Registro actual de especies del genero Musculium Link, 1807 (Bivalvia: Sphaeriidae) en Chile con notas sobre morfologia y biometria de sus poblaciones

This study reports the present distribution range of Musculium argentinum (D'Orbigny, 1835) and Musculium patagonicum Pilsbry, 1911 in Chile, from sampling data carried out from 2002 to 2006. Morphological and biometric characteristies of the studied populations show that M. argentinum is discontinually distributed between 38°S-41°S and 71°W-72°W, inhabiting fluvial and lacustrine waters. M. patagonicum was reported in a lentic environment. (51°42'S; 72°25'W). Both species are morphologically very similar. M. argentinum differs from M. patagonicum because de first has their valves more markedly cuadrangular or trapezoidal with the posterior end slightly truncated, upper dorsal extremes markedly cuadrangular, hinge plate less solid, nearly straight or weakly curved. Constant hinge length-shell length ratio. The shell outline of M. patagonicum is not as markedly trapezoidal as in M. argentinum. In the first, the posterior margin is less abrutptly truncated, and the shell outline not sharp-cornered as is typical for M. argentinum. The hinge plate in M. patagonicum is always weakly curved never straight or broken as in M. argentinum. The collected material is deposited at the Zoological Collection of the Catholic University of Temuco and in the Malacological Section of the Nacional Museum of Natural History, Chile