difference between cypraea zebra and cervinetta

[paul monfils]

Hi Chris,
Welcome to the site. Both pairs of species you mentioned have to be separated on fairly fine points when working from the shell alone.

C. zebra, as compared to C. cervinetta, is relatively more plump and more cylindrical. Which is to say that C. cervinetta is relatively more elongate (has a higher length-to-width ratio) and relatively more depressed (dorso-ventrally flattened). The apertures of both species widen anteriorly, but more so in C. cervinetta. In C. zebra the anterior aperture is about twice as wide as the posterior aperture; in C. cernivetta about three times as wide. In C. zebra many of the spots low on the lateral margins, where the dorsum meets the base of the shell, are ocellated, that is the white spots have dark centers so they look like "rings". In C. cervinetta all or most of the spots on the lateral margins are solid white, though I have seen specimens with a few lightly ocellated spots mixed in. Using these criteria I would estimate that 90% of specimens can be identified with certainty quite easily, but there may be 10% that are more ambiguous. Of course if you have reliable locality data this will help since C. zebra is Atlantic/Caribbean while C. cervinetta is Pacific.

The carneola/leviathan question offers us less to work with. Locality data won't help since C. carneola is found everywhere that C. leviathan is found. The mantles of the two species are quite distinct, however that doesn't help when we have only the shell to work with. C. leviathan grows considerably larger than C. carneola. C. carneola seldom exceeds 50 mm and almost never exceeds 60 mm. C. leviathan often exceeds 70 mm and sometimes exceeds 100 mm. When C. leviathan reach a large size the lateral margins begin to develop raised smooth tubercles (bumps). Therefore a shell larger than 60 mm with tuberculate margins is almost surely C. leviathan. However, a small, young C. leviathan which has not yet developed such tubercles cannot reliably be separated from C. carneola by shell characteristics alone.