Freitas J. G., Alves L. I. F., Zappi D. C., Almeida E. M. D., Peraza-Flores L. N., Amaral D. O. J. D., Araújo D. B. P., Batista F. R. C., Novelties in Cactaceae from Eastern Brazil: Adding two new species and one new nothospecies to Tacinga (Opuntioideae), Phytotaxa, 2021, 490(3):239-252, doi: 10.11646/phytotaxa.490.3.2
Protologues of Tacinga armata, T. gladispina and the hybrid T. ×flammea, with morphological comparisons, habitat descriptions, phenology and cytogenetic data. The paper includes a key to members of the genus recognised at the time. Comparisons cover segment and fruit armature, tepal number and colour, and karyotype structure.