Gastropoda - Epitonioidea - Epitoniidae
Alternative spellings: Hemiacirsa, Scalaria (Hemiacirsa)
Parent taxon: Acirsa according to T. Kase 1984
See also Darragh 2017, Palmer and Brann 1966 and Sepkoski 2002
Sister taxa: Acirsa (Acirsa), Acirsa (Acirsella), Acirsa (Plesioacirsa), Acirsa alpha, Acirsa beta, Acirsa culmosa, Acirsa delta, Acirsa epsilon, Acirsa gravida, Acirsa nexilia, Acirsa obtusa, Acirsa penepolaris
Subtaxa: Acirsa (Hemiacirsa) americana Acirsa (Hemiacirsa) gracilior Acirsa (Hemiacirsa) whitneyi
Ecology: slow-moving low-level epifaunal carnivore
Distribution:
• Quaternary of Italy (1 collection)
• Miocene of Denmark (1), Germany (13), the Netherlands (1), Poland (1)
• Eocene of United States (8: Alabama, Louisiana, Texas)
• Paleocene of Denmark (4), Greenland (2), United States (1: Texas)
• Cretaceous of Germany (2), Japan (3), United States (11: Alabama, Georgia, Maryland, North Carolina, Tennessee, Texas)
Total: 48 collections including 50 occurrences