Philodromidae

Running crab spiders
Temporal range:
Philodromus sp.
Running crab spider
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Philodromidae
Thorell, 1870
Diversity
31 genera, 531 species
blue: reported countries (WSC)
green: observation hotspots (iNaturalist)

Philodromidae, also known as philodromid crab spiders and running crab spiders, is a family of araneomorph spiders first described by Tord Tamerlan Teodor Thorell in 1870 (then known as subfamily Philodrominae within Thomisidae).[1] It contains over 500 species in about thirty genera.[2]

The most common genus is Philodromus which is widespread, similar to Ebo.[2] Other common genera include the elongate grass-dwelling Tibellus and the widespread Thanatus, which includes the house crab spider that commonly captures flies on and in buildings.[3]

Description

Philodromids have a crab-like shape due to the first two pairs of legs being oriented sideways (laterigrade).[4] This is superficially similar to the "true" crab spiders (Thomisidae), such as Misumena vatia, but these families are not as closely related as previously thought.[5]

Unlike crab spiders, the legs are generally similar in size, though the second leg pair may be significantly longer than the first pair.[4][5] This is most evident in Ebo, where the second pair of legs are twice as long as the first pair in some species.[5]

Philodromids have scopula only at the tips of the tarsi (unlike sparassids) and the eyes are in two curved rows with the posterior row wider than the anterior row.[4] In terms of colouration, they are usually cream to light brown and have faint longitudinal stripes.[6]

Ecology

Philodromidae are active predators and often occur on the stems and leaves of plants.[7] Some occur only on deciduous trees and others only on conifers.[7] A small number of species live in deserts.[7] Instead of building webs to catch prey, they hunt by ambush.[6]

Genera

As of January 2026, this family includes 31 genera and 531 species:[2]

  • Euthanatus Petrunkevitch, 1950 † (fossil)
  • Filiolella Petrunkevitch, 1955 † (fossil)
  • Medela Petrunkevitch, 1942 † (fossil)

References

  1. ^ Thorell, T. (1870). "On European spiders". Nova Acta Regiae Societatis Scientiarum Upsaliensis. 3 (7): 109–242.
  2. ^ a b c "Family: Philodromidae Thorell, 1869". World Spider Catalog. doi:10.24436/2. Retrieved 2025-10-09.
  3. ^ Kulczyński, W. (1903). "Aranearum et Opilionum species in insula Creta a comite Dre Carolo Attems collectae". Bulletin International de l'Académie des Sciences de Cracovie. 1903: 50.
  4. ^ a b c "araneae - Key to families". araneae.nmbe.ch. Retrieved 2022-07-12.
  5. ^ a b c Homann, H. (1975). "Die Stellung der Thomisidae und der Philodromidae im System der Araneae (Chelicerata, Arachnida)". Zeitschrift für Morphologie der Tiere. 80 (3): 181–202. doi:10.1007/BF00285652. S2CID 2027596.
  6. ^ a b "PHILODROMIDAE Philodromids". www.arachne.org.au. Retrieved 2022-07-12.
  7. ^ a b c "Philodromid Crab Spiders - Encyclopedia of Life". eol.org. Retrieved 2022-07-12.