It probably does little to assuage the unsavory first impressions one has with the subject of the third group featured in this blog’s arachnid series, the pseudoscorpion, by noting that its name literally means “false scorpion.” Perhaps this is no surprise, given that without the proper context, pseudoscorpions are intimidating both in their name and in their generally “icky” appearance, armed with menacing claws, attached to a body that resembles a lightbulb made out of alligator skin. If nothing else, you’d at least be somewhat justified in being suspicious of them. Looks like a scorpion, has “scorpion” right in the name, but isn’t a real scorpion? Please. Just what is that tailless son of a bitch hiding? Maybe you doubt that there is such an animal, and the photo above simply depicts a normal scorpion, sans its stinging tail, removed by Photoshop. “What kind of rube do you take me for, blogger on the Internet?! I do not take kindly to unprovoked trickery!”, you howl, with language curiously more sophisticated than what is normal for someone so enraged.
The thing is, pseudoscorpions really are a unique group of arachnids distinct from “true scorpions.” They are partitioned off from the rest of the arachnids in their own taxonomic order, the predictably-named Pseudoscorpionida (also called Chelonethida). It is thought that in the Great Arachnid Family Tree, pseudoscorpions represent one of several springy arms forking off from a massive branch known as Dromopoda, which also includes potential sister groups like harvestmen (think daddy longlegs), “actual” scorpions (the nasty, pinchy, venomous kind), and solifugids (the infamous “camel spiders” of Internet renown, the subject of urban legends stemming from U.S. soldiers’ alleged interactions with them during the Iraq War…and a tasty snack for Bear Grylls). There is some disagreement within the scientific community about the Dromopoda division, and whether or not it is a true, monophyletic group (monophyletic meaning that it’s a defined grouping on a tree including a species and all of its descendants; for example, the grouping of “reptiles” excludes mammals and birds, and would exhibit something known as paraphyly…however “amniotes” includes ALL the descendants of the amniote common ancestor (birds, lizards, mammals, snakes, turtles, etc.) and would constitute a legitimate, monophyletic taxon), but even if Dromopoda isn’t a cohesive evolutionary unit, it is still likely that pseudoscorpions, based on a combination of morphological and molecular characters, are closely allied, evolutionarily, with many of those “Dromopodan” orders. So yes, pseudoscorpions are kissing cousins with desert-terrorizing nightmares like scorpions and camel spiders, and those gangly, spider-lookin’ things that collect as corpses in the lonely corners of your garage every summer.