A new research article just published today describes a new genus and species of spider from caves in the Pacific northwest named Trogloraptor marchingtoni. Besides the amazing name this wonderful non-insect arthropod has been given, it’s also extraordinary because the authors have determined that this spider actually belongs in a completely new family! The new family name? Trogloraptoridae, of course. This is a pretty big deal – it’s not everyday that a new spider family is described!
So, where does this new family belong in relation to other spider families (i.e. what other families are Trogloraptoridae closely related to phylogenetically)? Let’s see if someone with limited knowledge of spider morphology can describe this. Well, the pedipalpal bulb of the male has two parts fused together, which apparently places it with other spiders in the group Haplogynae. For those of you that don’t know, the pedipalpal bulb of males is used to transfer sperm to females during mating, which I think is fascinating.
Here’s an image of a mature male Trogloraptor‘s beautiful pedipalp, which immediately reminded me of little
Sally Cindy Lou Who from Whoville and her holiday ornament…
Additionally, some of the spinnerets have a line of membranous cuticle that cuts across diagonally amidst other sclerotized regions (see image below). This character isn’t present in other spider families of the Haplogyne, so Trogloraptoridae is most likely related to those spiders that have this diagonal as well, which places it in the Dysderoidea. The authors suggest that Trogloraptoridae may be a primitive member of this spider clade. A more detailed phylogenetic analysis will have to be performed to test this hypothesis.
One of the most interesting things about this article is that this spider is actually not that small, roughly between 7 and 10 mm. It just appears to spend it’s time hanging out in caves and is probably why no one had discovered it until now. I think it’s amazing that there are not only new species and genera to be described from our backyard, but even new families!
Griswold CE, Audisio T, Ledford JM (2012) An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family). ZooKeys 215: 77–102. doi: 10.3897/zookeys.215.3547