Two new species of the family Mecysmaucheniidae are described: Mecysmauchenius platnicki n. sp., from Malleco, Chile and Mecysmauchenioides quetrihue n. sp., from Neuquén, Argentina, the latter being the second known species of the genus.
Araneae; Mecysmaucheniidae; Mecysmauchenius; Mecysmauchenioides; new species