First elucidation of a didymozoid life cycle: Saccularina magnacetabula n. gen. n. sp. infecting an arcid bivalve

•Sporocysts from a bivalve genetically matched a didymozoid from Elops hawaiensis.•The life cycle of this new species and genus is the first known for any didymozoid.•This species is the first identified hemiuroid using a bivalve as asexual host.•Host-switching and speciation might explain the use of a bivalve by this species.