Distribution of long chain heterocyst glycolipids in cultures of the thermophilic cyanobacterium Mastigocladus laminosus and a hot spring microbial mat

► Long chain (C30 and C32) heterocyst glycolipids (HGs) occur in an Icelandic hot spring microbial mat. ► First report of these long chain HGs in the environment. ► Mastigocladus laminosus is the source of the long chain HGs. ► Proportion of individual HGs shows a temperature dependence in cultures of M. laminosus. ► Long chain HGs represent biological markers for cyanobacteria of the order Stigonematales.