Background:

Marine gastropods and bivalves are some of the most diverse invertebrate groups in nature, but in Mexico a better knowledge of their taxonomic composition is required. Although there are important studies on mollusks in the Mexican Caribbean, some areas such as island of Cozumel have been barely studied.

Goals:

To reveal new records of island of Cozumel marine gastropods and bivalves. Methods: The specimens were collected mainly from transects in sandy substrates and revision of rocky surfaces.

Results:

Out of a total of 51 species of gastropods belonging to 39 genera and 23 families, and 11 species of bivalves belonging to 10 genera and nine families, nine species were registered as new records, six of gastropods and three of bivalves, which increases knowledge of the marine malacofauna of the region. The new records represent 11.76% and 27.27, respectively, of the total fauna of gastropods and marine bivalves known on the coasts of the island of Cozumel. The main malacogeographic affinity of the new records is the Caribbean.

Conclusions:

The study area has a 87.93% of the known marine gastropods for the state of Quintana Roo. The total marine bivalve species in the study area constitute 13.92% of the fauna of this mollusk class for the state. Although the main malacogeographic affinity of the new marine mollusk records is the Caribbean, the study area belongs to a transition zone with the Carolinean province. None of the new records is endemic. All the gastropod and bivalve species indicated as new records can be found in at least four malacological subprovinces.