Genus Acanthochitona Gray, 1821

Type species: Chiton fascicularis Linnaeus, 1767, by monotypy.

Diagnosis. Small to large chitons. Tegmentum rather wide to reduced, with usually well defined, but sometimes obsolete, narrow to wedge-shaped jugum; lateral and pleural areas hardly separable. Articulamentum large; sutural laminae weakly concave to convex in antero-lateral edge in tail valve; insertion plates various sizes; slit formula 5/ 1/2. Girdle moderate width to large, fleshy, densely spiculose, usually not completely encroaching between valves; sutural tufts always present, usually prominent. Radula teeth arranged symmetrically; central tooth symmetrical (rarely asymmetrical), narrow to wide, thin to thick; first lateral (centro-lateral) tooth with thickened, nodulous antero-dorsal corner; major lateral tooth with tricuspid head which denticles are nearly equal in length to decidedly longer in median one (radula characters: after Saito 2004 with modification).