A new pourtalesiid echinoid Rictocystis jensenae g. et sp. n. is found in low-latitude region of the Indian Ocean and the western Pacific at the depths of 3070-4920 m. The new genus is morphologically similar to Helgocystis and Echinosigra and differs from them by the unique combination of primitive and specialized characters. The only species of Helgocystis, H. carinata, is redescribed according to the specimens from the South Sandwich Trench in the Antarctic. Rictocystis and Echinosigra have the same morphological adaptations to burrowing which are the result of convergent evolution.