THE PREY OF A LITHOPHILOUS CRAB SPIDER XYSTICUS LOEFFLERI (ARANEAE, THOMISIDAE)

The natural prey of the crab spider Xysticus loeffleri Roewer 1955, living under stones, was studied. The percentage of feeding specimens in the population studied was low (1.4–4.6%), and it declined with the beginning of the breeding period. Investigation has shown that X. loeffleri is a polyphagous predator. Representatives of twelve arthropod orders were found in its diet. Arachnids (opilionids and spiders) formed the major food component constituting ca. 70% of prey captured. No insect order was present in any considerable percentage. Several worker ants were observed as prey suggesting that X. loeffleri is a myrmecophagic spider. Seven incidences of cannibalism were recorded, which all involved predation on adult conspecifics (two males and five females). The length of prey killed by X. loeffleri ranged between 1.25 and 15.00 mm (mean 4.68 mm) and constituted from 14.3–187.5% (mean 64.2%) of length of their captors. The most frequently captured prey were small arthropods not exceeding half the size of the spiders.