Background:

Bivalves are part of the fauna that inhabit the coast of the state of Guerrero. Many species are of commer cial importance and few studies exist of this class in the state. The National Commission for the Use and Conservation of Diversity acknowledges the lack of studies regarding the diversity that exists in the Priority Marine Regions (PMRs) located in Guerrero. This study focused on the Bivalves and its

Goals:

were to document species richness by analyzing the composition of the community based on the representation of families, estimate the density, and establish the geo graphical distribution of species.

Methods:

Sampling was conducted at 21 sites, the area was 10 m2 and the unit was 1 m2.

Results:

5962 specimens were analyzed and 40 species were identified. Mytilidae and Arcidae families were the best represented in species richness and Mytilidae and Isognomonidae families were the best represented in abundance. The density was 18.63 organisms / m2 and Choromytilus palliopunctatus (4.5 organisms / m2) and Isognomon janus (4.0 organisms / m2) showed the highest densities. We determined that three species have wide distribution, one species has frequent distribution, eight species have limited distribution, and 32 species have restricted distribution. This study registered five new additions to bivalve fauna in the Mexican Pacific Transition, one for the state of Guerrero, five for PMR 30, six for PmR 31, and 17 for PMR 33.

Conclusions:

Results from this study significantly advance our understanding of biodiversity and ecology of Bivalves in the state of Guerrero.