Siphonocladus rigidus
- kingdom: Plantae
- phylum: Chlorophyta
- class: Ulvophyceae
- order: Siphonocladales
- family: Siphonocladaceae
- genus: Siphonocladus
- species: Siphonocladus rigidus
Duncan Town
Ragged Island
BahamasCutler
East Perrine
Key West
Palmetto Bay
Florida
United States