The spider family Philodromidae (running crab spiders) includes 542 described species, nearly a hundred of which are known from North America north of Mexico (Philodromus dispar is native to Europe and Central Asia, but has been introduced to the United States and Canada) (Platnick 2013).
Philodromids are two-clawed, flat-bodied, somewhat crab-like hunting spiders (Dondale 2005). Like thomisids, many species hold their legs in a laterigrade position (i.e., the legs extend sidewise and the femora, especially, are twisted so that the front surface faces up). The eight eyes are at the front of a narrow cephalic region (i.e., the forward part, or "head" region, of the cephalothorax) and the cephalothorax is broad and often as wide as it is long. These spiders were formerly considered to comprise a subfamily of Thomisidae, but Homann (1975, cited in Dondale 2005) concluded that they were independent of the thomisids, a finding confirmed by the molecular phylogenetic analysis by Benjamin et al. (2008). In comparison with philodromids, thomisids tend to have more compact and globose bodies, with thicker legs; raptorial spines on the first pair of legs; prominent eye tubercles ("bumps"); and no claw tufts or scopulae, or distinct brushes of hair, on their legs.
Philodromids lead an active predatory lifestyle on plant stems and leaves. Some are found only on coniferous trees, others only on deciduous trees; a small number live in deserts. Life histories have been studied by Dondale (1961) and Putnam (1967) and Haynes and Sisojevic (1966) studied predatory behavior. Dondale (1964, 1967) used courtship behavior to distinguish some closely related species.
(Dondale 2005; Bradley 2013)
Philodromidae Thorell, 1870
Philodromidae Thorell, 1870
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:1863
Specimens with Barcodes:1842
Species With Barcodes:67
However, studies have shown that these families are not as closely related as previously thought. Unlike thomisids, philodromids tend to have few true setae (hairs or spines) on their bodies. They also lack the congruent eye tubercles of some thomisids. The second legs are usually the longer of the four pairs of walking legs and in the genus Ebo this is quite extreme, with the second pair of legs in some species twice as long as the first pair.
The most common genus is Philodromus which, like Ebo is widespread. Other common genera include the elongate grass-dwelling Tibellus and the widespread Thanatus, which includes the widely distributed Holarctic house crab spider Thanatus vulgaris. This species commonly captures flies on and in buildings.
The family contains over 500 species in nearly 30 genera. Most are dull colored- brown, gray, yellowish or mottled, and seldom reach above 10 mm in body length. Most have a leaf-like cardiac mark on the anterior dorsal abdomen. None of the species build webs, but they do use silk for draglines and for egg sacs.
The categorization into subfamilies follows Joel Hallan's Biology Catalog.
- Apollophanes O. P-Cambridge, 1898 (USA to Panama, India, Russia, Korea)
- Bacillocnemis Mello-Leitão, 1938 (Argentina)
- Berlandiella Mello-Leitão, 1929 (Brazil)
- Cleocnemis Simon, 1886 (South America)
- Ebo Keyserling, 1884 (Argentina, North America, India, Russia, Israel)
- Eminella Özdikmen, 2007 (Argentina) - renamed from Catuna Mello-Leitão, 1940
- Fageia Mello-Leitão, 1929 (Brazil)
- Gephyrellula Strand, 1932 (Brazil)
- Gephyrina Simon, 1895 (South America)
- Gephyrota Strand, 1932 (Africa, Asia)
- Hirriusa Strand, 1932 (Africa)
- Metacleocnemis Mello-Leitão, 1929 (Brazil)
- Paracleocnemis Schiapelli & Gerschman, 1942 (Argentina)
- Paratibellus Simon, 1932 (Europe to Central Asia)
- Petrichus Simon, 1886 (South America)
- Philodromops Mello-Leitão, 1943 (Brazil)
- Philodromus Walckenaer, 1826 (236 species; Holarctic, America, Australia, Africa, southern Asia)
- Procleocnemis Mello-Leitão, 1929 (Brazil)
- Suemus Simon, 1895 (Africa, Vietnam)
- Thanatus C. L. Koch, 1837 (Africa, Holarctic, South America)
- Tibellus Simon, 1875 (Africa, America, Holarctic, southern Asia)
- Tibitanus Simon, 1907 (Africa)
- Vacchellia Caporiacco, 1935 (Karakorum)
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