Distribution of the introduced crab spider Ozyptila praticola (C. L. Koch, 1837) (Araneae: Thomisidae) in the Puget Lowlands of Washington, U.S.A.

Since its introduction into Seattle, King County, Washington, prior to 1952, the European thomisid Ozyptila praticola (C. L. Koch, 1837) has spread throughout the eastern Puget Lowlands to inhabit an area of over 1300 sq mi (3400 sq km) centered in western King and Snohomish Counties. A separate population of O. praticola was also found in western Whatcom Co. that may be linked to the O. praticola population in Metro Vancouver, British Columbia, Canada. Ozyptila praticola was eudominant (> 10% abundance) in 86% of fallen conifer cone, 69% of moss, and 55% of litter samples. It was largely found in anthropogenically disturbed habitats, with some invasion into forests adjacent to development. Females, penultimates, and a consistent size-range of pre-penultimate juveniles were present year-round. Males were found mainly in spring and fall. Ozyptila praticola may be expected to continue increasing its range in anthropogenic and adjacent habitats in western Washington. [ABSTRACT FROM AUTHOR]