Arachnews: July 22, 2020

Your fortnightly roundup of arachnid art, news, and science.

Neville Park
Jul 23, 2020 · 16 min read

In this edition: fantasy art, new books, court cases, picky black widows, the effects of Arctic climate change, tarantula trafficking, and tons of new species.

Terms in bold are defined in the glossary at the end of the post.

Art & Social Media

A tube-web spider, Segestria florentina Kate Reece
A segestriid’s web in Australia • Nick Porch
A candy-stripe spider (Enoplognatha ovata) eating an aphid • Naomi D. Harvey
An ant-mimicking crab spider (Aphantochilus) found in Brazil • Flávio Mendes
An unidentified mite found on a carpenter bee’s eye • /u/DoYouTasteMetal
A brown recluse detaches a leg to escape from another spider’s web, a behaviour called autotomyMatthew Downen

Education & Outreach

  • “Why don’t I just title this post ‘SPIDER HAS PET CATERPILLAR’ and leave it at that? Why can’t we have nice things without also having to learn stuff? Hush now and receive your bug facts.” This picture of a spider riding a caterpillar is not all it seems. Caitlin Henderson explains what led to this photogenic situation! [Twitter]
  • And here Caitlin Henderson shows us a scorpion-milking demonstration. Don’t try this at home (or with more dangerous scorpions)—this is for research purposes only. [YouTube]
  • For the Natural History Museum of Los Angeles County, Val Hatcher shares valuable information and debunks common myths about the black widow spider. [YouTube]
  • The definitive guide Spiders of North America: An Identification Manual is now available in e-book format, for less than half the price of the paper version. [Baker & Taylor]
  • The much-anticipated Spiders of the World: A Natural History, edited by the late Norman Platnick, is now out. It has profiles of the over 100 spider families* and representative genera from each. [Princeton University Press]
    * Since its publication, several new families have been added—though as far as I know, only one of them (Myrmecicultoridae) represents an entire newly discovered group of spiders rather than a reclassification of existing ones.

Events & News

  • Matthew Downen of the University of Kansas will be doing a live talk on fossil spider research on Friday, July 24, 10 a.m. PDT (5 p.m. UTC). [Facebook]
The endangered Bone Cave harvester Texella reyesi Piers Hendrie
  • Several years ago, Texas landowner John Yearwood, other landowners, the local county, and various anti-environmental conservative groups began a campaign to delist the Bone Cave harvester (Texella reyesi) from the Endangered Species Act (ESA).* Why? It had been found on an 865-acre (3 km²) piece of land* Yearwood owned, which would restrict development of the area. The US Fish & Wildlife Service (FWS) was like, “Fuck off.” The plaintiffs appealed, and a district court was like, “You can’t just tell them to fuck off.” This repeated until eventually the FWS was like, “okay, fine, they might have a point, we’ll look into it.”

    Meanwhile Yearwood and the county were like, “It’s unconstitutional, the ESA is only about interstate stuff and shouldn’t apply to species that only live in one state! We’re suing the government!” and the court was like, “First, you’re wrong. Second, you can’t just sue the government for that, it has to be about a specific thing they did,” and Yearwood and the county were like, “Okay fine, it’s about that time they told us to fuck off.” Now, the Fifth Circuit Court of Appeals has thrown out the case on the grounds that the FWS had to take back their “fuck off” and therefore that decision is no longer in force.

    Conservationists are counting this as a win. However, the FWS is still looking into whether to delist T. reyesi. Their decision is due in October. If you want to speak up for the Bone Cave harvester, you can comment here!***
    * Yes, the Fox News article identifies T. reyesi, an opilionid, as a spider. Yes, this is the calibre of scientific accuracy we expect from Fox News. The Wall Street Journal article was paywalled, okay?
    ** Three square kilometres is a big fucking piece of land, by the way. In Toronto, that covers the area bounded by Bloor to the north, Queen to the south, Spadina to the west and Yonge to the east. The equivalent in other regions is left as an exercise for the reader.
    *** If you want to speak up against the Bone Cave harvester…fuck off.
  • And here’s an interesting Eleventh Circuit Court of Appeals case, this one simpler, thank God. Stephen B. Heard summarizes it here. Basically, the Robinsons, an Alabama couple, filed a home insurance claim because their house was filled with brown recluses (as houses in brown recluse territory are wont to be). The insurance company, Liberty Mutual, denied the claim, because the policy didn’t cover “insects and vermin”. The Robinsons were like, “Gotcha! Spiders aren’t insects!” Liberty Mutual was like, “Look, you know what we mean.” The Robinsons were like, “We certainly do not.” The Court of Appeals sides with the insurance company in a short but pithy decision that goes through centuries of references to show that spiders have always been included in the “ordinary meaning” of “insect”. Dictionary definitions—and the law — aren’t about what people should say, but what they do say.

    Arachnofiles’ verdict: if the Robinsons really knew spiders, they would also know that 1) brown recluses are native to Alabama; 2) the brown recluse is not deadly; and 3) all they need to do is take a few basic safety precautions.
  • Natasha Mhatre of the University of Western Ontario is recruiting Masters and PhD students to study how spiders’ and crickets’ bodies shape how they perceive and communicate with sound and vibration. [Twitter]


  • In the ongoing saga unearthing a prominent social spider researcher’s ethically questionable Microsoft Excel shenanigans, a correction has been issued for this 2014 paper. After removing some data due to “autofill errors”, “duplication of rows” and other anomalies, the authors found their results still held. [Correction 🔓️]


A female western black widow • Sean McCann
  • Here’s a new field study from Catherine Scott and company! Female western black widows (Latrodectus hesperus) are pickier about mates when they live in a more crowded area versus a more isolated one. Females in more isolated areas, who have to wait several days longer for males to start showing up, are more willing to take what they can get. Intriguingly, this implies spiders’ social environments affect the pace and strength of sexual selection. [Paper 🔓️]
  • A short, sweet, and apparently the very first paper on ray spider (Theridiosoma gemmosum) egg sacs parasitized by wasps. A study in Poland found about 20–40% of egg sacs were parasitized, mostly by the wasp Gelis melanocephalus, but some by the wasp Pachyneuron solitarum. It’s possible P. solitarum was preying on G. melanocephalus eggs, which would make it a hyperparasitoid. [Paper 🔓️]
Pardosa glacialis with spiderlings on her back • Amanda Koltz
  • The changing climate in the high Arctic is allowing wolf spiders (Pardosa glacialis) to produce two egg sacs a year. While this is typical for wolf spiders in warmer climates, the Arctic’s long winters used to restrict wolf spiders to one clutch a year. The study is based on eighteen years of data from a long-term monitoring program in Greenland. See also this news story from CNET. [Paper 🔓️]
  • Related: Climate change is already shifting species’ ranges. A recent preprint presents several different scenarios for the fishing spiders Dolomedes fimbriatus and D. plantarius in Scandinavia. D. plantarius are restricted to certain habitats and rarely balloon, which means they cannot travel as far as D. fimbriatus. However, preserving “stepping stones” of habitat sites a few kilometres apart might help them move north as the southern edge of their range becomes inhospitable. [Preprint 🔓️]
  • The leaf-rolling sac spider Clubiona pacifica, common in alder trees in Washington State, often doesn’t bother rolling its own—it will move into leaf rolls made by moth caterpillars (which it also preys on). [Paper 🔓️]
Many spiders enjoy making a meal of frogs given the opportunity • Nyfeller & Altig 2020
  • Roses are red,
    Tarantulas have hair,
    Frog-eating spiders
    are found everywhere.
    (See also this preprint from February.) [Paper 🔓️]
The Brazilian scorpion Tityus pusillus Leonardo Carvalho
  • Roses are red,
    Buthid telsons are round,
    After pooping, this scorpion
    dragged its ass on the ground. [Paper 🔓️]
A huntsman’s silk attachment disc, seen under a scanning electron microscope • Greco et al 2020
  • Spiders’ tough, stretchy dragline silk gets all the press, but there are so many more kinds of spider silk, all amazing in their own way! For example, spiders anchor their dragline silk to the surface they’re walking on with a little spot called an attachment disc, made of pyriform silk. Here’s a paper investigating its mechanical properties—stickiness, stretch, mass, etc. [Paper 🔓️]
  • We’re still learning about the complex physics of how spiders balloon (float on the air using strands of silk). In this preprint, the authors take a kind of model used to simulate microbes’ tails in flowing liquid, and adapt it to simulate spiders dangling from silk threads in air currents. It helps explain why spiders don’t just, like, drop out of the sky. [Preprint 🔓️]
  • Virtually* all spiders are venomous, but aside from a few kinds of spiders, their venom doesn’t have serious effects on humans. Technological advances, which I’m glossing over because I don’t understand them, are allowing scientists to start looking at venom from a wider range of spiders beyond the usual suspects.

    The venom of the European wasp spider (Argiope bruennichi), a large black-and-yellow-striped orbweaver, is “remarkably simple” yet still holds surprises. It doesn’t have many of the small, knotted-looking, often neurotoxic peptides common in other spider venoms. Instead, it mostly contains larger proteins belonging to a group called the CAP superfamily. Animals use CAP proteins in many different ways. The authors suggest that in wasp spider venom, they might be used to liquefy prey. There’s also a few vaguely hormone-like peptides, and a bunch of polypeptides that are totally new.

    It could be that orbweavers’ venom is different because their hunting method is different. However, we know so little about orbweaver venom that a lot more research is needed for any firm answers. [Preprint 🔓️]
    * Except for the family Uloboridae and Holarchaea (family Anapidae).
  • Nearly all spiders have symmetrical genitalia: a male’s pair of pedipalps, a female’s twin genital openings. But there are a surprising number of exceptions! Here’s an overview of all the different kinds of asymmetry and all the species they occur in. The authors also introduce a new category, Chaotic Asymmetry, which sounds like a D&D alignment. [Paper 🔓️]
  • Have you ever wondered how animals find their way around without getting lost? This thorough review paper summarizes what we know about the many forms of animal navigation, then describes many experiments that have been done to test the abilities of spiders, scorpions, and other arachnids. Arachnids have a huge range of sensory capabilities, habitats, and lifestyles, which makes them interesting but neglected subjects for animal behaviour research. [Paper 🔓️]



A male Typhochlaena curumim from Brazil • Fukushima et al. 2020
  • Typhochlaena is a genus of endangered, stunningly beautiful tarantulas native to Brazil. Back in 2012, the species T. curumim was described based on female specimens; now, males have been found. A new paper fleshes out the species description but obscures the rangeTyphochlaena are a hot commodity in the tarantula-keeping hobby, and while collecting and exporting them is illegal, the laws are rarely enforced. Obscuring the exact location is one strategy to protect animals from wildlife traffickers. The authors add that adding Typhochlaena to the IUCN Red List and CITES would help curb trafficking, especially in Europe, where restrictions are lax and many endangered tarantulas are illegally bred and sold. [Paper 🔓️]
  • Oh hey, speaking of sketchy shenanigans, British researchers Sherwood and Gabriel took a look at the type specimen (official specimen, basically) for the tarantula Aenigmarachne sinapophysis. Aenigmarachne was described in 2005 by a fellow named Gunter Schmidt, contains only that species, and no one’s really written anything about it since. After examining the specimen, the authors concluded that’s because Schmidt didn’t know what the fuck he was doing. According to the original paper, the specimen came from near the mainland Costa Rican city of Coco, but the label says it’s from Isla del Coco, 550 km to the west. He says its urticating hairs are Type VI, but they are Type I.

    It turns out Schmidt has a history of getting locations wrong,* probably because he got the specimens from tarantula traffickers who had reasons to be circumspect about where, exactly, they were getting these spiders from. Say, a UNESCO World Heritage Site and national park, like Isla del Coco. This is all hella sketchy. Anyway, Sherwood and Gabriel are currently working on another paper about possible Aenigmarachne species, so stay tuned for further developments. [Paper] [WSC]
    * This 2014 article concludes with the author praising Rogério Bertani for publishing the locations of new Typhochlaena species in 2012, saying they would have found their way into the pet trade anyway. Opinions on best practices in such cases vary (see previous item).
  • A new species of ant-mimic corinnid spider, Myrmecotypus tahyinandu, described from Bolivia; and another Myrmecotypus species, M. niger, found in Bolivia for the first time. The authors speculate that M. niger might be mimicking a Dolichoderus ant. Dolichoderus mimics have been found in Thailand and Australia, but this would be the first from the Americas. [Paper] [Sci‑Hub]
  • While sorting out some misidentified spiny orbweavers (Micrathena) from Brazil, these researchers found an intersex Micrathena ruschii! The spider looked typically male, but with an epigynum and underdeveloped pedipalps. This is the first intersex Micrathena ever found, and only the second from the orbweaver family. (The last was found in 1933.) [Paper] [Sci‑Hub]
The ranges of various short-tailed whipscorpion species in Central America. Short-tailed whipscorpion not to scale. • Monjaraz-Ruedas et al. 2020
  • Difficult-to-classify groups of organisms are often assigned to a wastebasket taxon, the taxonomic equivalent of the kitchen junk drawer. Such is Stenochrus, a Central American genus of schizomids or short-tailed whipscorpions, a little-studied order of arachnids that look like tiny vinegaroons with shorter tails. Now researchers have assembled a family tree of Stenochrus and related genera that shows all the species once assigned to Stenochrus comprise eight different lineages and many belong in different genera altogether. This isn’t the end of the story, though: it turns out the whole damn kitchen needs to be reorganized. [Paper] [Sci‑Hub]


  • A new genus and species of huntsman spiders from Madagascar have been named after young Swedish climate activist Greta Thunberg: Thunberga greta. Four existing species have been transferred to Thunberga from the genera Olios and Rhitymna. [Paper] [Sci-Hub]
  • A new phylogeny of African ground spiders in the subfamily Prodidominae introduces seven new species in three new genera, Kikongo, Kituba, and Yoruba, found in the Democratic Republic of the Congo, Nigeria, and Côte d’Ivoire. There are also eleven new species assigned to existing genera, Austrodomus, Eleleis, and Purcelliana. These spiders are known for the dense tufts of hair on their spinnerets. While the previously known genera live in dry habitats in southern Africa, Kikongo and Kituba are from the central African rainforest and Yoruba is from the savannahs of west Africa. [Paper] [Sci-Hub]


  • A whopping forty-seven new species of Sinopoda huntsmen spiders from across Asia—Brunei, India, Indonesia, Thailand, and Vietnam. Twenty of them were found in caves; one (S. caeca) is completely eyeless and three have reduced or rudimentary eyes. Until now, these nocturnal active hunters were only known from east and southeast Asia. However, we still have yet to figure out how all these species are related to each other. [Paper] [Sci-Hub]
  • Researchers from China have reorganized the Asian species of the family Telemidae, tiny, slow-growing and long-lived spiders found in humid caves and forests aroud the world. Based on newly collected specimens, they add four new genera (Mekonglema, Siamlema, Sundalema, and Zhuanlema) with eight new species, and reclassify many Telema species as Pinelema, Sundalema, and Temofila. Despite the genetic diversity they found, these spiders all look very similar—in fact, an extinct fossil telemid found in amber looks pretty much like modern species. [Paper 🔓️]
  • A new funnel-weaver, Tegenaria lazarovi, found in a cave in southern Turkey. The author notes that it is more closely related to Tegenaria found on Crete and in north Africa than to spiders from the Turkish mainland. [Paper 🔓️]
  • The widow spider Latrodectus dahli, a completely jet-black spider that is surely the gothest of all widows, has been found in Iraq for the first time. While these specimens were found in the southernmost part of Iraq, L. dahli has also been found in Turkey, Azerbaijan, Iran, and Kazakhstan, so the species probably occurs elsewhere in the country. [Paper 🔓️]
  • A new jumping spider species from India, Phintelloides manipur, named after the state where it was found. A few other Phintelloides were also found from locations across India. [Paper 🔓️]
A male Synagelides rosalindae from Sri Lanka • Kanesharatnam & Benjamin 2020
  • Four new Synagelides ant-mimic jumping spiders from Sri Lanka—two of them, S. rosalindae and S. orlandoi, named after the leading couple from Shakespeare’s As You Like It. Rosalind, of course, is a mimic herself—she spends most of the play disguised as a boy. And, like the characters, Synagelides live in the forest. [Paper] [Sci-Hub]
  • Eight new Pimoa spiders from the large hammock-web spider family Pimoidae have been described from Tibet, named after the places they were found. (Pimoids’ closest relatives are the more widespread sheet-web weavers, family Linyphiidae.)[Paper 🔓️]
  • Two new Songthela liphistiid spiders, S. huangyang and S. xiangnan, described from Hunan in southern China. This strange family, with armour-plated abdomens and spinnerets on their bellies, most closely resembles the ancestors of all spiders. [Paper 🔓️]
  • Four species comprising three new genera of linyphiid spiders, Javagone, Javanaria, and Parameioneta, described from Java, Indonesia. This brings Java’s known linyphiid species to 20, 11 of them found nowhere else so far. [Paper 🔓️]


Euoplini trapdoor spiders from Australia: the plug-door/palisade lineage (a, b, e-h); the wafer-door lineage (c, d, i); and the three types of burrows—plug-door (j), palisade (k), and wafer-door (l). Wilson et al. 2020
  • Over the past few years, Australian arachnologists realized that the golden trapdoor spiders, genus Euoplos, actually contained two distinct lineages living side by side—one that builds wafer-door burrows, and one that builds plug-doors and turret-like palisades. Now a group of researchers have produced a new phylogeny based on genetic data, physical traits, and burrow architecture—a challenging task, as many of these spiders haven’t even been classified into different species yet. They just have a bunch of morphospecies—groups that just look like different species but haven’t been formally described yet.

    As a result, they have created a new genus, Cryptoforis (“hidden entrance”), for the wafer-door trapdoor spiders, with a new species, C. hughesae. There’s also a weird outlying branch that may be a third genus. Fun! [Paper] [Sci-Hub]

    P. S. In case you noticed those burrows look familiar, these spiders are in the same family, Idiopidae, as Gaius villosus, a. k. a. the world’s oldest spider.

As always, thanks for reading, everyone! Thanks to Sebastian Alejandro Echeverri for edits. Corrections, additions, and other feedback are always welcome; just drop us a (silk) line at @arachnofiles. 🕷️


  • autotomy: the ability to detach a limb in order to escape from a predator. Many spiders can autotomize their legs and, if they are still growing, can regenerate them when they next moult.
  • ballooning: spiders flying through the air with silk. Not all spiders balloon, but those that do use it to disperse as babies, or sometimes just to get around. They can travel immense distances this way.
  • dragline or dragline silk: the kind of silk that a spider uses as its safety line.
  • epigynum: a female spider’s genital opening, located on the underside of the abdomen.
  • hyperparasitoid: a lethal parasite of a parasite. A parasitoid is a kind of parasite that eventually kills its host; a hyperparasite is a parasite of other parasites. Man, if only there were some pop culture reference I could use to explain these concepts.
  • morphospecies: a bunch of organisms that all look a certain way and probably constitute their own species, it just hasn’t been named yet. You can tell by the way that they are.
  • pedipalps: arachnid appendages that were originally a pair of walking legs. In spiders, they are short, feeler-like limbs that in mature males are modified for sperm transfer. In many other arachnid orders, like scorpions and vinegaroons, pedipalps are large, pinching claws.
  • peptide: a molecule made of a bunch of amino acids strung together. A bunch of peptides strung together is a protein.
  • phylogeny: an evolutionary “family tree”, based on genetic information, physical traits, behaviour, or combinations thereof.
  • preprint: a draft research paper made publicly available before it has undergone peer review. Preprints allow scientists to share vital data and get early feedback on their ideas, but should not be viewed with the same confidence as a published paper.
  • pyriform or piriform silk: literally “pear-shaped”, perhaps after the shape of the silk glands; the kind of silk used to anchor threads to surfaces.
  • range: where a species lives. Figuring out a species’ range and how it will change in the future is key to biodiversity conservation.
  • sexual selection: when traits persist and are passed down in a population because they’re sexy. For example, camouflage persisting because it helps creatures survive is an example of natural selection; showy colours or distinctive courtship behaviours persisting because they help creatures mate is sexual selection.
  • telson: the end of a scorpion’s tail, the part with the stinger on it. Buthid scorpions’ telsons are rounded, giving the end of their tail a bit of an apostrophe shape (‘).
  • type specimen: the specimen that the official description of a species is based on. Type specimens are preserved and stored in collections in museums or other institutions for reference.
  • urticating hairs or setae: the barbed, itchy hairs found on most tarantulas from the Americas. Tarantulas brush off these hairs as a defence mechanism, like tiny porcupine quills. Scientists have identified six different types of urticating hairs.
  • wastebasket taxon: the taxonomic equivalent of that drawer in your kitchen that holds all the things that aren’t particularly related to each other, but don’t clearly belong anywhere else—wine-stoppers, batteries, pencils, toothpicks, napkins, phone chargers, rubber bands, extra spice-jar lids, a tin of mink oil, mysterious keys that don’t open anything, etc. Described a new group of organisms but not sure where it fits? Chuck it in the drawer, promising yourself you will organize it one day.


Arachnids are fascinating.

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