Xysticus audax

The specific name audax is derived from the Latin word meaning "bold" or "daring" (German: verwegen), referring to the spider's behavior as observed by the original describer.^[3]

Xysticus audax exhibits considerable variation in coloration and pattern, making identification challenging, particularly for females.^[1][2]

As with crab spiders in general, females are larger than males, with a total length of 4.3–6.4 mm and cephalothorax length of 1.88–2.93 mm. Two main color varieties have been documented: a dark variety and a light variety. The dark variety has sides of the cephalothorax that are dark brown with yellowish dots and spots, while the light variety shows pale brown coloration with darker patches.^[2]

The epigyne is highly variable and features an atrium divided by a broad septum that is usually broader than in X. cristatus. The anterior borders each bear a low but distinct tooth, and the copulatory ducts vary considerably in length.^[2]

Males have a total length of 3.8–5.0 mm, with the cephalothorax measuring 1.97–2.91 mm in length and 1.88–2.59 mm in width. The cephalothorax is brown to dark brown with a median band that is brownish anteriorly and becomes yellowish-white posteriorly. The chelicerae are dark greyish-brown with a yellowish-white diagonal band, while the sternum is yellowish-white with black dots.^[2]

The legs show a distinctive pattern with distal segments mostly pale yellowish-brown and proximal segments dark brown with yellow-white dots and patches. The opisthosoma is dark brown with a whitish, distinctly dentated median band and dull yellowish-white margins.^[2]

Males can be distinguished from the closely related Xysticus cristatus by specific characteristics of the pedipalp. The median apophysis has a pickaxe shape with short shaft ends that are nearly equal in length, and the longest tooth of the basal tegular apophysis is distinctive.^[1]

X. audax is a trans-Eurasian temperate species with a broad distribution across the Palearctic region. It ranges from Iceland in the west through the temperate belt of Eurasia to Sakhalin and Japan (Hokkaido and Honshu) in the east.^[1] The species has been recorded from numerous countries including Russia, Kazakhstan, Iran, China, Korea, and most European countries.^[4]

Some records from Crete, Turkey, and Iran may require confirmation and could potentially represent misidentifications of related species.^[1]

The species inhabits a variety of open and semi-open habitats including meadows, groves, heathlands with Calluna, and dry pine forests.^[2] It has been collected from various vegetation types including steppe slopes, mixed forests, and tundra environments.^[1]