Ocellularia brasiliensis is a corticolous (bark-dwelling), crustose lichen in the family Graphidaceae. The species was described in 2014 from primary rainforest near Porto Velho in Rondônia, Brazil, where it grows on tree bark in shaded understory conditions. It forms uneven gray patches with whitish to light yellow-green powdery structures and has rounded fruiting bodies with a black central column. It differs from O. africana in having a blackened () apothecial wall and central column (), and in producing a distinctive yellow lichen substance ("cinchonarum unknown").
The species was described in 2014 by Marcela Cáceres, André Aptroot, and Robert Lücking as part of a survey of Graphidaceae diversity in Rondônia, Brazil. The holotype was collected on March 8, 2012 at the Federal University of Rondônia campus south of Porto Velho on tree bark in primary rainforest; it is housed at ISE (Herbário da Universidade Federal de Sergipe).
In their the authors contrasted O. brasiliensis with O. africana: the new species has a carbonized and and a "cinchonarum unknown" chemistry, whereas O. africana has uncarbonized apothecial structures and a different chemical profile.
The thallus is corticolous and epiperidermal, forming uneven, grey patches that are sorediate; the soredia (soralia) are dispersed to clustered and measure about 0.3âÂÂ0.6 mm across, whitish to light yellow-green, with no evident . In section the thallus is 50âÂÂ80 üm thick with a cortex 10âÂÂ15 üm thick, a 30âÂÂ50 üm thick of Trentepohlia whose cells are roughly 7âÂÂ11 à6âÂÂ9 üm, and a thin, irregular medulla containing scattered calcium oxalate clusters.
The apothecia are rounded, to prominent, with an almost complete 0.5âÂÂ0.8 mm in diameter and 0.2âÂÂ0.25 mm high. The is covered by a 0.2âÂÂ0.4 mm pore largely filled by a black, broad-stump-shaped (about 300âÂÂ400 üm wide, 100âÂÂ120 üm high). The is entire and carbonized (30âÂÂ60 üm wide); the forms a narrow, clear ring 90âÂÂ100 üm high around the columella; the is hyaline and . Paraphyses are unbranched and smooth; are absent.
Ascospores (eight per ascus) are ellipsoid, 7âÂÂ9-septate, 20âÂÂ28 à6âÂÂ7 üm, hyaline, and with lens-shaped ; they stain iodine-positive (I+) violet-blue (amyloid). The chemistry includes a "cinchonarum unknown" lichen substance; the medulla is P+ (red) and the microscopic section is KâÂÂ.
Ocellularia brasiliensis was originally known from primary rainforest in Rondônia, Brazil, where it grows on smooth tree bark in shaded understory conditions near Porto Velho at around 100 m elevation. It has since been recorded in Mato Grosso.