Acanthogonatus nahuelbuta

Acanthogonatus nahuelbuta is a mygalomorph spider of Chile, named after its type locality: Piedra del Águila, Parque Nacional Nahuel-Buta, Malleco. Males differ from A. patagallina by having the basal portion of the bulb less rounded and the basal loop of the bulbal duct less sinuous; and from those of A. hualpen by the differently shaped embolus and the palpal tibia with the apical two-thirds (instead of its apical one-third) tapering gradually and having thickened setae.

Description

 * Male: total length 13.38 mm; cephalothorax length 5.26 mm, width 3.34 mm; cephalic region length 4.52 mm, width 2.72 mm; medial ocular quadrangle (OQ) length 0.63 mm, width 1.11 mm; fovea width 0.67 mm; labium length 0.51 mm, width 1.03 mm; sternum length 2.97 mm, width 2.44 mm. Its labium possesses no cuspules. A serrula is present. Its sternal sigilla is small, oval and submarginal, while its sternum is strongly rebordered. Chelicerae: rastellum is absent. A small, pallid and protruding cheliceral tumescence is present. Colour as in female.
 * Female: total length 17.54 mm; cephalothorax length 6.19 mm, width 5.29 mm; cephalic region length 4.14 mm, width 3.84 mm; fovea width 0.76 mm; OQ length 0.61 mm, width 1.25 mm; labium length 0.67 mm, width 1.19 mm;sternum length 1.75 mm, width 1.55 mm. Its cephalic region is strongly convex, with a sinuous fovea with short posterior medial notch. Its labium possesses 2 cuspules. A serrula is present. Sternal sigilla is small and oval, while its sternum is rebordered. Chelicerae: rastellum is absent. Its cephalothorax and legs are a reddish-brown colour, while its abdomen is yellowish and densely mottled with dark brown.

Distribution
Provinces of Bío-Bío and Malleco, in Region VIII, Chile.