Acanthogonatus mulchen

Acanthogonatus mulchen is a mygalomorph spider of Chile, named after its type locality: Alto Caledonia, east of Mulchén, Region VIII (Bío Bío Region). It is recognised by the long, narrow sternum. It differs from A. tolhuaca in the spermathecae having a less pronounced notch and the glandular areas on each side joining in the middle. It is larger (A. mulchen has a cephalothorax length of up to 13.2 mm, and a total length of 35.05 mm) and differs from A. brunneus by its uniformly colored abdomen.

Description

 * Female: total length 29.5 mm; cephalothorax length 11.8 mm, width 9.5 mm; cephalic region length 7.7 mm, width 7.5 mm; fovea width 1.5 mm; medial ocular quadrangle length 1 mm, width 1.9 mm; labium length 0.95 mm, width 2 mm; sternum length 6.5 mm, width 4.8 mm. Its cephalic region is wide but low, while its fovea s straight to procurved with recurved ends, containing no posterior notch. Its labium possesses 2 cuspules. A serrula is present as a small patch of teeth only on the anterior face of the lobe. Its sternal sigilla is deep and long. Chelicerae: rastellum is absent. The entire spider is a uniform blackish-reddish-brown colour, except for one lighter spot in front of the abdomen. Juveniles have a similar color, but lighter, with diagonal lines of pale dots on the dorsum of their abdomen.

Distribution
Only in its type locality. It is found in densely silk-lined burrows, between 15 and 20 mm wide, which originate from under stones or at the base of trees. The burrow's mouth is funnel-like, with white silk extending so as to form a sort of collar.