“…Two forms, of which one is coccoid and Gloeocapsa - and Chroococcidiopsis -like, the other filamentous, allegedly heterocystous, and suggested to belong to the Nostocales, occur as photobionts of the putative cyanolichen Winfrenatia reticulata (Taylor et al 1997; Karatygin et al 2009). A further eight forms are filamentous, including Archaeothrix oscillatoriformis and A. contexta (Kidston & Lang, 1921; Krings et al 2009; Krings, 2021 a ); Kidstoniella fritschii , Langiella scourfieldii and Rhyniella vermiformis (Croft & George, 1959; recently merged into one taxon, L. scourfieldii , by Strullu-Derrien et al 2023); Croftalania venusta (Krings et al 2007; Krings, 2021 b ); Palaeolyngbya kerpii (Krings, 2019) and the complex, Stigonema -like Rhystigonema obscurum (Krings, 2021 c ). Loron et al (2023) illustrate what may be another Stigonema -like form.…”