Sánchez D., Vázquez-Benítez B., Vázquez-Sánchez M., Aquino D., Arias S., Phylogenetic relationships in Coryphantha and implications on Pelecyphora and Escobaria (Cacteae, Cactoideae, Cactaceae), PhytoKeys, 2022, 188:115-165, doi: 10.3897/phytokeys.188.75739
A study of five plastid DNA regions, sequence length changes and eight morphological features. It analyses Coryphantha boundaries and relationships between Escobaria species and the two classical Pelecyphora species. It proposes expanding Pelecyphora and publishes new combinations with type and synonym documentation. It discusses tubercle grooves, tepal margins and seed coat sculpturing, including exceptions in P. chihuahuensis and P. macromeris.