Tethys fimbria

Recently, a novel class of prostaglandin derivatives, PG-1,15-lactones (Fig. 1) of both E [16] and F [17] series, has been reported to occur in the opisthobranch mollusc Tethys fimbria, along with smaller amounts of some of the corresponding PGs. Some lactones were present mainly in the mucous secretion and dorsal appendages known as cerata, while others were more abundant in the mantle. Fatty acid esters of PGF-1,15-lactones (C9 and Cu) were found only in T. fimbria eggmasses and reproductive glands (ovotestis). The structural variety of the lactones and the data on their distribution in the body... 

Fig. 1. Prostaglandin 1,15-lactones and prostaglandins isolated from Tethys fimbria...

Cimino, G. Crispino, A. Di Marzo, V. Spinella, A. Sodano, G. (1991) Prostaglandin 1,15-lactones of the F series from the nudibranch mollusc Tethys fimbria. J. Org. Chem., 56,2907-11. 

Aside from this work, eicosanoid biosynthesis has been recorded in a nudibranch mollusc, Tethys fimbria [62-64]. This nudibranch produces prostaglandin 1,15-lactones, which are transferred from the mantle to egg masses just before egg fertilization and release [64], again suggesting the compounds are major players in the biology of reproduction. 

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