Explanation of Names
From Greek philodromos (φιλοδρομος)- "lover of the race/course"
Numbers
Spiders of North America 2nd Edition states that there are 92 species in 6 genera in our region
(1). A 2016 paper added another genus (
Rhysodromus)
(2).
The majority of the species are in the large genus Philodromus.
Identification
Not diagnostic, but some helpful features:(3)
Second pair of legs longer than first
All legs similar in size (Thomisids have back pair smaller than front pair)
Often with a stripe on the back of the head
2 Claws
8 eyes
Flat bodied
Legs laterigrade
Philodromids tend to have the second pair of legs significantly longer than the first pair, which distinguishes them from the similar Thomisid crab spiders. In addition, thomisids have third and fourth legs that are shorter and more slender than the first two pairs of legs, while philodromid legs are subequal in length.
Habitat
Often found on plants (stems & leaves).
Food
These spiders are active predators.
Print References
Schick, R. X. (1965). The crab spiders of California (Araneida, Thomisidae). Bulletin of the AMNH; v. 129, article 1. (
Full Text Here)
Dondale, C. D., & Redner, J. H. (1978). The Crab Spiders of Canada and Alaska (Araneae: Philodromidae and Thomisidae)(The Insects and Arachnids of Canada, Part 5). Agriculture Canada Publication, 1663. (
Full Text Here) - With free account