Monostroma quaternarium
- kingdom: Plantae
- phylum: Chlorophyta
- class: Ulvophyceae
- order: Ulotrichales
- family: Gomontiaceae
- genus: Monostroma
- species: Monostroma quaternarium
Weymouth
England
United KingdomAlbany
Ben Lomond
Berkeley
Bolinas
Brookdale
Santa Cruz
CaliforniaHonolulu
HawaiiCoupeville
Washington
United States