Caloplaca tephromelae Kantvilas, Suija & Motiej., a lichenicolous species growing on saxicolous thalli of species of Tephromela, is described from Tasmania. The new species is characterized by lecanorine to zeorine apothecia with a whitish grey thalline margin devoid of anthraquinone pigments, a non-inspersed hymenium, paraphyses without oil vacuoles and ascospores 10–14 × 5–8 μm, with a septum 5–8 μm thick. It is compared with selected taxa of Caloplaca s. lat. that share these salient features. Molecular data support the distinctiveness of the new species but do not suggest any obvious close relatives.

Five taxa of the genera Omphalodina and Rhizoplaca known from continental Antarctica are reassessed in order to identify a remarkable species collected from northern Victoria Land, for which the new combination Rhizoplaca macleanii (C.W. Dodge) Castello is proposed here. This poorly known species is known only from continental Antarctica. Two synonyms are discussed: Omphalodina exsulans (Th. Fr.) C. W. Dodge and O. siplei (C. W. Dodge & G. E. Baker) C. W. Dodge are synonyms of Rhizoplaca melanophthalma (DC.) Leuckert & Poelt. The correct name of another species is Tephromela priestleyi (C. W. Dodge) Øvstedal. The name O. johnstonii (C. W. Dodge) C. W. Dodge should be abandoned, type material being too scanty for a reliable identification. A contribution to the flora of the Terra Nova Bay area (northern Victoria Land) is provided, with two additional species, including Buellia vilis Th. Fr. new to Antarctic regions, and two nomenclatural corrections.