The diagnostic characters of the Asterinidae species Asterina atyphoida H.L. Clark from southern Australia and Asterina gibbosa (Pennant) from the Atlantic, type species of Asterina Nardo, are reviewed. Asterina atyphoida is referred to Meridiastra gen. nov., with four other species: Meridiastra fissura sp. nov. and Meridiastra nigranota sp. nov. from southern Australia, Meridiastra rapa sp. nov. from the central south Pacific, and Meridiastra modesta (Verrill) from the Pacific coast of Panama and Mexico. Asterina agustincasoi Caso is synonymised with Meridiastra modesta (Verrill). Asterinides Verrill is recognised as a valid genus. Meridiastra fissura is fissiparous. Meridiastra is distributed from southern Australia to the Pacific coast of Mexico and Panama. A key is provided for the species of Meridiastra.