Echyridella onekaka is a species of freshwater mussel endemic to New Zealand. E. onekaka is an aquatic bivalve mollusc in the family Unionidae, the river mussels.
The species was first recognised as a distinct species by Mark Fenwick and Bruce Marshall in 2006. It can be distinguished from Echyridella menziesii by a more strongly separated anterior pedal retractor muscle.
Echyridella onekaka is found exclusively in the north-west of the South Island.[1] It is the rarest known freshwater mussel species in New Zealand.[2]