Arachnews: January 27, 2020
A week’s worth of art, news, and scientific research about all things arachnid.
Published in
10 min readJan 27, 2020
In this week’s round-up: the evolution of silk; lots of cool cave arachnids; circadian rhythms in mites and spiders; the diversity of aquatic spiders; how to find face mites; and more. And remember, terms in bold are defined in the glossary at the end.
Art & Social Media
One eye for daytime,
And one for the night,
To watch for our prey
From the world with no light.One eye for futures,
And one for our past,
To see the next monsters,
Much worse than the last…
- Redditor /u/TimeBlossom writes a wonderful poem in response to the writing prompt “Now that [spiders] are nearly extinct, it has become apparent that they were guarding us from something much worse than flies and ants.” (It’s a few months old but was recently crossposted to /r/spiderbro; too awesome not to include.) [Reddit]
Events & News
- Shahan Derkarabetian fears that Nunciella kangarooensis may be extinct after its only known habitat was destroyed by bushfires. [Twitter]
- The sixth Latin American Congress of Arachnology will be held December 13–18, 2020 in Buenos Aires. [VI Congreso Latinoamericano de Aracnología]
Research
Ticks & tick-borne disease
- The black-legged tick Ixodes scapularis can transmit bacteria that cause several diseases. A study in Redding, Connecticut tracked the effectiveness of a three-pronged tick management strategy: reducing the deer population; putting out bait boxes that treat mice with tick-killing pesticides; and applying Met52, a powder or spray containing Metarhizium anisopliae, a fungus that attacks ticks and other bugs. While the combined approaches were effective at reducing ticks and the bacteria that cause Lyme disease, there wasn’t enough data to say whether they also reduce the bacteria that cause babesiosis and anaplasmosis. [Paper] [Sci‑Hub]
- The long, cold winters of the northeastern US kill off the lone star tick Amblyomma americanum. A warming climate means the soil won’t freeze as long or as often, which is what allows the ticks to survive the winter and expand their range. [Paper] [Sci‑Hub]
- The SBm7462 vaccine protects cattle against Rhipicephalus microplus ticks. But what exactly happens to the ticks when they feed on vaccinated cattle? It’s not pretty: their digestive tracts basically get destroyed. [Paper] [Sci‑Hub]
Agriculture
- Many organisms use day-night cycles to regulate their bodies, and throwing off the rhythm can affect their health and development. For two-spotted spider mites (Tetranychus urticae), 14 hours of light and 10 hours of darkness are ideal. Longer days slow their population growth, but don’t make them any more susceptible to pesticides. [Paper] [Sci‑Hub]
- The spider mite Mononychelus planki is a major soybean pest in Brazil. But M. planki is native to the Americas and soybeans aren’t. How did it get by before soybeans? The native plant calopo (Calopogonium mucunoides), also in the legume family, is one possibility. [Paper 🔓️]
- Apricot pollen and moth eggs are part of a healthy, balanced breakfast for the predatory mite Amblyseius swirskii. [Paper]
- Related: the longer-term effects of a diet of almond vs. maize pollen on A. swirskii. [Paper] [Sci‑Hub]
- What’s the most efficient way to check plants for infestations of tomato russet mites (Aculops lycopersici)? One promising new method measures the fluorescent light given off by chlorophyll molecules. How does it stack up against sticky tape and visual examination? [Paper] [Sci‑Hub]
- Two species of predatory mites, the large Lasioseius subterraneous and the small Protogamasellus mica, go head-to-head in a nematode-eating contest. One mite. 100 nematodes. 72 hours. [Paper] [Sci‑Hub]
Ecology & Evolution
- so much depends
upon
piles of bat
guano
in the caves of
Puerto Rico
full of whip
spiders
[Paper 🔓️] - At the Certej mine tailings pond in Romania, the soil is extremely contaminated with heavy metals, many at several times the legal limit. To track the level of pollution and the process of habitat regeneration, scientists looked at populations of soil mites and compared them to similar sites across Europe. [Paper 🔓️]
- In the Western Italian Alps, there are at least 15 different species of Troglohyphantes cave-dwelling sheet-web weavers. What drives this kind of diversification? Are similar species closely related, or have they converged on the same adaptations? [Paper] [Sci‑Hub]
- How spider-rich are the mountainous cloud forests of Taiwan? You could go around and shake every tree. Or you could shake a representative assortment of trees, measure and weigh the spiders you find, and extrapolate that to the whole forest. It turns out to be more accurate if you break the spiders down into several groups based on body shape. [Paper 🔓️]
- The diving bell spider Argyroneta aquatica is far from the only aquatic spider! It’s not even the only aquatic spider in its family, the mesh-web weavers (Dictynidae). A group of researchers constructed a “family tree” of spiders to show that “the life aquatic” has evolved independently multiple times. [Paper] [Sci‑Hub]
Silk
- The Otway odd-clawed spider (Progradungula otwayensis) makes a very unique web that includes a “catching ladder”, two parallel vertical lines with a zig-zag of fuzzy cribellate silk between them. Its complex web-building might shed light on what ancestral araneomorphs were like. [Paper]
- Spiders produce several different types of silk, each with their own uses: major ampullate silk for draglines, aciniform silk for wrapping up prey, piriform silk for attachment points, and so on. Or, at least, that’s what everyone thinks. Comparing 77 different species across 39 families shows that spinneret use and silk composition is very diverse. Most dragline silk is made up of multiple kinds of silk! This has big implications for everyone trying to replicate the strength and toughness of spider silk. [Paper 🔓️]
Anatomy & Physiology
- Pretty much all animals have their own circadian rhythm, an internal clock that regulates body processes roughly in time with a 24-hour day. And spiders’ are really weird! The trashline orbweaver (Cyclosa turbinata), for example, has the fastest circadian rhythm of any animal ever. This fascinating paper looks into the circadian rhythm of male American house spiders (Parasteatoda tepidariorum), and it’s full of surprises. [Paper 🔓️]
- In arthropods, a hormone called octopamine regulates the “fight or flight” response, similar to norepinephrine in mammals. In striped bark scorpions (Centruroides vittatus), raising octopamine levels makes them more aggressive. [Paper]
- Can scorpions smell predators? Desert hairy scorpions (Hadrurus arizonensis) sting more often, and with more venom, when exposed to a rat smell. [Paper 🔓️]
- We know very little about the inner workings of mygalomorphs like tarantulas and trapdoor spiders. These researchers used micro-computed tomography to map the blood vessels of five different mygalomorph species. How are they different from araneomorphs’? I would tell you, but I can’t get past the paywall. [Paper]
Miscellaneous
- “Virtually everyone with a microscope can examine and study Demodex mites.” This wonderful paper outlines the equipment and techniques you need to observe the tiny mites that live in the pores on people’s faces. (For example, they can be extracted with a peel-off mask; an eyelash glued to a rod can be used to turn a mite right side up.) The authors hope to inspire more researchers to work on these woefully understudied creatures. [Paper] [Sci‑Hub]
- The harvestperson Mischonyx cuspidatus, found in Brazil, plays dead more often during the daytime than at night. This is what you’d expect, since playing dead is most effective against visual predators. [Paper]
Taxonomy
General
- Eupodidae is a large, diverse family of soil-dwelling mites found around the world, but we still know very little about how the species are related. For the past ten years, mite taxonomists have debated whether a few genera should be put in their own family, Cocceupodidae, based on differences in their mouthparts. A new molecular analysis comes down firmly on the Yes side. [Paper] [Sci‑Hub]
Americas
- Meet the ticks of South Dakota! This overview covers the 21 species of ticks found in the state, what areas and environments they’re found in, and any disease-causing bacteria they carry. [Paper 🔓️]
- The Cybaeus adenes species group, native to small parts of California, gets a revision. “A number of the clade members may be at risk of great risk of extinction,” the authors warn. [Paper] [Sci‑Hub]
- A new euscorpiid scorpion from Mexico, Megacormus franckei (and descriptions of other Megacormus species). [Paper 🔓️]
- A new solfugid genus and species from Argentina, Curanahuel aconagua. [Paper]
- A list of the opilionids (harvestpeople) found in nature reserves around Buenos Aires, Argentina. [Paper 🔓️]
- A new palpigrade (a. k. a. microwhip scorpion), Eukoenenia igrejinha, found in a cave in Minas Gerais, Brazil. [Paper]
- Once there was a genus of thread-footed mites called Metatarsonemus. Then it was decided they were just plain old Tarsenomus. A new species found in Brazil, M. caissara, leads these researchers to bring Metatarsonemus back again. [Paper] [Sci‑Hub]
- The hard-to-classify mesostigmatid mite Africoseius lativentris gets its own subfamily, Africoseiinae. [Paper]
Europe
- After fifty years without a sighting, the agelenid Histopona paleolithica turns up in a cave in Italy not far from where it was first found. However, the population is at risk due to quarrying and tourist foot traffic. [Paper 🔓️]
- It turns out that 19th century taxonomists were on the right track after all. Molecular analysis and careful examination confirm that ant-mimic ground spider Micaria pulicaria is really two distinct species. “All day long UK arachnologists have been scrambling to look at their specimens and photographs, and it turns out most UK specimens are striped, hence Micaria micans rather than pulicaria,” A. J. Cann writes. [Paper 🔓️]
- A cool new fossil spider, Lutetiana neli, was found in Germany! The only problem is figuring out what family it belongs to. [Paper 🔓️]
- A newly updated map of the pseudoscorpions of Transylvania. [Paper 🔓️]
Africa
- Two new Neobuthus scorpions from Somaliland, N. haeckeli and N. solegladi. [Paper 🔓️]
- A new species of uropodid mite, Centrouropoda bahariyaensis, was found under the wings of red palm weevils in Egypt. [Paper] [Sci‑Hub]
Asia
- Three new Gnaphosa ground spiders from eastern Kazakhstan, including G. prashkevichi, named after the Russian science fiction writer Gennadiy Prashkevich. [Paper] [Sci‑Hub]
- A new Theridion cobweb spider, Theridion odisha, from, well, Odisha, India. [Paper 🔓️]
- Five new Torrenticola and Monatractides water mites from Hainan Island, China. [Paper]
- Five new buthid scorpions in the genus Reddyanus found across southeast Asia. [Paper 🔓️]
- Researchers used genetic analysis to confirm the identity of Dermacentor steini ticks found questing in the forest of Selangor, Malaysia. [Paper] [Sci‑Hub]
- A catalogue of all the oribatid mites found in the Malay Archipelago over the last 113 years. There are still plenty more to record from places like East Timor and Sulawesi. [Paper 🔓️]
- How did “tiny wingless mites” found in seaside algae spread across Japan’s Ryukyu islands? Researchers found a new oribatid mite, Fortunyia churaumi, in their quest to reconstruct the evolutionary history of a family of intertidal mites. [Paper 🔓️]
Oceania
- Nuncia is an unusual opilionid genus: it’s found only in New Zealand and South America. As a first step in sorting out the genus, N. obesa gets an up-to-date description. [Paper]
As always, thank you very much for reading! Many thanks to Sebastian Alejandro Echeverri for edits. Comments, corrections, and suggestions are welcome; just drop us a line at @arachnofiles.
Glossary
- araneomorphs: the group of spider families that includes pretty much any ordinary spider—orbweavers, wolf spiders, jumping spiders, sac spiders, etc.—except tarantulas and other mygalomorphs. You’ll sometimes hear araneomorphs called “true spiders” (though likely not by us). Araneomorphs tend to be smaller and shorter-lived, and their fangs swing in towards each other, like tweezers or scissor blades.
- clade: a group of organisms made up of an ancestor and all of its descendants. This explanation may be helpful.
- cribellate: a kind of silk that is tangly rather than sticky. Spiders make tangles in their silk by teasing it out with a comb (called the cribellum) on their back legs. The first araneomorphs made cribellate silk, but many of their descendants switched to sticky silk (ecribelllate; “lacking a cribellum”).
- micro-computed tomography: using X-rays to scan something one small slice at a time, then putting all the slices together to make a 3D model. Just like a CT scan, but smaller.
- mygalomorphs: the group of spider families that includes tarantulas, trapdoor spiders, and other long-lived, chonky spiders. Their fangs move up-and-down, like a snake’s or a vampire’s. Scientists think that the first spiders to evolve were similar to mygalomorphs.
- questing: a behaviour where ticks sit on the tips of leaves or grasses and wave their front legs, waiting for a host to latch on to.
