Pseudoscorpionida

(invertebrate zoology) An order of terrestrial Arachnida having the general appearance of miniature scorpions without the postabdomen and sting.

An order of terrestrial Arachnida having the general appearance of miniature scorpions without the postabdomen and sting. The body length is seldom greater than 0.2 in. (5.0 mm). Typically, each finger of the anterior appendages, or chelicerae, has a serrula composed of a row of ligulate plates. Ducts of silk glands open near the end of the movable finger, often in connection with a simple or branched spinneret. The second pair of appendages, or palpi, are large and conspicuous, usually with glands that discharge venom through a terminal tooth on one or both of the chelal fingers. The four pairs of legs are ambulatory.

Pseudoscorpions feed chiefly on small arthropods and, although frequently found on birds, mammals, and insects, are considered nonparasitic. Pseudoscorpions are common in the nests of mammals, birds, and social insects, in woody debris and forest litter, under stones, and in crevices in the bark of trees. About 2000 species have been described. See also Arachnida.