Work was completed by a combination of site survey in the autumn-winter 2022 and collation of records made by the author in recent years. 151 taxa of lichens and lichenicolous fungi were recorded on all three SSSIs: 115 in Glannau Aberdaron, 53 in Mynydd Penarfynydd and 89 in Porth Ceiriad (see Appendix 1). 51 of these are notable including: • Heterodermia leucomelos; extensive population in Glannau Aberdaron SSSI. • Caloplaca aractina; one of only three British localities outside of the Lizard, at Glannau Aberdaron SSSI. • Teloschistes flavicans; populations in all three SSSIs. • Heterodermia obscurata; known from two localities in Glannau Aberdaron SSSI and at Mynydd Penarfynydd SSSI. • Physcia clementei; on a picrite outcrop at Mynydd Penarfynydd SSSI, the only North Wales locality. • Rinodina roboris var. armeriicola; possibly new to Wales, on soil terraces in Glannau Aberdaron SSSI. • Endocarpon pusillum var. pallidum; new to North Wales and the first British record this century of this variety (awaiting confirmation), on soil terraces in Mynydd Penarfynydd SSSI. • Protoparmelia montagnei; new to North Wales, found in Glannau Aberdaron SSSI and Porth Ceiriad, Porth Neigwl ac Ynysoedd Sant Tudwal SSSI. Only Glannau Aberdaron SSSI meets the qualification threshold of the MRCSI, the others falling short. All SSSIs have other qualifying features based on the presence of Red List species. Viewed together the three SSSIs form a meta-site of significant maritime lichen interest. There are no immediate threats to the lichen interest. The main management issues relate to grazing management of the coastal heath and grassland habitats. Wales, United Kingdom, Europe