What do we know about the marine bivalve fauna in western South America?

VALENTICH-SCOTT P., E. V. COAN Y D. G. ZELAYA

Michigan

Congreso; American Malacological Society 81st Annual Meeting; 2015

Bivalve Seashells of Western South America is the third in a series of monographs on the eastern Pacific Ocean marine bivalve fauna. The scope of this monograph is the fauna from the Perú-Chile Province, an area that extends from Punta Aguja, Piura, Perú (5.8°S), and continues south to the southern tip of Isla Chiloé, Los Lagos, Chile (43.4°S), considering the species occurring from the intertidal zone to the deep sea. We do not include the Chilean possession of Isla de Pascua [Easter Island], which is very distant from the continent and has an altogether different and unique fauna. Through a literature review and direct examination of specimens inmuseum and university collections, a marked decrease in known bivalve diversity has been observed when comparing the fauna from the Perú-Chile Province with similar northern latitudes. In the Alaskan, Oregonian and Californian Provinces, we have documented over 470 bivalve species, and 892 species in the Panamic Province, whereas we currently only have records for 201 verified named species from the Perú-Chile Province. In addition we have isolated an additional 38 marine bivalve species that are potentially new to science in the Perú-Chile Province, along with another 26 species which might range into the northern or southern limits of the Province. If the potentially new species and marginally ranged species are included, we would still have only 265 species in the region, some 45% less than thetemperate regions in the northern Pacific. One factor that could help to understand the observed decrease in the number of species present in the southeastern Pacific may be under-sampling, especially in deeper waters. This fact is clearly evidenced when considering the high number of new species discovered in the study area. In addition, a very narrow continental shelf throughout much of the Province affords fewer shelf habitats, and may also be leading to a much lower bivalve diversity.