New Deep Look video is about _Tetragnatha_ mating! Great footage: https://youtu.be/-CqBIjhpL0Q
#Arachnews #spiders #SpiderSex #nsfw (unless you work as an arachnologist I guess)
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the nerds are at it again
a new species of ghost spider (family Anyphaenidae) from Brazil's Atlantic forest has been named _Eldar galadrielae_ (the Eldar are the Elves in LotR)
paper: https://dx.doi.org/10.1007/s00114-025-01982-4 
// PDF free if you have an account at the World Spider Catalog: https://wsc.nmbe.ch/reference/18403
New research from the Hebets Lab at University of Nebraska Lincoln: _Agelenopsis_ grass spiders in noisy urban environments weave webs with built-in noise dampening—as opposed to their rural cousins, who built more sensitive webs when researchers turned up the volume.
From the NYT article linked below:
> “While animal sensory systems can, and do, certainly adapt over evolutionary time to changing environmental conditions, this takes time,” Dr. Hebets said. “Behavioral changes, however, can be immediate.”
This offers an intriguing tangent: webs are part of a spider's sensory apparatus but are constantly re-built, and behavioural plasticity lets them "evolve" much faster—an evolution you can't track by looking at physical traits alone.
Anecdotally, _Agelenopsis_ are masters at adapting their flat sheet webs to even the unlikeliest urban environments! So it's not a surprise they are adaptable in other ways as well.
Paper: https://doi.org/10.1016/j.cub.2025.02.041
NYT article: https://www.nytimes.com/2025/03/22/science/spiders-webs-noise-pollution.html // https://archive.ph/Mu7KJ
I did not expect to read the phrase "males have terminal nuptial gift sacs on their penises" today but here we are
A delightful paper comparing mating behaviour across _Leiobunum_ harvester species which have, or lack, nuptial gift-giving, out of Mercedes Burns' lab at the University of Maryland Baltimore County: https://doi.org/10.1016/j.anbehav.2025.123150 
#Arachnews: Ximena Nelson, a specialist in spider behaviour (particularly jumping spiders), has a book out! _The Lives of Spiders: A Natural History of the World's Spiders_, from Princeton University Press: https://press.princeton.edu/books/hardcover/9780691255026/the-lives-of-spiders
Review in the New Yorker, if you can stand the overwhelmingly self-indulgent "oooh spiders are so icky and scary" tone: https://archive.ph/XqdhD
press.princeton.eduThe Lives of SpidersA beautifully illustrated guide to the natural history and breathtaking diversity of spiders around the world
> As of 2025, there are over 52,000 species of spider known in our plane of existence (World Spider Catalog, 2025), with many more awaiting discovery. This does not take into account spiders that may exist in other planes of existence, which, until now, have never been studied.
It's a bit early but this is quite possibly the best arachnid paper I've read, and will read, all year: Marc Milne & Shahan Derkarabetian construct a phylogenetic tree of arachnids in Magic: The Gathering.
If you don't know much about MtG, arachnids, or how biologists classify species, you'll definitely learn something from this paper!
Uhhhhh holy shit no one told me _Dolomedes_ & co. got moved from Pisauridae to their own family, Dolomedidae? https://wsc.nmbe.ch/family/158/Dolomedidae
Morris, Hazzi & Hormiga 2025: https://doi.org/10.1016/j.ympev.2024.108247
If you have a WSC account you can get the PDF here: https://wsc.nmbe.ch/reference/18059
#Arachnews: folks at Gabriele Uhl's lab have discovered that male wasp spiders (_Argiope bruennichi_) have special sensory organs, called wall-pore sensilla, on their legs which they use to smell females' airborne pheromones. They also found wall-pore sensilla in other adult male spiders, and evidence suggests they evolved independently across the spider tree of life. Many questions still remain about spider smell!
https://theconversation.com/spiders-smell-with-their-legs-new-research-246691
https://www.pnas.org/doi/full/10.1073/pnas.2415468121
The ConversationSpiders ‘smell’ with their legs – new research
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The Conversation UK
Ooh. Some cool new research on slingshot spiders (_Theridiosoma gemmosum_).
"Saad Bahmla (Georgia Institute of Technology, USA) and colleagues, including Todd Blackledge (University of Akron, USA), discovered in 2021 that they could trick the wily arachnids into releasing their ballistic nets by simply clicking their fingers. Might the weapon-wielding spiders be listening to deploy their webs even before their victims have blundered into them? Sarah Han, also from the University of Akron, and Blackledge decided to test the spiders’ reactions […]
"Sure enough, the spiders let loose their webs when the flapping mosquitoes were in the vicinity. But when Han took a closer look at the movies they had recorded, it was evident that the insects never touched the webs with their protruding front legs. The spiders were capable of launching the structures even before an insect impacted the web. And when Han tried the same trick, but this time waving a tuning fork, pitched at the tone produced by the flies’ whining wings, in front of the web, the arachnids still released their webs to rocket forward. The spiders must have been listening for the approaching insects, letting loose their webs when the mosquitoes were in range, before the insect had blundered into it."
Article (like normal people newspaper style article, not a scholarly article): https://journals.biologists.com/jeb/article/227/23/jeb249732/363194
Paper: https://journals.biologists.com/jeb/article/227/23/jeb249237/363202
#Arachnews #OpenAccess #arachnids #spiders #SpiderBehaviour • #Araneae #Theridiosomatidae
tfw you're a _Dinoponera gigantea_ ant colony in the Brazilian Cerrado and one day a _Diplura_ curtain-web spider just straight up moves into your anthill and you all need to move https://periodicos.uefs.br/index.php/sitientibusBiologia/article/view/11292/9400
Note: _Diplura_ are sometimes called funnel-web spiders, but they are in family Dipluridae, which is different from Australia's funnel-web spiders (families Atracidae, Hexathelidae, etc.) Australia's funnel-webs are medically significant, Dipluridae are not. This is why you never rely on common names.
A team including some of the folks that brought you "The global spread of misinformation on spiders" (https://doi.org/10.1016/j.cub.2022.07.026) (incl. @arachnonaut!) has done it again with "The influence of spider news on online information-seeking": https://doi.org/10.1371/journal.pone.0308169
They compared data from Google Trends, Wikipedia, and iNaturalist with spider news stories (including data on their sensationalism & accuracy) from 2010-2020. They conclude that "some news stories have a measurable (although weak) effect on the online information-seeking behaviour of the general public. More broadly, our results tend to confirm that the fear of spiders has a cultural component."
paper title of the day:
Magalhaes ILF, Iuri HA, Brescovit AD, Pizarro-Araya J (2024) The tiniest violin: the male of Loxosceles vallenar (Araneae, Sicariidae). ZooKeys 1206: 327-342. https://doi.org/10.3897/zookeys.1206.122469
"With carapace lengths smaller than 2 mm, the newly discovered males of _L. vallenar_ are the tiniest members of the genus."
ZooKeysThe tiniest violin: the male of Loxosceles vallenar (Araneae, Sicariidae)In recent years, several endemic species of Loxosceles, violin spiders, have been described from the North-Central Chile biodiversity hotspot, some of which have ambiguous placement within the species groups of the genus. In a recent expedition to the Atacama region, we collected male specimens representing new records of two recently described species: Loxosceles vicentei Taucare-Ríos, Brescovit & Villablanca, 2022 and Loxosceles vallenar Brescovit, Taucare-Ríos, Magalhaes & Santos, 2017 (Araneae, Sicariidae). Males of the latter are hitherto unknown and are here described for the first time. Examination of the morphology of these species revealed characters such as an embolic keel and digitiform median receptacles, which suggest they do not belong in the laeta species group, but rather in the spadicea species group, which is briefly re-diagnosed. With carapace lengths smaller than 2 mm, the newly discovered males of L. vallenar are the tiniest members of the genus. In addition, males of this species bear strong macrosetae in the clypeus, a sexually dimorphic character not previously reported in Loxosceles.
you had me at "maternal regurgitation" https://doi.org/10.13156/arac.2024.19.7.962
BioOne CompleteMaternal regurgitation in Anelosimus baeza and A. nigrescens (Araneae: Theridiidae)In the social behaviour of arthropods, regurgitation (feeding of the young) is a component of maternal care. In this paper, we describe regurgitation under laboratory conditions in species that share the same habitat, one subsocial (Anelosimus baeza) and a species considered to be solitary (Anelosimus nigrescens). The recently emerged spiderlings were fed by five of the nine A. baeza and six of the eight A. nigrescens females. In both species, the mother is critical in the initial stages, as spiderlings cannot feed themselves until the second instar. Our data suggest that A. nigrescens may be a subsocial species; this is the first report of regurgitation in these species. This fact shows the importance of regurgitation contributing to cooperation in live spiders. Future studies on maternal behaviour in these species are needed to elucidate the degree of sociality.
Carrying egg sacs doesn't slow down mother _Pardosa_ wolf spiders! https://journals.biologists.com/jeb/article/227/3/JEB246579/342682
The Company of BiologistsCarrying an eggsac is not an issue for wolf spidersPeople are often afraid of spiders. Perhaps one of the most fearful moments is when they move fast unexpectedly, even though they might be trying to avoid humans. And the spider's ability to move fast or slow depends on the temperature of the environment, because they are ectothermic creatures. It is also known that changes in their body mass and their build can influence their moving speed. However, there is not much information on how the combination of environmental temperature and changes in body composition together influences how fast spiders move. This prompted scientists from various countries in Latin America and the USA to investigate how temperature and carrying an eggsac affects the ability of female Pardosa wolf spiders (Lycosidae) to move.Damián Villaseñor-Amador from the Universidad Autónoma de Mexico, and researchers from Brazil, Chile, Argentina and the USA collected 86 female wolf spiders from the sub-Alpine zone of the Buena Vista peak in the Talamanca Mountain range, Costa Rica, where temperatures can be extremely high or low, and conditions can change suddenly. Thirty-six of the spiders were carrying eggsacs, which can weigh as much as 77% of their body mass, while the remaining females were eggsac-free. After transporting the spiders in individual tubes to a warehouse 22 km away, Villaseñor-Amador and colleagues placed half of the eggsac-carrying females in a cooler for 5 min, to chill the spider. Then, they monitored each spider as it ran around an arena with a leaf floor covered in clear plastic, marking the spider's locations on the plastic surface as the animal moved, before using a cotton string to track the markings and measuring the string length to calculate the distance travelled by the spider. Next, they placed the remaining egg-carrying females in a 30°C heater for 5 min to raise their temperature before recording the warmed spiders’ movements. The team then tracked the movements of the females that had no eggsacs at 7°C, 30°C and also at room temperature (13°C), in addition to recording how long all of the spiders (with and without eggsacs) kept moving until they paused for at least 5 s.Not surprisingly, the wolf spiders moved faster when the environment was hotter; however, the largest spiders moved the slowest in hot temperatures, while the opposite occurred in cold temperatures. This may be because it is easier for the smallest wolf spiders to heat up to move faster in hot conditions. In contrast, at cold temperatures, the largest spiders may be more efficient at using their energy.However, in contrast to expectation, the heavy burden carried by females with eggsacs did not affect their speed. Villaseñor-Amador and colleagues suggest that Pardosa wolf spiders may modify their body posture to compensate for the extra weight and drag that the eggsac generates. Alternatively, egg-carrying females may simply invest more energy in movement, allowing them to run as fast as unburdened females.So, the extreme temperatures experienced by Pardosa wolf spiders in the Talamanca Mountains affect how fast the animals can move, yet their speed is unaltered when carrying an extremely heavy load, allowing them to escape predators as successfully as egg-free females, to ensure the future of the next generation.
#Arachnews and #ClamFacts together at last. These folks at Finland's Aalto University have devised a new biomimetic adhesive based on spider silk and mussel foot protein: https://doi.org/10.1002/admi.202300934
Meet _Chilobrachys natanicharum_, a newly described tarantula from Thailand with legs that iridesce with "a blue-violet hue resembling the color of electrical sparks". You seriously gotta see this. https://zookeys.pensoft.net/article/106278/
An article about some previously described metallic blue tarantulas from southeast Asia, including another Chilobrachys: https://www.smithsonianmag.com/smart-news/turquoise-tinted-tarantula-discovered-sri-lanka-180972990/
Some tidbits of #OpenAccess #Arachnews:
- a new high-level #phylogeny of #Solifugae, the bizarre and enigmatic arachnids known as "camel spiders", "wind scorpions", "sun spiders", and so on. From Siddharth Kulkarni at UW-Madison's Sharma lab and featuring all the usual suspects in the authors list, like solifuge expert Paula Cushing, Efrat Gavish-Regev, Danilo Harms, etc. https://doi.org/10.1016/j.isci.2023.107684
- #tarantulas (family #Theraphosidae) in the wild in Argentina! Including many Plesiopelma aspidosperma and "the first published color photograph of an adult specimen of Cyriocosmus versicolor based on a reliable taxonomic identification". 
https://www.researchgate.net/publication/373649580
do you think 50 years of breeding mutant spiders and releasing them into the local population has had an effect 
https://peerj.com/articles/16011/#p-19
A quick #Arachnews roundup:
- Andreas Fischer's MS thesis brings together research on _Steatoda grossa_ web recognition, whether plants' stress scents deter spiders (not really), and what *does* repel them (European fire ant scent). https://summit.sfu.ca/item/36449
- Can the invasive longhorn tick catch the bacteria _Rickettsia ricketsii_ from animals that have previously been fed on by infected American dog ticks? A new CDC study concludes it's extremely unlikely: https://doi.org/10.1093/jme/tjad107
- Dr Luis Roque is moving his arachnid taxonomy updates from the Arácnido Facebook group to a dedicated website: https://www.aracnidotaxonomy.com/
- The Insect Welfare Research Society has grants available for grad students researching insect/understudied invertebrate welfare and sentience. Zoom info session on Sept 1 2023, 4pm BST. Details: https://www.insectwelfare.com/student-research-awards
summit.sfu.caContributions to integrated management of synanthropic spiders
#Arachnews: The 2023 Arnold Berliner Award for "excellent, original, and interdisciplinary" research goes to Cynthia Tedore for the 2022 paper that found the jumping spider _Saitis barbipes_ does not have red photoreceptors and the distinctive red patches on males' legs, which they wave and display to potential mates, are probably invisible to them. However, they *can* see UV. https://link.springer.com/article/10.1007/s00114-023-01870-9
Original paper: Glenszczyk, M., Outomuro, D., Gregorič, M. et al. The jumping spider _Saitis barbipes_ lacks a red photoreceptor to see its own sexually dimorphic red coloration. _Sci Nat_ 109, 6 (2022). https://doi.org/10.1007/s00114-021-01774-6