Atagema notacristata is a species of sea slug or dorid nudibranch, a marine gastropod mollusc in the family Discodorididae.

[2] The holotype for this species was collected from Punta Uvita, Parque Nacional Marino Ballena, Area de Conservación Osa, Costa Rica (9°08′50″N 83°46′16″W / 9.14722°N 83.77111°W / 9.14722; -83.77111).

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.