Arachnews: June 8, 2021

Your (ir)regular roundup of arachnid art, news, and science.

Neville Park
Jun 8 · 10 min read

In this edition: earth-toned photos, online conferences to sign up for, loads of pop science coverage, research on golden silk orbweavers and New Zealand’s harvesters, sexy stinging scorpions, fossil spiders, a Batman mite, and more!

Note: due to legal action, the piracy site Sci-Hub stopped adding new articles around the end of 2020. While we still have a large backlog of articles from last year, going forward we must largely rely on open access work and requesting individual papers from the authors. This means we will have to shift to covering a few select papers rather than a comprehensive overview.

If you have (or have written) an interesting arachnid-related paper and you want people to be able to pirate it, you can upload it to Library Genesis using this form (username genesis, password upload).

Terms in bold are defined in the Glossary at the end of this post.

Art & Social Media

This gnarly mite, , was found in France by Julien Tchilinguirian.
A feather-legged orbweaver, by Thilina Hettiarachchi; a well-camouflaged lichen huntsman, , by Caitlin Henderson
An unidentified “periscope” orbweaver, by Nicky Bay; a desert tarantula’s burrow surrounded by blossoms, by dead_blue_deer
A funnel-weaver, by Kevin Wiener; a mite, by Michael Rennert
The crab murder and spider sex happen at the SAME TIME, by the way • Keishu Asada
A mysterious encounter • Dr. Jonathan Kolby
César Favacho finds the Cutest. Spider. Ever.
More delightful footage from the upcoming game Webbed.

News & Events


  • June 10: Dr. Mercedes Burns of the University of Maryland, Baltimore County will be giving a talk on “Daddy Long Legs: The Marvelously Misunderstood Opiliones” for DC’s Audubon Naturalist Society. Registration is $12 for members, $15 for non-members. [Audubon Naturalist Society]
  • The American Arachnological Society’s second virtual conference is set for June 24–30, 2021. Registration is $20 and open to everyone — all kinds of arachnid enthusiasts welcome. The deadline for registration is June 14. [AAS 2021]
  • The first virtual European Congress of Arachnology will take place August 23–25, 2021. There are three slots for keynotes by early career researchers; applications are due by June 15. Attendees must be ESA members. [European Congress of Arachnology]


  • RAEL, a new network of early-career arachnologists across Latin America, recently held their first meeting. They’re also on Twitter at @RAEL_arachno. You may recognize some of the founding members whose research has been featured here—Ivan Magalhaes, Solimary García-Hernández, Fabián García, and many more. [Red de Aracnología Emergente Latina]


  • Daniel Bolnick, editor of The American Naturalist, has published a lengthy blog post summing up the past year and a half or so since it was first discovered that behavioural ecologist Jonathan Pruitt had in many cases provided faulty and apparently fabricated data. Bolnick also lists some lessons learned and goes into the legal issues that have stifled public discussion and collaboration. The only thing he would do differently? Talking to journalists. [Eco-Evo Evo-Eco]
  • Animal Behaviour has published an Expression of Concern for a 2014 paper on Stegodyphus dumicola by Jonathan Pruitt and frequent collaborator Nick Keiser. That is, it’s not considered bad enough (yet) for a full-on retraction, but the data is hella sus. In a Twitter thread, Keiser recommends some other papers to cite instead. [Animal Behaviour]

Popular Science

A orbweaver photographed in Bolivia • Kozue Kawakami, iNaturalist
  • iNaturalist’s Observation of the Week for May 25, 2021 is this tiny orbweaver from Bolivia, found by Kozue Kawakami and her young daughters and eventually identified as the rarely seen Bertrana. She tells iNat, “We might not have survived being cooped up in the pandemic if it weren’t for the ‘bugs’ that accompanied us in all of their forms and colors. Little by little I am becoming familiar with the species that make up the over 5,000 observations that I’ve uploaded. Most are insects and spiders. All have been seen in my small forest of 300 m².” [iNaturalist]
  • Meet Elizabeth Bangs Bryant, the early 20th-century spider curator who was the namesake of the jumping spider Bryantella and the cellar spiders Bryantia and Bryantina (now both in Platnickia). She was among the women whose overlooked contributions at Harvard’s Museum of Comparative Zoology are highlighted in a new online exhibit. [WBUR]
  • “It may seem that there’s an inexorable army of amblypygids on the move, but that isn’t it. Mostly, [Gustavo] de Miranda said, ‘it’s just the lack of people looking.’” Eric Boodman writes about a recent wave of amblypygid discoveries and research; Gustavo de Miranda, Andrea Colla, and Eileen Hebets make appearances. [Undark]
  • It’s no surprise to spider aficionados that spiders, like pretty much all arthropods, are underrepresented in conservation protections. But exactly how underrepresented? A new paper attempts to answer this question for Europe’s spiders. John R. Platt covers the research for The Revelator. Featuring Our Own™ Sebastian Alejandro Echeverri. [The Revelator]
  • Maitry Jani describes the remarkable lives of Stegodyphus sarasinorum, Indian social spiders. They form huge, long-lasting colonies, hunt communally, and support many other species that feed on the spiders or their prey. [RoundGlass Sustain]
  • Cincinnati’s City Beat covers Jenny Sung’s ongoing research at the University of Cincinnati’s Morehouse Lab. Sung (who’s on Twitter at @jychromatic) is researching how paradise jumping spiders (Habronattus) perceive faces, and whether that affects how females choose mates. And yes, there will be a part where she puts eyeliner on their tiny little faces. [City Beat]
Dr. Holly Tuten’s $20 no-sew tick drag
  • Dr. Holly Tuten of the Illinois Natural History Survey has designed a $20 tick drag made from stuff you can get at any hardware store, no sewing required. Tick drags are used to collect ticks from the ground to monitor population levels and collect specimens. [INHS Medical Entomology]
A huntsman spider sits on a security camera at the Canberra Deep Space Communications Complex • Richard Stephenson
  • Giant huntsman attacks Canberra deep space antenna dish! They’re invading! Aaaaahh!…oh, wait… [The RiotACT]


An Evarcha jumping spider hangs by a thread for the night • Daniela Rößler
  • The COVID-19 pandemic has forced researchers around the world to keep their animal research subjects at home. Harvard’s Dr. Daniela Rößler is one of them—the researchers, that is, not the animals. One night she noticed all of her Evarcha arcuata jumping spiders were doing something rather unusual: hanging by a thread of silk from the top of their enclosures. She and her colleagues then found they did the same thing in the wild. But not always! Why do they do it? Why do they sometimes not do it? You can read their theories in a new paper, plus Rößler’s Twitter thread and coverage at Popular Science and NPR’s All Things Considered. [Frontiers in Zoology]
  • Roses are red,
    Lex Luthor steals cakes,
    Check out all these spiders
    found preying on snakes. [Journal of Arachnology]
  • A while back, researchers suggested that golden silk orbweavers’ EXTREME!! sexual size dimorphism may be an evolutionary dead end. Now a new paper from the same lab delves into golden silk orbweavers’ evolutionary history to quantify how fast lineages have diversified or gone extinct. The results are puzzling: neither sexual size dimorphism, ability to disperse, nor habitat seem to be related to speciation or extinction.

    One possible explanation is that speciation and extinction mostly happen in occasional great bursts—like mass extinctions. It is a bit like measuring the average speed of a car in city traffic. Because so much time is spent sitting still, on average the overall speed is very low, like, 12 km/h. But if you measured a car’s speed over a shorter period of time, like an hour, chances are you will capture time when the car is moving at 30 km/h, or even 50 km/h if your transportation planning policy doesn’t take more vulnerable road users’ safety into account, oh fuck I’m doing it again [Scientific Reports]
  • And here’s another paper from the same lab. Golden silk orbweavers also show a great deal of difference within sexes. Even within the same species, there is a lot of variation in how long it takes them to grow, how big they get, and how many eggs they produce. The researchers compared two populations of Trichonephila senegalensis: one from Namibia, with hot summers and cold winters, and one from a milder climate in South Africa. They found that seasonality and increasing day length affect how fast female orbweavers mature. [Biol J Linn Soc] [Libgen]
A neopilionid harvester having a snack. • Erin Powell
  • Dr. Erin Powell’s latest research into New Zealand harvesters from the family Neopilionidae sums up three years of observations on 1) what they eat (pretty much anything, despite having no silk or venom); 2) what eats them (lots of spiders); and 3) how they defend themselves (running away, playing dead, dropping legs). The paper has some amazing photos of harvester behaviour, like competing with other arthropods for food, clumping together for protection, and eating their own exoskeletons after moulting. [Journal of Arachnology]
  • Another paper by Powell & co. takes a closer look at the defensive behaviour of leg-dropping, or autotomy. In the species Forsteropsalis pureora, males come in three types. The first two, “alphas” and “betas”, have large bodies and big, exaggerated chelicerae they use to fight each other for mates. The third, “gammas”, have small chelicerae and smaller bodies overall, and instead of fighting they run around in search of unguarded females. (Think rogues, not warriors.) Surprisingly, these little guys didn’t tend to be missing more legs, nor were they more willing to drop legs in experiments. Maybe the big males’ unwieldy chelicerae make them less nimble and it’s some kind of evolutionary trade-off situation. Or maybe the little ones tend to be snapped up whole and therefore never got collected and counted in the first place. Anyway, regardless of morph, the harvesters who were already missing legs were less willing to drop any more; the cost of this strategy adds up fast. [Animal Behaviour 🔒] [Libgen]
  • What’s a “sexual stinging scorpion”? Surely they mean a stinging scorpion that is sexual (i. e., not parthenogenetic), not a scorpion that stings sexually…right? Right? Wrong. In the Mexican scorpion Megacormus gertschi, males sting the females during mating—or at least that’s what it looks like. Some authors refer to it as “ritualized” or “apparent” stinging. Now a group of researchers have proved that the female scorpions really do get stung! However, they couldn’t find any traces of male venom in the females’ hæmolymph, which hints that males could inject venom but are choosing not to. [Journal of Arachnology]
The graphical abstract was literally just this image. • Taank 2021

Systematics & Taxonomy

  • The prominent animal taxonomy journal Zootaxa recently turned 20, and its anniversary issue includes review articles looking back on the past two decades for various taxa. Arachnids are well-represented, with open access articles on opilionids, mites, and spiders. [Zootaxa]
A–D are various forms of , both male and female. E–K are all different species of ants. • Perger, Rubio & Haddad 2021
  • Three species of Synemosyna ant-mimic jumping spiders found in forests across Bolivia demonstrate the many ways mimicry can work. In S. nicaraguaensis, females mimic Pseudomyrmex simplex, but males come in various colour forms that mimic several other Pseudomyrmex species. In S. aurantiaca and S. myrmeciaeformis, however, spiders change appearance as they grow up, so juveniles mimic different species than adults do. This phenomenon, called transformational mimicry, has been seen in other ant-mimic jumping spiders before, but not in the genus Synemosyna. [European Journal of Taxonomy]
  • Two of the same crew found another new species of ant-mimic jumping spider, Myrmecotypus rubrofemoratus. It imitates the ant Camponotus femoratus, which lives in ant gardens and is very aggressive at defending them. The authors dryly note, “Although C. femoratus does not possess a stinger…the first authors’ painful experience with the bites of this ant suggests that it represents a highly suitable model for mimetic relationships with castianeirine spiders.” [Insecta Mundi]
The prodorsal sclerite of the recently described resembles Batman’s mask. • Bassini-Silva et al. 2021
  • A new species of chigger mite from Trinidad has been named Batmanacarus robini, because part of its head looks like Batman’s mask, and because it was literally found in a bat cave, on a bat. Like Robin, it’s a bat’s trusty sidekick. Trusty, bloodsucking sidekick. [Systematic Parasitology 🔒]
  • Pseudoscorpions—tiny arachnids that look a little like ticks if they had scorpion claws—have been hard to fit into the arachnid family tree. It sounds just too pat for their closest relatives to be scorpions, but that’s what the latest paper from the Sharma lab argues. If pseudoscorpions are most closely related to scorpions (and after that, spiders and amblypygids), this has interesting implications for our interpretation of arachnid evolution, as pseudoscorpions also display behaviour like parental care and courtship dances. That suggests these behaviours didn’t arise independently in several branches, but were inherited from an ancestor they all share. [Molecular Biology & Evolution]
  • A fossil spider found in Brazil, the earliest spider from the family Palpimanidae found so far, has been named after iconic Brazilian drag queen and singer Pabllo Vittar. On Twitter, lead author Matthew Downen reflects on mistakes made in the light of an increased push to decolonize palaeontology. [Journal of Arachnology]

As always, thanks for reading! Got any additions, suggestions, or corrections? Drop us a (silk) line on Twitter at @arachnofiles. 🕷️


  • autotomy: detaching limbs, used as a defense mechanism to escape predators. Many arachnids are able to autotomize, and some are capable of growing the legs back if they moult again.
  • hæmolymph, also hemolymph, haemolymph: the arthropod equivalent of blood. While our blood uses iron to carry oxygen, theirs uses copper—hence its bluish or greenish appearance.
  • parthenogenetic: capable of parthenogenesis, that is, females reproducing without males. Parthenogenesis has been observed in various kinds of arachnids—mostly mites, but some scorpions and a few spiders and harvesters as well.
  • transformational mimicry: a form of mimicry where individuals change appearance as they grow, so they mimic different species at each life stage.


Arachnids are fascinating.

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