Annotated key to the trematode species infecting Batillaria attramentaria (Prosobranchia: Batillariidae) as first intermediate host

In eastern Asia and western North America at least nine morphologically distinguishable species of digenean trematode infect the mud snail, Batillaria attramentaria (Sowerby 1855) (=B. cumingi (Crosse 1862)), as first intermediate host. Further, molecular and morphological evidence indicates that several of these trematode species comprise complexes of cryptic species. I present an identification key to these nine trematode morphospecies (including four newly reported species). Additionally, I provide an annotated list, which includes further diagnostic information on the larval stages (cercariae, parthenitae, and metacercariae), information on second intermediate host use, links to the previous relevant reports of trematodes infecting B. attramentaria and notes on other aspects of the species' biology.