As part of a revision of the Leptogium saturninum group in North America, we described L. cookii D. F. Stone & Lendemer as a new species from the western United States and Canada (Stone et al. 2016). The separation of L. cookii from other members of the group was based on a combination of morphological differences (isidium morphology, medulla anatomy and thallus colour) with support from molecular phylogenetic analyses. Unfortunately, in the protologue we selected as type a specimen that had not been sequenced and which subsequent study by Matthias Schultz and Bruce McCune has demonstrated is conspecific with L. saturninum (Dicks.) Nyl. s. str.