Ponce, M.M. (2019). Dryopteris bifrons (Thelypteridaceae): a new synonym of Thelypteris lugubris. Candollea 74: 31–32. In Spanish, English and Spanish abstracts. DOI: http://dx.doi.org/10.15553/c2019v741a4
In the framework of the redaction of the family Thelypteridaceae to be published in the Flora of Paraguay, it was found that Dryopteris bifrons Christ based on a paraguayan holotype is taxonomically identical to Thelypteris lugubris (Mett.) R.M. Tryon & A.F. Tryon and therefore included here in its synonymy.