Biodiversity of orb-web spiders (family: araneidae) of buner valley, Pakistan

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.

Shaped by the Sun: the effect of exposure to sunlight on the evolution of spider bodies

Body temperature can strongly influence fitness. Some Sun-exposed ectotherms thermoregulate by adjusting body posture according to the Sun's position. In these species, body elongation should reduce the risk of heat stress by allowing the exposure of a smaller body area to sunlight. Therefore, selection should favour more elongated bodies in Sun-exposed than in Sun-protected species. Diurnal orb-web spider species that sit on their webs are more likely to be Sun-exposed, on average, than nocturnal or diurnal shelter-building species. We measured the body elongation of orb-web spiders (Araneae, Araneidae) across 1024 species and classified them as Sun-protected or exposed based on the literature. We found that Sun-exposed species evolved more elongate bodies than Sun-protected ones. Further, we built a model combining traditional heat transfer models with models of thermoregulatory postures in orb-web spiders and meteorological data. The model indicates that body elongation in large orb-web spiders decreases the risk of high body temperatures. Overall, our results suggest that Sun exposure influenced the evolution of body shapes of orb-web spiders.

Outsourced hearing in spiders by using their webs as auditory sensors

Hearing is a fundamental sense of many animals, including all mammals, birds, some reptiles, amphibians, fish and arthropods1,2. The auditory organs of these animals are extremely diverse in anatomy after hundreds of millions of years of evolution3-5, yet all are made up of cellular tissue and are embodied meaning that its functional anatomy is constrained by developmental morphogenesis. Here we show hearing in the orb-weaving spider, Larinioides sclopetarius is not constrained by embodiment but is extended through outsourcing hearing to its proteinaceous, self-manufactured orb-web, and hence under behavioral control, not developmental biology. We find the wispy, wheel-shaped orb-web acts as a hyperacute acoustic array to capture the sound-induced air particle movements that approach the maximum physical efficiency, better than the acoustic responsivity of all previously known ears6,7. By manipulating the web threads with its eight vibration-sensitive legs8-10, the spider remotely detects and localizes the source of an incoming airborne acoustic wave emitted by approaching prey or predators. By outsourcing its acoustic sensors to its web, the spider is released from embodied morphogenetic constraints and permits the araneid spider to increase its sound-sensitive surface area enormously, up to 10,000 times greater than the spider itself11. The use of the web also enables a spider the flexibility to functionally adjust and regularly regenerate its 'external ear' according to its needs. This finding opens a new perspective on animal hearing - the 'outsourcing' and 'supersizing' of auditory function in a spider, one of the earliest animals to live on land12. The novel hearing mechanism provides unique features for studying extended and regenerative sensing13-15, and designing novel acoustic flow detectors for precise fluid dynamic measurement and manipulation16-18.

Three species of hackled-orb web spider genus Miagrammopes from China (Araneae, Uloboridae)

Three species of the genus Miagrammopes O. Pickard-Cambridge, 1870 are described from China, including two new species, M. rutundus Liang & Xu, n. sp. from Guangxi Zhuang Autonomous Region and M. auriculatus Cai & Xu, n. sp. from Tibet Autonomous Region, and one known species, M. bifurcatus Dong, Yan, Zhu & Song, 2004. The female of M. bifurcatus is described for the first time. Both detailed illustration and a distribution map of the three species are provided.

Spider diversity (Arachnida; Araneae) in different plantations of Western Ghats, Wayanad region, India

The study was conducted to explore the spider diversity in different plantations of Western Ghats Wayanad, Kerala state, India. The investigation was carried out for the period from February 2019 to February 2020. A total of 100 species belonging to 74 genera under 20 families were recorded from the selected habitats. This represents 51% families recorded from the Western Ghats, Kerala. The highest species richness was found in the coffee plantation (site A) with 56 species belonging to 12 families. The tea plantation (site B) recorded 27 species belonging to 11 families. The rubber plantation (site C) showed the lowest species richness with 17 species belonging to ten families. Guild structure analyses of the collected spiders revealed nine functional groups viz.., orb-web builders, stalkers, ambushers, cob-web builders, ground runners, foliage runners, tent web builders, sheet-web builders and funnel web builders. The pattern and the architecture of webs varied among different families. During the period of study, five different web patterns were recorded- orb web, tent web, cob web, sheet web and funnel web. It is concluded that the structure of the vegetation is expected to influence the diversity of spiders in different plantations.

Complex behavioral plasticity is not reduced in spiderlings with miniature brains

The brains of smaller animals are smaller than those of their larger relatives, but it is not clear whether their adaptive behavioral flexibility is more limited. Previous interspecific comparisons found that aspects of web construction behavior of very small orb weaving spiders (0.005 mg) were no less precise than those of much larger related orb weavers (30 mg), but the behaviors tested were relatively simple. Here we perform a more sensitive intraspecific test involving the multiple behavioral adjustments of orb web designs made by Leucauge argyra to confinement in very small spaces. Web adjustments of spiderlings as small as ~0.1 mg were compared to previously published observations of ~80 mg conspecific adults. Spiderlings in constrained spaces made all of the complex adjustments made by adults in at least seven independent web design variables, and their adjustments were no less precise. Rough estimates based on previously published data on total brain volumes and the mean diameters of neuron cell bodies suggested that spiderlings and adult females of Leucauge may have similar numbers of neurons, due to spiderlings having smaller neurons and a greater percentage of body tissues dedicated to the brain. We speculate that this neural similarity may explain why L. argyra spiderlings showed no behavioral deficits compared with adults.

The northernmost record of Eriostethus rufus (Uchida, 1932) (Hymenoptera, Ichneumonidae) with an indication of new host, Trichonephila clavata (Koch, 1878) (Araneae, Araneidae) and its web manipulation

Eriostethus rufus (Uchida, 1932) is a polysphinctine ectoparasitoid of araneid spiders (Neoscona spp.) and is endemic to Japan. An individual was collected in Yamagata Prefecture (38º46' N), northern Japan, the northernmost record of the species and also the genus. Its identification was confirmed by morphology and by DNA barcoding. The cocoon was found in a large modified web, which is unique in that the web structure is shaped like an inverted triangle extending to over 50 cm with the cocoon hanging from an ill-defined part of the cocoon web without any organized structure surrounding the cocoon. The host spider of this individual appears to be Trichonephila clavata (Koch, 1878) (Araneidae, Nephilinae) based on several circumstantial evidences. The structure of the modified web suggests that the pre-existing web was partly reused, the orb web was completely removed, and sustaining threads of the barrier web would be newly moored to the substrates. This record means that E. rufus parasitises host spiders of two subfamilies, which is unusual for the group.

Dynamic environments do not appear to constrain spider web building behaviour

Many laboratory experiments demonstrate how orb-web spiders change the architecture of their webs in response to prey, surroundings and wind loading. The overall shape of the web and a range of other web parameters are determined by frame and anchor threads. In the wild, unlike the lab, the anchor threads are attached to branches and leaves that are not stationary but move, which affects the thread tension field. Here we experimentally test the effect of a moving support structure on the construction behaviour and web-parameters of the garden cross spider Araneus diadematus. We found no significant differences in building behaviour between rigid and moving anchors in total time spent and total distance covered nor in the percentage of the total time spent and distance covered to build the three major web components: radials, auxiliary and capture spirals. Moreover, measured key parameters of web-geometry were equally unaffected. These results call for re-evaluation of common understanding of spider webs as thread tensions are often considered to be a major factor guiding the spider during construction and web-operation.