Novel methoxylated FA from the Caribbean sponge Spheciospongia cuspidifera

The Δ 6 monoenoic methoxylated FA (6 Z )‐2‐methoxy‐6‐heptadecenoic acid and (6 Z )‐2‐methoxy‐6‐octadecenoic acid were identified for the first time in nature in the phospholipids from the uncommon Caribbean sponge Spheciospongia cuspidifera . These findings expand the occurrence of Δ 6 2‐methoxylated FA to C 17 −C 18 chain lengths and establish a new FA biosynthetic possibility for these marine organisms. The novel methoxylated FA also could have originated from the phospholipids of a bacterium in symbiosis with the sponge.