Thin section study of Upper Turonian to Senonian biomicrites, bio-intramicrites and intra-biomicrorudites of the Penitell nappe in eastern Algeria has allowed to describe a new species of Dinoflagellata calcareous cyst with a two-layer, structurally inhomogeneous wall. In the submitted work the new cyst, assigned into the subfamily Pithonelloideae KEUPP, 1987, has been denominated Pithonella siniformis n. sp.