The Thelotremataceae is a predominantly tropical group, with only eight species known from Europe (Purvis et al. Reference Purvis, Jørgensen and James1995; Mangold et al. Reference Mangold, Elix and Lumbsch2006). Two of these eight species are only known from the Azores. One, Thelotrema antonini Purvis & P. James, is common in the upland regions of the Azores and is also known from Tanzania (Frisch 2006). It is not a Thelotrema in the strict sense, but belongs to an aggregate of uncertain affinities. Due to the heavy carbonization around the pore it resembles a pyrenocarpous lichen and is often wrongly identified as a Pseudopyrenula. It could be expected that a new genus will be erected to accommodate this group, but the species will not be reclassified here.

The other European species known only from the Azores is the taxon that was described as Thelotrema perforatum var. pauciseptatum Purvis & P. James. Although described in the genus Thelotrema, it (like the preceding species) differs from that genus in its present sense (and in the sense in use when it was described in 1995) in many characters, most notably the presence of a columella and the absence of periphyses. This species belongs to Ocellularia, differing from the preceding species in having, for example, ascospores that react IKI+ violet. This Ocellularia differs from all other species accommodated in the genus. It keys out close to O. vezdana Frisch (2006), but differs by consistently having fewer septa in the ascospores (3–5 versus 3–8) and, in particular, by the ascocarp rim, which is prominent and exserted, but is immersed in O. vezdana.

Although this taxon is similiar to the pantropical Ocellularia perforata (Leight.) Müll. Arg., there is no a priori reason to assume that these two taxa belong to the same species. The differences are marked, with the ascospore septation (3–5 versus 5–9) being the most conspicuous. Ascospore septation may be variable in Thelotremataceae species, but this is more marked when there are significantly more septa (e.g. >12), and less so when there are fewer septa; the difference between 3–5 and 5–9 septa is significant in all known Thelotremataceae. Further differences include a dense inspersion of the hymenium with tiny KOH-soluble crystals, ascospores that slowly turn brown and to some extent the variation in pore width, which is generally quite large, of the order of 2–3 times within a single specimen in the Azorean material (generally much smaller in O. perforata) and thallus colour (essentially grey in the Azorean material but greenish in O. perforata). As a consequence this taxon is now raised to species level.