Sunday, February 26, 2012

Adventures in Spider Misidentification: Pisaurina, not

Not a Nursery Web Spider
For over three years we have been under the misapprehension that this spider belonged to the family Pisauridae and probably the genus Pisaurina. These 'Nursery Web Spiders' don't make a habit of hanging around nurseries, which I think even arachnophiles may be glad to hear. Instead, their name comes from the small tent-like web they spin when their babies are about to hatch. Before then, they carry the silken ball of eggs with their mouthparts.
Spider eyes tell tales of taxonomic interest
However, today we learned how to use the the Data tab at BugGuide and discovered that no pisaurids were reported from Alberta. This made us a bit suspicious. Also, BugGuide has a very nice diagram of what Pisaurina eyes should look like and this spider does not have the right arrangement. However, the eye arrangement does resemble that of the Slender Crab Spiders (Philodromidae: Tibellus spp.), several of which are known from Alberta.
Philodromus we think
Tibellus currently rests in the family Philodromidae. Actually 'rest' is the wrong word for a Running Crab Spider. Philo-dromus seems to be from the Greek meaning they love to race. Apparently, they like aphids too.
Hot chilli pepper aphid for lunch
We think we see a similarity in the arrangement of the eyes in between what we now think a Tibellus and what we think is a Philodromus rufus (but remember the name of this series). Also, philodromids are supposed to have legs II significantly longer than legs I - and both of these spider do have that character. So, perhaps we are improving in our spider taxonomy. Well, just in case, we've asked the specialists at BugGuide for help this time.
Philodromus looking more floraphillic here, but also more crab spidery

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