Jp. Barry et Re. Kochevar, Calyptogena diagonalis, a new vesicomyid bivalve from subduction zone coldseeps in the eastern North Pacific, VELIGER, 42(2), 1999, pp. 117-123
A new vesicomyid bivalve species, Calyptogena diagonalis, is described from
cold seep communities in the Cascadia subduction zone off the Oregon coast
and accretionary wedge sediments along the Pacific coast of Costa Rica. Li
ve bivalves and shells were collected at sulfide seeps near 2021 m depth in
Oregon and from 2900 to 3800 m depth in Costa Rica. Shell morphology of C.
diagonalis differs considerably from sympatric congeneric and confamilial
species of the northeastern Pacific. Shells are large (to 24.0 cm) and elon
gate (H/L = 0.42), with one or more ridges on the external shell surface ex
tending diagonally from the umbo to near the posteroventral margin. Enlarge
d, sulfur-colored ctenidia and micrographs of endosymbiotic bacteria held i
n ctenidia suggest that this species, like other vesicomyids, is a sulfur-b
ased chemolithoautotroph.