Alsodes nodosus is a spiny-chest frog occurring in semi-arid portions of central Chile. This Near Threatened insectivore is found in scrub and forest, and its conservation status derives from a limited range. The Black spiny-chest frog is a robust anuran, with adult snout to vent length measuring 50 to 75 millimeters. The dorsum is blackish-olive, with some individuals exhibiting grey or metallic highlights or irregular splotches. The ventrum is rough and spiny, giving rise to the common name of this taxon.