Atagema notacristata is a species of sea slug or dorid nudibranch, a marine gastropod mollusc in the family Discodorididae.[1]
The holotype for this species was collected from Punta Uvita, Parque Nacional Marino Ballena, Area de Conservación Osa, Costa Rica (9.1472°N -83.7711°W). Numerous specimens from Costa Rica were included in the original description. Further records from Bahía de Banderas, Mexico and Coiba Island, Panama, were also reported.