The chromodond nudibranch Tyrinna nobilis, described originally by Bergh, 1898 from Chile, has been collected on the Atlantic coast of Patagonia (Argentina) We have made a redescription which includes the presence of a vestibular gland, absent in the Bergh's description, and provided information on the biology of the living animals. Tynnna nobilis was compared with other nominal species assigned to the genera Cadlina and Tyrinna. Tynnna pusae Marcus, 1959 was synonymised with T. nobdis, and Cadlina burnayi Ortea, 1988 was included in Tyrinna. The presence of a ramifying vestibular gland in T nobilis, was discussed in relation to phy-logeny of the family Chromodorididae