Marionia elongoreticulata is a species of sea slug, a dendronotid nudibranch, a marine gastropod mollusc in the family Tritoniidae.[1]
This species was described from North Najata (Nyata) Island, Banda Sea, -7.5091°N 127.2901°W, Indonesia with additional specimens from Culebra Island in the Verde Island Passage, Philippines, 13.6302°N 120.9473°W. It has been reported from Pulau Sangeang, -8.1828°N 118.9866°W, Indonesia.[2]