Biatora oxneri has a whitish to whitish-grey crustose
thallus that is across, although neighbouring thalli may coalesce to form larger spots. A thin (>0.2 mm wide)
hypothallus is observed where the thallus border another crustose lichen. The
apothecia, which are in a transitional state between
biatorine- and
byssoid-type, are closely attached to the thallus and measure 0.2–0.9 mm in diameter. The apothecial disc ranges in colour from dark violet to blackish violet to ink blue; it is initially concave or flat, later becoming convex. The
asci are of the "Lecanorine"-type and contain eight spores. These
ascospores have a shape described as narrowly
bacilliform to somewhat lens-like, and measure 8–13 by 2–3.2
μm. All of the standard
chemical spot tests on the thallus are negative, while the N-test (35% solution of
nitric acid) produces a violet-purple colour on the
hymenium and subhymenium.
Biatora pacifica, described as new to science in 2016 from
Sakhalin, is similar in appearance to
B. oxneri, and the authors suggest that it may be an esorediate version (i.e., lacking
soredia) of this species. ==Habitat and distribution==