation and propose avenues for future research. [ABSTRACT FROM AUTHOR]

Spiders in the subfamily Argyrodinae are known for their associations with other spiders. These associations include predation (araneophagy), web usurpation and kleptoparasitism. Although the majority of the 239 described species are solitary, ~20 species live in groups in the webs of their hosts. We constructed a molecular phylogeny of argyrodine genera and species in order to investigate (1) the evolution of araneophagy and kleptoparasitism, and (2) group-living and its association with particular types of host webs. We investigated the phylogeny of 41 primarily Asian and American species representing six recognised genera of Argyrodinae, using sequences of four genes: mitochondrial cytochrome c oxidase I (COI) and 16S rRNA (16S); and nuclear 28S rRNA (28S) and histone 3(H3).We used Bayesian methods to reconstruct the ancestral states of three behavioural characters: foraging method, group-living and specialisation on large webs of large hosts. We tested for correlated evolution of group-living behaviour and specialisation on large webs using reversible-jump Markov chain Monte Carlo methods. The molecular phylogenetic analyses support the monophyly of the Argyrodinae. Reconstruction of ancestral states shows the evolutionary pathway of web-invading behaviour in Argyrodinae is from araneophagy to kleptoparasitism, and then to group-living kleptoparasitism. We found the evolution of group-living behaviour is strongly correlated with specialisation on the use of large host webs, which provide a larger food resource than smaller webs. [ABSTRACT FROM AUTHOR]

Behavioural interplay between predator and prey is often overlooked in favour of simpler, more tractable, analyses that focus on just one of the participants. However, a deeper understanding of predator-prey systems can be gained by focusing on the interdependence of predator and prey behaviour, which may be especially complex when the prey has means of retaliation. Web-building spiders are formidable predators of insects, with fangs and venom as weapons, and webs that function both as traps and in transmitting vibrations from intruder movements. Nevertheless, Stenolemus giraffa assassin bugs specialise in preying on web-building spiders using a strategy based on stealth. We illustrate the challenges of pursuing dangerous prey through detailed observations of S. giraffa in pursuit of three spider species. We show that it is difficult for S. giraffa to approach spiders without triggering any response from prey spiders, and that they inhibit escalated responses from the spiders by adjusting their behaviour according to the spider's initial response. The webs of spiders pursued by S. giraffa vary in structure and adhesiveness, and spiders them-selves vary in how they respond to disturbances in their webs, creating diverse predatory scenarios. Despite diversity in web type and prey response, S. giraffa was similarly successful at capturing three spider species investigated here, indicating an ability to effectively monitor prey behaviour and adjust their own behaviour to meet the demands of different predatory scenarios. [ABSTRACT FROM AUTHOR]

Subsocial spiders are located on the continuum between solitary species and social species and are characterized by extended maternal care, some cooperation in foraging and colony activities and dispersal in order to found new colonies. In the genus Anelosimus (Araneae: Theridiidae), up to nine species are thought to be subsocial. One of these spiders, A. baeza Agnarsson (2006), is distributed across a large geographical range from Mexico to southern Brazil, and potential differences in behavior in different populations are unknown. We studied the ecology and behavior of a population of A. baeza in a c!oud forest habitat in Mexico. We tracked the population for ten months, analyzed the degree of cooperation and the presence of associated species, and explored the settling decisions made by dispersing spiders. We show that the breeding season for A. baeza in Mexico differs from other populations elsewhere in South America. Using a kinematic diagram, we recorded the sequence of behaviors involved in subduing and feeding on a model prey species. Larger colonies harbored more associated species. Anelosimus baeza prefers to settle in locations that already contain conspecifics or silk. Our study demonstrates that A. baeza is a viable candidate for research into sociality in spiders and its geographical correlates. [ABSTRACT FROM AUTHOR]

Web-building spiders are formidable predators of insects, and their venom and silk also afford them powerful defence. Nevertheless, some insects specialize on hunting web-building spiders. Stenolemus giraffa is a very large araneophagic assassin bug with an unusually elongated pronotum (‘neck’). This araneophage routinely stalks web-building spiders either by walking onto the web or by leaning into the web to grasp spiders from vantage points on adjacent surfaces. Silk transmits even minute vibrations to resident spiders, and we investigated how S. giraffa circumvents this highly sensitive early warning system to approach spiders undetected. To investigate hunting decisions, and their relation to detection risk, we manipulated the predatory routes available to S. giraffa in pursuits of two spider species that build very different webs. For each prey spider species, S. giraffa tended to take routes that minimized contact with the web and its support lines. Stenolemus giraffa usually resorted to stepping onto the web to pursue spiders only once alternative routes had been explored and probably found inadequate, but even then they avoided the web capture area. For both prey spider species, route preferences of S. giraffa closely reflected risks of detection, indicating a predatory strategy that is finely linked to the perceptual world of the prey. Together with its subtle predatory strategy, S. giraffa''s unusually elongated morphology probably functions to increase its ability to reach spiders from vantage points close to the web without stepping onto the web itself. [Copyright &y& Elsevier]

Communal predators may often need to make especially intricate foraging decisions, as a predator's success may depend on the actions of its neighbours. Here, we consider the decisions made by Portia africana, a jumping spider (Salticidae) that preys on other spiders, including Oecobius amboseli (Oecobiidae), a small prey spider that lives under small sheets of silk (nests) on the walls of buildings. P. africana juveniles settle near oecobiid nests and then ambush oecobiids as they leave or enter the nest. Two or more P. africana juveniles sometimes settle at the same nest and, when an oecobiid is captured, the P. africana juveniles may share the meal. We investigated the joining decisions made by naïve P. africana juveniles. Experiments were based on using lures (dead spiders positioned in lifelike posture) arranged in a series of 17 different scenes defined by the presence/absence of a nest, the lure types present and the configuration of the lures and the nest. Our findings imply that P. africana juveniles make remarkably precise predatory decisions, with the variables that matter including whether a nest is present, the identity of spiders inside and outside a nest and how spiders are positioned relative to each other and the nest. [ABSTRACT FROM AUTHOR]

Although a wide range of vertebrates have been considered in research on numerical competence, little is known about the role of number-related decisions in the predatory strategies of invertebrates. Here, we investigate how numerical competence is expressed in a highly specialized predatory strategy adopted by the small juveniles of Portia africana when practicing communal predation, with the prey being another spider, Oecobius amboseli. Two or more P. africana juveniles sometimes settle by the same oecobiid nest and then share the meal after one individual captures the oecobiid. Experiments were designed to clarify how these predators use number-related cues in conjunction with non-numerical cues when deciding whether to settle at a nest. We used lures (dead spiders positioned in lifelike posture) arranged in a series of 24 different scenes defined by the type, configuration and especially number of lures. On the whole, our findings suggest that P. africana juveniles base settling decisions on the specific number of already settled conspecific juveniles at the nest and express a preference for settling when the number is one instead of zero, two or three. By varying the size of the already settled juveniles and their positions around the nest, we show that factors related to continuous variables and stimulus configuration are unlikely explanations for our findings. [ABSTRACT FROM AUTHOR]

This is the first description of the natural history and behaviour of Stenolemus giraffa Wygodzinsky, an emesine assassin bug (Reduviidae; Emesinae) from Australia. Field data from sites in the Northern Territory and Western Australia, complemented by observations from staged predatory interactions in the laboratory, show that this species is a web-invading araneophage. In the field, S. giraffa was found on rock escarpments, associated with 10 spider species. Spiders of the genus Trichocyclus (Pholcidae) dominated this species’ natural diet at all field locations. Predatory sequences appear to emphasise stealth and were characterised by S. giraffa slowly stalking the resident spider until within striking range. Stenolemus giraffa approached the spiders by breaking silk threads in its path while walking across the rock substrate beneath the web or hanging directly from the web. Observations of S. giraffa being attacked, and sometimes killed, by spiders illustrate that araneophagy is a dangerous strategy for these insects. Natural history and behaviour of most emesine species is currently unknown and so the present study provides an important landmark. Findings from this study add to growing evidence that araneophagy is prevalent in the emesine genus Stenolemus and that considerable variation in predatory tactics occur within this genus. [ABSTRACT FROM PUBLISHER]

Predatory arthropods that specialize in invading webs and preying on the resident spiders (‘araneophagic predators’) face special challenges. As webs are exceedingly good at transmitting vibrations, it is difficult for a web invader to move through the web and remain undetected by the spider. An araneophagic predator that generates vibrations in the web may risk prey escaping or even counterattacking. To increase the chances of an undetected approach, predators may exploit episodes of environmental noise to approach, while their prey’s ability to detect them is compromised (‘opportunistic smokescreen behaviour’). Here we provide the first experimental evidence of convergent opportunistic smokescreen behaviour in an araneophagic insect, Stenolemus bituberus Stål (Reduviidae), which preys on web-building spiders. We tested how two common types of environmental noise, wind and localized vibrations in the web, influence the predatory behaviour and success of assassin bugs when hunting spiders. We found that assassin bugs were more likely to catch the spider in the presence of wind. During episodes of environmental noise, assassin bugs stepped more often and walked in a more continuous manner, apparently exploiting the opportunity to approach while the prey’s sensory system is less able to detect the predator. Changes in predatory behaviour in the presence of environmental noise were not evident when S. bituberus was in an unoccupied spider web. This supports our hypothesis that noise-related timing of behaviour reflects decisions made as part of a predatory strategy, rather than responses to physical disturbance. [ABSTRACT FROM AUTHOR]

Several hypotheses have been put forward to explain the evolution of inaccurate mimicry. Here we investigated the novel hypothesis that inaccurate mimicry (in color and shape) is maintained by opposing selective pressures from a suite of different predators: model-aversive visually oriented predators and model- and mimic specialized predators indifferent to mimetic cues. We hypothesize that spiders resembling ants in color and shape escape predators that typically avoid ants but fall prey to ant-eating predators. We tested whether inaccurate myrmecomorphic spiders are perceived as their models by two types of predators and whether they can escape from these predators. We found that model-specialized (ant-eating) predators captured mimics significantly less frequently than their ant models, because mimics changed their behavior by fleeing predatory attacks. The fastest escape was found in less accurate mimics, indicating a negative association between visual resemblance and effectiveness of defenses. In trials with spider-eating predators, mimics were not captured more frequently than their models. The quality of defensive mechanisms appears to result from opposing selection forces exerted by the predator complex: mimics are more accurate (in color and shape) in microhabitats dominated by model-aversive predators and less accurate in microhabitats with model- and mimic specialized predators. [ABSTRACT FROM AUTHOR]

The article discusses a study on the prey selection behavior of assassin bugs, Scipinnia repax and Nagusta species on jumping spiders. These bugs prey on the social jumping spiders that build nest complexes in vegetation near the shoreline of Lake Victoria. Nagusta species preys on PortiaAfricana and S. repax preys on salticid eggs and also on Nagusta. They avoid ants which suggest that sensory modalities play important role in prey detection.

Instances are documented of finding individuals of Portia africana in the field living aggregated in the webs of other spiders, in the nest complexes of other salticids, around solitary nests of other salticids, and around the nests of oecobiid spiders. Aggregation members included all active juvenile stages of P. africana, as well as adult males and females. More than one individual of P. africana sometimes fed on the same prey. Small juveniles of P. africana were more often than other stages found aggregated and more often observed feeding together. Small juveniles of P. africana surrounded the nests occupied by other salticid genera and nests occupied by oecobiid spiders. When the resident salticid or oecobiid attempted to leave or enter the nest, one of the P. africana juveniles lunged and captured it, after which other P. africana individuals sometimes joined to feed. [ABSTRACT FROM AUTHOR]

Stenolemus bituberus is an araneophagic "assassin bug" (Heteroptera; Reduviidae; Emesinae) that typically is found living in spider webs. We documented the life history of S. bituberus in the field for 13 months, determining its developmental phenology and microhabitat characteristics as well as describing its mating and predatory behaviour. We also included a morphometric analysis of the instars. Our study revealed that S. bituberus is univoltine with five juvenile instars. Although S. bituberus is found in the webs of spiders from a wide range of genera, it is found most commonly in the webs of Achaearanea, Badumna, Pholcus, and Stiphidion. Multiple juveniles often were found on a single web, but adults tended to be more solitary. Stenolemus bituberus appears to have two distinct hunting strategies: "stalking", in which they slowly approach the spider, make contact and then strike; and "luring", in which they attract the spider within range by manipulating the silk with their legs. [ABSTRACT FROM AUTHOR]

All jumping spiders have unique, complex eyes with exceptional spatial acuity and some of the most elaborate vision-guided predatory strategies ever documented for any animal of their size. However, it is only recently that phylogenetic techniques have been used to reconstruct the relationships and key evolutionary events within the Salticidae. Here, we used data for 35 species and six genes (4.8 kb) for reconstructing the phylogenetic relationships between Spartaeinae, Lyssomaninae and Salticoida. We document a remarkable case of morphological convergence of eye ultrastructure in two clades with divergent predatory behaviour. We, furthermore, find evidence for a stepwise, gradual evolution of a complex predatory strategy. Divergent predatory behaviour ranges from cursorial hunting to building prey-catching webs and araneophagy with web invasion and aggressive mimicry. Web invasion and aggressive mimicry evolved once from an ancestral spartaeine that was already araneophagic and had no difficulty entering webs due to glue immunity. Web invasion and aggressive mimicry was lost once, in Paracyrba, which has replaced one highly specialized predation strategy with another (hunting mosquitoes). In contrast to the evolution of divergent behaviour, eyes with similarly high spatial acuity and ultrastructural design evolved convergently in the Salticoida and in Portia. [ABSTRACT FROM AUTHOR]

Three species of Portia ( Portia africana from Kenya, Portia fimbriata from Australia and Portia labiata from the Philippines) were tested with flies Drosophila immigrans and Musca domestica and with web-building spiders Badumna longinquus and Pholcus phalangioides. Badumna longinquus has powerful chelicerae, but not especially long legs, whereas Ph. phalangioides has exceptionally long legs, but only small, weak chelicerae. Typically, Portia sighted flies, walked directly towards them and attacked without adjusting orientation. However, Portia's attacks on the spiders were aimed primarily at the cephalothorax instead of the legs or abdomen. Portia usually targeted the posterior-dorsal region of B. longinquus' cephalothorax by attacking this species from above and behind. When the prey was Ph. phalangioides, attack orientation was defined primarily by opportunistic gaps between this species' long legs (gaps through which Portia could contact the pholcid's body without contacting one of the pholcid's legs). Portia's attack strategy appears to be an adjustment to the different types of risk posed by different types of prey. [ABSTRACT FROM AUTHOR]

We provide a brief report on the feeding behavior of two salticid species in Bijilo Forest, The Gambia: Holcolaetis vellerea Simon 1909 and Menemerus bivittatus (Dufour 1831). The former was observed consuming a giant huntsman spider ?Heteropoda sp. (Sparassidae), which was much larger than itself and represents the first published evidence of araneophagy in this genus. M. bivittatus was frequently observed loitering close to, and orientated towards the nest entrance of stingless bees (Apidae, Apinae, Meliponini), watching them as they entered and left, but no other salticid species were observed doing this. Araneophagy and prey-specific predation behavior are well known in salticids but the behaviors reported here have not previously been documented. [ABSTRACT FROM AUTHOR]

Summary Insular adaptive radiations in which repeated bouts of diversification lead to phenotypically similar sets of taxa serve to highlight predictability in the evolutionary process [ 1 ]. However, examples of such replicated events are rare. Cross-clade comparisons of adaptive radiations are much needed to determine whether similar ecological opportunities can lead to the same outcomes. Here, we report a heretofore uncovered adaptive radiation of Hawaiian stick spiders (Theridiidae, Ariamnes ) in which different species exhibit a set of discrete ecomorphs associated with different microhabitats. The three primary ecomorphs (gold, dark, and matte white) generally co-occur in native forest habitats. Phylogenetic reconstruction mapped onto the well-known chronosequence of the Hawaiian Islands shows both that this lineage colonized the islands only once and relatively recently (2–3 mya, when Kauai and Oahu were the only high islands in the archipelago) and that the distinct ecomorphs evolved independently multiple times following colonization of new islands. This parallel evolution of ecomorphs matches that of “spiny-leg” long-jawed spiders (Tetragnathidae, Tetragnatha ), also in Hawaii [ 2 ]. Both lineages are free living, and both have related lineages in the Hawaiian Islands that show quite different patterns of diversification with no evidence of deterministic evolution. We argue that repeated evolution of ecomorphs results from a rugged adaptive landscape, with the few peaks associated with camouflage for these free-living taxa against the markedly low diversity of predators on isolated islands. These features, coupled with a limited genetic toolbox and reduced dispersal between islands, appear to be common to situations of repeated evolution of ecomorphs. [ABSTRACT FROM AUTHOR]

Foraging is one of the main evolutionary driving forces shaping the phenotype of organisms. In predators, a significant, though understudied, cost of foraging is the risk of being injured by struggling prey. Hunting spiders that feed on dangerous prey like ants or other spiders are an extreme example of dangerous feeding, risking their own life over a meal. Here, we describe an intriguing example of the use of attachment silk (piriform silk) for prey immobilization that comes with the costs of reduced silk anchorage function, increased piriform silk production and additional modifications of the extrusion structures (spigots) to prevent their clogging. We show that the piriform silk of gnaphosids is very stretchy and tough, which is an outstanding feat for a functional glue. This is gained by the combination of an elastic central fibre and a bi-layered glue coat consisting of aligned nanofibrils. This represents the first tensile test data on the ubiquitous piriform gland silk, adding an important puzzle piece to the mechanical catalogue of silken products in spiders., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)