Psilochorus

Simon, 1893

Psilochorus is a of cellar (Pholcidae) established by Simon in 1893. The genus is characterized by a humped, oval and eight arranged in two rows. Most occur in the New World, particularly Mexico and the United States, though P. simoni has been to Europe. Members build webs and exhibit a distinctive anti- defense called whirling, where the spider rotates rapidly while remaining anchored to .

Psilochorus rockefelleri by (c) Jared Shorma, some rights reserved (CC BY), uploaded by Jared Shorma. Used under a CC-BY license.

Psilochorus utahensis by (c) Jason Eckberg, some rights reserved (CC BY), uploaded by Jason Eckberg. Used under a CC-BY license.

Psilochorus simoni by (c) Lek Khauv, some rights reserved (CC BY), uploaded by Lek Khauv. Used under a CC-BY license.

Pronunciation

How to pronounce Psilochorus: /ˈsɪloʊkɔːrəs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Pholcidae by the combination of a humped, oval and the two-rowed arrangement. The name derives from Greek psilos ('naked') combined with a second element possibly meaning 'dance' or 'separate'.

Images

Habitat

vary by . P. inyo occurs in xeric desert environments under rocks in dry washes with creosote bush and desert almond. P. simoni has been found in caves and habitats in Europe. Tropical species such as P. sphaeroides build webs in vegetation.

Distribution

Primarily New World distribution, with most described from Mexico and the United States. Additional species occur in South America (Brazil, Ecuador). P. simoni is to subtropical America but has been to Europe, where it has been recorded from Slovenia, Denmark, Norway, and Sweden. P. nigromaculatus was described from New Guinea but is considered misplaced.

Behavior

Exhibits whirling as an anti- defense: when disturbed, the rotates its body rapidly in circles while legs remain anchored to the web. This is elicited primarily by tactile stimuli and air movement, not chemical cues. Whirling is effective against web-invading predators such as (Salticidae), including Portia and Euryattus. Artificially induced whirling prevents successful entirely.

Similar Taxa

PholcusAlso Pholcidae with long legs, but lacks the humped characteristic of Psilochorus; P. phalangioides exhibits whirling but with different stimulus thresholds.
SmeringopusAnother pholcid that exhibits whirling defense ; distinguished by morphological differences in shape and arrangement.

More Details

Etymology

The name combines Greek psilos ('naked') with a second element of uncertain derivation, possibly from a word for 'dance' or 'separate'.

Species diversity

The contains approximately 40 described , with the majority described by Gertsch and Chamberlin in the mid-20th century.