Diagnosis. A saxicolous species with thalli composed of dull, yellow-orange to deep orange, typically widely dispersed areoles, their surface consistently epruinose (even when growing on calcareous substrates), areoles usually developing on a faint, thin, ± shiny, whitish to blackened hypothallus, in some specimens distinctly separating several thalli as a distinctly blackened prothallus, apothecia adnate, disc epruinose, concolorous or barely deeper in color than the surrounding areoles; ascospores (8.0–)8.5–9.9(–10.4) × (4.0–)4.6–6.8(–7.7) μm, with a moderately thickened, (2.0–)2.6–3.6(–3.8) μm wide septum (n = 15). The new species is reliably distinguished from the morphologically similar species in Squamulea by its different ITS sequence.

Type. Ecuador, Galápagos: Florean, lower S-slope of Cerro Ventanas, 1°16′36″S, 90°25′41″W, 295 m alt., transition zone, open shrubland of Macraea laricifolia and some lower Waltheria ovata shrubs in between, on rock, 18-Jan-2011, Yánez-Ayabaca, A. 2023 (CDS 48373‒holotype; GenBank Accession number nrITS: MT967445).

Chemistry. Thallus and apothecia P–, K+ purple, C–, KC± purplish, UV– (dull); thallus and apothecia with a large proportion of parietin and smaller proportions of teloschistin, fallacinal, parietinic acid and emodin (chemosyndrome A sensu Søchting 1997).

Ecology and distribution. Few specimens currently known, all from the Galapagos, from the dry, through the transition into the humid zone, all from basalt (non-calcareous substrates).

Etymology. The epithet oceanica is derived from the Pacific Ocean, where the type locality on Galapagos is located.

Notes. Squamulea oceanica is, like most Squamulea species in the Galapagos, morphologically ill-defined. Specimens here identified as this species are all epruinose, but unlike pruinose specimens of Squamulea they were not collected on calcareous substrates. Often present between the scattered areoles is a thin, ± shiny, whitish to blackened hypothallus. It can be particularly well-developed as a black borderline delimiting different incompatible thalli. Such a prothallus has also been observed in some of the other species in the group, particularly S. humboldtiana.