Wiktionary
phytane
n. (context organic compound English) A diterpenoid alkane with one more carbon than pristane.
Wikipedia
Phytane
Phytane is a type of diterpenoid alkane. In contrast to pristane, which is formed from the dehydroxylation of phytol, it has one extra carbon.
Phytanyl is the corresponding substituent. Phytanyl groups are frequently found in phospholipids in membranes of thermophilic Archaea. These include caldarchaeol, a compound which contains two fused phytanyl chains.
It is used as a bio-marker in petroleum studies.