Arachnews: August 2019
Published in
11 min readSep 24, 2019
A month’s worth of art, news, and science about our arachnid friends.
Art & Social Media
- There’s a new Lucas the Spider short:
- An amazing origami scorpion. Comes with a pattern, if you dare!
- A mite on a bug that caught a spider that…caught a beetle? There’s a lot going on here.
- Check out Nicky Bay’s photos of this rainbow-faced Tapponia lynx spider!
- Nick Porch captures this stunning pair of red-and-black spiders:
- A rare sighting of a hooded tickspider!
Education & Outreach
- Mark Cocker contemplates the fen raft spider: “Kneeling for hours on the dyke bank at arm’s length from my photographic prey, I steadily adjust to the spider’s micro-world of water and weed, striped by saw-edged water-soldier spikes and their shadows.”
- On Quora, Joseph T. Lapp answers the question “Can a spider be entangled in its own web?”
- Behind Emanuele Biggi’s famous photo of a tarantula and its tiny frog roommate. “Seeing such a unique relationship is like being the first man to meet aliens — amazing and breathtaking.”
- Our own Sebastian Alejandro Echeverri profiles the dedicated volunteer naturalists tracking Atypus snetsingeri, a purseweb spider found around Philadelphia. “‘There were some [people] that were so curious, they were willing to lay on their bellies, and look into holes to see these spiders, rain or shine.’”
Events & News
- Spiders and arachnids were represented at several outreach events, including Guelph Bug Day, an Ontario BioBlitz, and the British Birdwatching Fair. Some highlights:
- Doctors find brown recluse spider in Kansas City, MO woman’s ear. These stories are usually unfounded clickbait, but I think this is actually plausible.
First, this is well within Loxosceles reclusa’s range, where they are very common. Second, there’s actually a photo of the spider, and its appearance is consistent with a brown recluse’s. Lastly, its reported behaviour checks out: it didn’t bite. I do not blame the lady for sleeping with ear plugs in from now on, though! - Two new preventative treatments for Lyme disease are in the works, reports Brittany Flaherty at STAT. One is a vaccine called VLA15, targeting the six most common species of the tick-borne bacteria Borrelia; the other is Lyme pre-exposure prophylaxis (PrEP), which delivers an antibody. Hopefully these are more successful than the vaccine LYMErix, which was pulled from the market in 2002 in the early years of vaccine hesitancy.
Research
Note: Sci-Hub is a website that bypasses scientific journals’ paywalls, allowing non-academics to access new papers.
Spider Sex
- In black widows, sexual competition is fierce. Hordes of males traverse terrain rife with predators, racing to be the first to a female. They can pick up the scent of her pheromone-laden silk — but new research reveals it’s even faster to follow the silk trails of their rivals. Read lead author Catherine Scott’s account of the Great Black Widow Race, which was also covered in the New York Times and Discover Magazine. [Paper] [Sci-Hub]
- All kinds of spiders use silk for sexual communication! In the mygalomorph spider Acanthogonatus centralis, males can tell if a female’s already mated from her tasting her silk. [Paper] [Sci-Hub]
- Gotta love a paper that just says what it is on the tin: “Females of a cannibalistic spider control mutilation of their genitalia by males”. Many female spiders can mate with, and use sperm from, multiple males. To increase their chances of fertilizing more eggs, Larinia jeskovi males use special structures on their pedipalps to cut away a female’s scape (a little poky-out bit on her genitalia) to prevent other males from being able to mate with her. But it takes two tries for them to do it, so if the male doesn’t meet her standards or there’s other males around, the female can prevent it by cutting mating short. By eating them. Yep. [Paper] [Sci-Hub]
- Male spiders can try to mate with multiple females, but it seems that this has risks. In the wolf spider Aglaoctenus lagotis — which, by the way, is a weirdo that lives on webs instead of running around like a normal wolf — males seem to transfer less sperm with each mating, possibly increasing his chances of getting attacked by the females. Females that received less sperm after mating were more likely to attack a male! [Paper] [Sci-Hub]
- Male Pardosa pseudoannulata wolf spiders likely don’t get a second chance to mate — it seems that females can tell if a male has already mated, and they turn him down far more often. [Paper] [Sci-Hub]
- Okay, but how long should male spiders have sex for? Longer matings mean more chances to transfer sperm, but cannibalistic females mean shorter matings are safer. In the orb-weaver Argiope aurantia — “which exhibits the shortest copulation in any spider and rivals the honey bee for shortest copulation reported for any arthropod with internal genital coupling” — males finish up in only 3–4 seconds. [Paper] [Sci-Hub]
- Wolf spiders like Schizocosa floridana court females with multi-modal vibratory songs that includes thumps, taps, and chirps. As the day heats up, the changing temperature affects not only how males perform their songs, but how females choose males! [Paper] [Sci-Hub]
Ecology
- “Climate change making spiders more aggressive,” the media widely reported. The actual research was on Anelosimus studiosus, a spider that is very unique — it lives in colonies. Now, spiders have individual personalities; some are bolder, others more timid. Anelosimus colonies, each comprising hundreds of females, can tend to one or the other. When tropical cyclones hit, aggressive colonies — more territorial and more active hunters — were more likely to survive than docile ones. In unaffected areas, it was the other way around. Read Katherine J. Wu’s Nova story about the research, as well as Sergio Henriques’ take on the bigger picture. [Paper 🔓]
________
Edit (Feb. 9, 2020): this paper is currently being examined for potential issues. You can check the status here. - Researchers from Brazil and Argentina (including our own Ivan Magalhaes) studied the evolution of the six-eyed sand spider, Sicarius, using both DNA and physical characteristics. They discovered that the sand spiders of the Americas and Africa form two groups that split about 100 million years ago, approximately when these two continents separated. It seems these spiders have only ever thrived in dry environments. However, they have shifted multiple times between different types of dry environments, such as deserts and dry forests. [Paper] [Sci-Hub]
- Spiders basically have three different types of lifestyle: web-weavers, ambushers, and active hunters. Each prey on different kinds of insects and have distinct ecological roles. But what happens in a complex ecosystem when there’s multiple types of prey to choose from? These researchers in Portugal paired up representatives from each group with fruit flies, moths, and crickets to see how their behaviour changed. [Paper] [Sci-Hub]
- Terrestrial isopods (a. k. a. woodlice, pill bugs, roly-polys, etc.) are unappealing prey for several reasons. They’re heavily armoured and many can roll up into balls, like pangolins and armadillos. They accumulate heavy metals in their bodies much more than other creatures, partly from their diet of decaying plant matter. Yet some Dysdera spiders have repeatedly evolved to specialize in eating woodlice; it happened twice in the western Canary Islands. Here’s a study of the molecular changes underlying this shift. [Paper] [Sci-Hub]
- Ixodes scapularis, the tick that transmits Borrelia burgdorferi, the bacteria that causes Lyme disease, is commonly known as the deer tick. But it feeds on many other animals, like mice. Lab experiments have suggested that full ticks detach and live in mouse nests. Entomology Today reports that by tracking mice to their nests, University of Wisconsin-Madison researchers have confirmed this behaviour in the wild for the first time. [Paper 🔓]
- Spiders can catch agricultural pests, but how well they do so seems to depend on their hunting style. Orbweavers in guava and citrus farms mostly caught pests, but social sheet-web spiders mainly ate beneficial species. [Paper] [Sci-Hub]
- Unlike some plants that reproduce well after a fire, spiders are hit hard. Populations of wandering spiders seem to take longer to recover than web building spiders. [Paper] [Sci-Hub]
Anatomy & Physiology
- Seems like just about every abstract into arthropod senses has to mention possible technical applications of the research. Well, these absolute madmen have gone and designed a flexible pressure sensor inspired by the scorpion’s slit sensillum. [Paper 🔓]
- Scorpions have these weird, rake-looking sensory organs on their bellies called pectines! And scientists have hooked up electrodes to scorpions brains to figure out how these pectines work. [Paper] [Sci-Hub]
- Speaking of weird organs on the bottoms of arachnids, solifugids have their own. These are called malleoli, and look like little fan-shaped brushes, but seem to work differently! [Paper] [Sci-Hub]
- We still know very little about the central nervous systems of spiders and what chemicals are involved. Here’s a first look at the neurons that make dopamine and norepinephrine in the wolf spider Hogna lenta and the jumping spider Phidippus regius. [Paper] [Sci-Hub]
- Just like most animals, how a scorpion responds to a threat depends on what the threat is and on the individual; younger Titys pusillus, despite having working venom, tend to flee, while adults are more defensive. [Paper] [Sci-Hub]
Intelligence & Tools
- Aw yiss, it’s another Cross & Jackson paper on Portia intelligence. Their latest experiment tested Portia africana’s ability to plan in advance whether to take a direct route to a target, or make a detour. Did Portia make the smart choice? Of course she did. Clever girl. [Paper] [Sci-Hub]
- Some species of spiders make fuzzy cribellate silk, which captures prey with nanofibres that chemically fuse with insect exoskeletons. Over time, many spiders lost the ability to make cribellate silk and instead evolved ecribellate sticky, glue-covered silk — the foundation of most webs that are suspended in the air, rather than laid on the ground. Now most spiders are ecribellate, and only a few kinds of spiders make cribellate aerial webs. Why did this happen so widely and so often? A new paper looking at the evolution of spiderweb architecture suggests physical constraints play a role: it’s really hard to make strong anchor points for aerial webs using cribellate silk. Maybe losing cribellate silk is what made aerial web architecture really take off! [Paper] [Sci-Hub]
Taxonomy
Spiders
New records
- Caitlin Henderson (of Minibeast Wildlife and She’s Got Legs) and Graham Brown have found Argiope catenulata for the first time in Australia. The large, stunning silver spider is known from rice paddies across Asia, and appropriately enough was found in the Northern Territory’s Fogg’s Dam, “constructed as part of a failed rice-growing project in the 1950s”. [Paper 🔓]
- Lots of wonderul photos from this survey of the spiders of the Eastern Ghats in Odisha, India. The researchers found 138 different species, 40 of which are endemic to India and 19 of which are only found in Odisha. [Paper 🔓]
New species
- Four new tree-dwelling sac spiders from central and southern Africa [Paper 🔓]
- “Fuzzy, turquoise-tinged, and big enough to comfortably hug a donut”: meet Chilobrachys jonitriantivansicklei, a lovely shimmery-blue tarantula from the rainforests of Sri Lanka. [Paper 🔓]
- Five new species of (various types of) ground-living spiders from several Greek islands [Paper] [Sci-Hub]
- Four new species of Draconarius grass spiders from Tibet [Paper]
- A new species of Onoculus crab spiders from the Amazon is remarkable for its huntsman-spider-like flatness and mossy colors. [Paper 🔓]
Revisions, etc.
- Some mixups in the genus Gnaphosid spider genus Scopoides: a bunch of species got combined into new ones. [Paper] [Sci-Hub]
- Aphonopelma braunshausenii? No such thing. You can’t make up a whole new species based on the shape of one shed skin. Well, not anymore, at least. [Paper] [Sci-Hub]
- More shakeups in the tarantula taxonomy world. Most interesting here is that one species formerly in the Aphonopelma genus has been found worhty of its own genus, Sandinista! [Paper]
- Your scientists were too busy figuring out how South America’s 34 species of cellar spiders are related to each other that you never bothered to ask yourself what the female of Mesabolivar guapiara even looks like. Well, finally someone got on that. [Paper] [Sci-Hub]
- When the abstract calls a taxonomic family “chaotic”, you know things are gonna change. Several genuses of Asian arboreal tarantulas (Lampropelma, Omothymus, and Phormingochilus) have been rearranged, combined, and added to. Relevant to tarantula-keepers: Lampropelma nigerrimum arboricola, commonly called the “Borneo black tarantula”, is now Phormingochilus arboricola. [Paper]
- Ami is a genus of South American dwarf tarantulas — some are even bred as pets. But it turns out that the genus had already been described in 1925 under the name Neischnocolus, and has now been renamed to that. [Paper]
- Filistata is a genus of crevice weavers, previously thought to have 26 species. A new study has combined some of those and discovered 3 more, leaving a total of 11. Also, the southern house spider Kukulcania hibernalis, normally a New World gal, has been found in the Canary Islands and Liberia.[Paper]
Mites
- A new oribatid from the sandy beaches of Hokkaido (before you start thinking this sounds like a fun field trip, this was in January). [Paper] [Sci-Hub]
- A new soil and leaf litter-dwelling oribatid from Mexico. [Paper] [Sci-Hub]
- Three new soil-dwelling oribatids from Chile. [Paper] [Sci-Hub]
- A new mite from Mercury…Islands, New Zealand. [Paper] [Sci-Hub]
- Two new phytoseiid mites from the Cook Islands. [Paper] [Sci-Hub]
- A new laelapid mite from Slovakia (this one lives in ant nests). [Paper] [Sci-Hub]
- Fossil mite! This mite found in Cretaceous amber from Myanmar is the earliest record of the family Caeculidae. [Paper] [Sci-Hub]
Other Arachnids
- Three new species of Microcharmus scorpions from Madagascar. [Paper]
- Researchers in Iran have confirmed that male and female Rhagodes eylandti camel spiders look so different, they were classified as separate species for years! This species, they say, is common in dry regions across Iran, Afghanistan, and Turkmenistan. [Paper] [Sci-Hub]
- A possibly new species of the opilionid Leiobunum, known only as Leiobunum sp. A, has been spreading across Europe for the past decade. We now have a DNA barcode for it, which can be used to identify this species. [Paper]
Methods
Many arthropod specimens are preserved in ethanol (alcohol), which poses certain difficulties for researchers.
- Ethanol denatures protein, meaning you can’t extract DNA from alcohol-preserved specimens and re-create Jurassic Park. Until now, as these Cambridge, MA researchers have demonstrated with opilionid specimens. [Paper] [Sci-Hub]
- Classifying specimens requires photographing very small body parts under a microscope from certain angles, which can be difficult when working with specimens preserved in liquid. Researchers in Stuttgart, Germany have invented a simple gadget called the Fixator to hold specimens firmly—but safely—in place for photography. [Paper 🔓]
Thanks to Sebastian Alejandro Echeverri and Ivan Magalhaes for their contributions and feedback. Corrections, ideas, and items for next month are welcome! Leave a comment or drop us a (silk) line on Twitter at @arachnofiles.
