[1] The genus was circumscribed by German lichenologist Andreas Frisch in 2006, with Acanthotrema brasilianum assigned as the type species.

The apothecia are erumpent, taking on angular-rounded to lobate (chroodiscoid) forms, with a visible disc and a margin that is lobulate and merged.

[3] Characteristics that differentiate Acanthotrema apart from other genera that possess similar fruiting structures are its chroodiscoid apothecia, spinulose periphysoids, and paraphyses.

However, Chroodiscus does not have periphysoids, possesses paraphyses with smooth apices, and is strictly foliicolous (leaf dwelling).

While certain Chapsa species, such as C. astroidea, may bear a resemblance to Acanthotrema due to the similarity in apothecia and the near-thin-walled, non-amyloid ascospores, these taxa consistently have paraphyses with smooth apices.