A PRIMITIVE HALOBIA (BIVALVIA: HALOBIOIDEA) FROM THE TRIASSIC OF NORTHEAST BRITISH COLUMBIA

ABSTRACT—Halobia daonellaformis new species is described from the lowermost Carnian of northeast British Columbia. Halobia daonellaformis n. sp. is regarded as a primitive Halobia characterized by external ornamentation similar to Daonella lommeli, but with a poorly developed anterior auricle. Morphologic characters of H. daonellaformis n. sp. suggest that Halobia may be not a natural taxon but a polyphyletic group with one or more ancestors from Daonella and Aparimella and/or other posidoniid(s). The sudden appearance of Halobia throughout the marine Triassic suggests a rapid dispersal mechanism following a Ladinian origin. Larval shell morphology indicates a planktotrophic developmental strategy for H. daonellaformis n. sp., and by extension to other halobiids, which may explain the widespread distribution of many halobiid species