Shell shape variation in the freshwater bivalve Diplodon chilensis (Bivalve, Hyriidae) from habitats with different hydrological conditions.

YUSSEPPONE MS; MÁRQUEZ F; LUQUET C.M; RIOS DE MOLINA MC; ROCCHETTA I.

Cambridge

Congreso; European Malacological Congress 2014. 7th Congress of the European Malacological Societies; 2014

European Malacological Societies

The freshwater mussel Diplodon chilensis (Gray, 1828) is one of the most abundant benthic species both in lentic and lotic Patagonian environments. Different hydrological conditions can produce shell-shape changes with a high inter and intra-population morphological variability. In this study, we analyzed the ontogenetic allometry and shell shapes variation from two different populations of D. chilensis, obtained from a lake and a river, by using geometric morphometric tools. The samples were collected by SCUBA diving at two sites in the North Patagonian region, Neuquén province (Argentina), Paimún lake (39°44.78?S 71°37.48?W) and Chimehuín river (39º54? 57.15??S 71º06?23??W). Internal shell growth bands of 77 right valves of D. chilensis from each site were counted to estimate the individual age and the left valves were used to morphometric analysis by using 10 landmarks and 30 semi-landmarks techniques. The age range analyzed was from 1 to 118 in Paimún lake and from 2 to 59 years old in Chimehuín river. The multivariate regression of shape on logarithm of the age (ln age) was significant however it was not the main source of morphological variations (only a 5.98% explained). Despite the different life styles between younger and older bivalves related to the borrowing ability, we found that the shell shape seems to be preserved over the life. Contrary, we found shell shape differences (p