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Family Philodromidae - Running Crab Spiders

Metallic crab spider - Philodromus marxi

Tibellus duttoni - Tibellus duttoni - female

Gold Metallic Crab Spider - Philodromus marxi

Classification

Kingdom Animalia (Animals)

Phylum Arthropoda (Arthropods)

Subphylum Chelicerata (Chelicerates)

Class Arachnida (Arachnids)

Order Araneae (Spiders)

Infraorder Araneomorphae (True Spiders)

No Taxon (Entelegynae)

Family Philodromidae (Running Crab Spiders)

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.

Range

Widespread

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

Internet References

Species Images

AMNH - Online Key to Genera

World Spider Catalog

iNaturalist

GBIF

Works Cited

1.	Spiders of North America: An Identification Manual, Second Edition Darrell Ubick (Editor), Pierre Paquin (Editor), Paula Cushing (Editor), Nadine Dupérré (Illustrator). 2017. American Arachnological Society.

2.	The spider genus Rhysodromus Schick, 1965 in the Crimea (Aranei: Philodromidae) Kastrygina and Kovblyuk. 2016. Arthropoda Selecta.

3.	Spiders of North America: An Identification Manual D. Ubick, P. Paquin, P.E. Cushing and V. Roth (eds). 2005. American Arachnological Society.

Contributed by Troy Bartlett on 16 February, 2004 - 1:20pm
Additional contributions by Lynette Elliott, Chuck Entz, kschnei, Nathaniel Green, chuuuuung
Last updated 8 April, 2021 - 8:41pm

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