Peniocereus (A.Berger) Britton & Rose in Contr. U.S. Natl. Herb. 12: 428. 1909 sec. Arias & al. (2005)



The generic circumscription of Peniocereus was revised based on the molecular phylogenetic study of Arias & al. (2005). Their study based on plastid trnL-F and rpl16 found Peniocereus polyphyletic, its species resolved in three lineages. Peniocereus subg. Pseudoacanthocereus was found to be nested in Acanthocereus, yet both were also paraphyletic. For a classification reflecting these relationships, Peniocereus subg. Pseudoacanthocereus would need to be transferred to Acanthocereus. The other major Peniocereus clade found by Arias & al. (2005) corresponds to Peniocereus subg. Peniocereus.
Peniocereus serpentinus (Lag. & Rodr.) N. P. Taylor was resolved as a separate lineage. Since it is the type species of the earlier-proposed genus Nyctocereus, Arias & al. (2005) suggested reinstating it as monotypic.