Bathymodiolinae Mussels in the South-eastern Pacific: the presence of the genus Adipicola (Bivalvia: Mytilidae) at a methane seep site off central Chile

New material collected at a methane seep site off central Chile (36 degrees 21.997 ' S, 73 degrees 42.785 ' W), known as the Concepcion Methane Seep Area (CMSA), revealed the presence of the genus Adipicola in the SE Pacific. Dead individuals consisting of empty single and articulated valves were collected from vesicomyid clam beds, at 690 m depth by the remotely operated vehicle KIEL 6000, using scoop nets. Shell characters, such as equivalve, antero-posteriorly elongate shell, external surface smooth without periostracal hair, not gaped and hinge plate without teeth or crenulations, were observed and compared with the morphology of described species within the genus. Based on these morphological characters we tentatively assign the individuals belonging to Adipicola leticiae previously never found below 27 degrees S in the SE Pacific. This new finding constitutes the first record of an extant Bathymodiolinae mussel off central Chile. The current knowledge of additional chemosymbiotic bivalves at the CMSA is discussed. The present study updates and contributes to the knowledge of deep-water bivalve biodiversity in Chilean waters.