Philodromus infuscatus

Keyserling, 1880

Running crab spider

Species Guides

1

Philodromus infuscatus is a running crab spider in the Philodromidae, part of the infuscatus group comprising 20 species and 2 . The species is divided into two subspecies: P. i. infuscatus in the eastern United States and P. i. utus Chamberlin in the western United States. It is the only member of its species group to reach Canada. These spiders are active hunters that do not build webs to capture prey.

Pronunciation

How to pronounce Philodromus infuscatus: /fɪloʊˈdroʊməs ɪnˌfjʊˈskeɪtəs/

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Identification

Philodromus infuscatus belongs to the infuscatus group, which can be distinguished from other Philodromus groups by morphological features detailed in taxonomic revisions. The P. i. infuscatus (eastern) and P. i. utus (western) are separated by geographic distribution. As a running crab spider, it has laterigrade legs oriented horizontally for sideways movement, and the second pair of legs is the longest. The has a flattened body adapted for hiding in narrow crevices.

Habitat

Dry parts of the United States and Mexico. The occupies xeric and semi-arid environments characteristic of the infuscatus group.

Distribution

Eastern United States ( P. i. infuscatus), western United States (subspecies P. i. utus), and Canada—the only in the infuscatus group with a range extending into Canada.

Behavior

Running crab spiders are active hunters that do not construct webs for prey capture. They rely on speed and ambush to capture prey.

Similar Taxa

  • Philodromus disparThe sole American representative of the dispar group, introduced from the Old World; can be distinguished by group-level morphological characteristics
  • Philodromus droseroidesAnother member of the infuscatus group with similar preferences; divided into P. d. droseroides (California) and P. d. arizonensis (Arizona)

More Details

Taxonomic revision

The infuscatus group was comprehensively revised in 1969 (The Canadian Entomologist 101: 921-925), which described numerous new and clarified boundaries within P. infuscatus and P. droseroides.

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