Marine bivalves zoogeography in the Tamaulipas coast, Mexico

This study provides both a current taxonomic listing of known species of marine bivalves from the coast of Tamaulipas, Mexico as well as an overall assessment of their poorly known biogeographical relationships. Marine bivalves were surveyed (midlittoral, supralitoral and sublittoral zones) from September 1987 to April 2010. One hundred and thirty-one species of marine bivalves representing 98 genera in 37 families are reported. Two species are first records for Tamaulipas. These 131 species share the following malacogeographical relationships: 62 species (47.32%) exhibit Caribbean and Carolinian affinities, 20 species (15.26%) exhibit Carolinian and Caribbean affinities, 13 species (9.92%) exhibit Carolinian and Argentinean affinities and 12 species (9.16%) exhibit Caribbean, Carolinian and Boreal affinities. Only 6 species (4.58%) exhibit an exclusive Caribbean distribution and 4 species (3.05%) are known only from the Gulf of Mexico. The fact that 81.66% (107 species) of the marine Tamaulipan bivalve fauna exhibits the above malacogeographical relationships provides overwhelming evidence that the Tamaulipan coast of Mexico represents a transitional zone between the Carolinian and Caribbean malacological provinces.