A new species of cuttlefish Sepia shazae n. sp. is described from South Africa. It is one of the commonest small Sepia species in South African waters occurring from 29°48'S in the north to 25°E in the east, between 200 and 700 m (only the third Sepia species recorded deeper than 600 m). It is recognised by: four papillae clusters dorsally on the head between the eyes; tubercles, warts and prominent clusters dorsally on mantle; skin between these structures smooth and shiny; cuttlebone lightly calcified, thin and fragile with thin inner cone and broad outer cone. S. shazae has been confused with Sepia dubia Adam et Rees, 1966 and is well represented in the holdings of the Iziko Museum, Cape Town (SAMC) as “S. dubia(?)”. S. dubia is re-described here on the basis of the second known individual, and is recognised by: four turret-clusters on dorsal head; two turrets transversely on mid-dorsal mantle; small warts covering dorsal body; cuttlebone heavily calcified, exceptionally broad, especially posterior phragmocone and outer cone. The holotype of S. shazae is deposited in the South African Institute of Aquatic Biodiversity (SAIAB) and paratypes in SAMC and the Natural History Museum (NHMUK), London. The new individual of S. dubia is deposited in SAIAB (the holotype is housed in NHMUK).