Marshallocereus in Cact. Succ. J. (Los Angeles) 22: 154. 1950 sec. Arias 2021
- Type: Marshallocereus aragonii
Category B. The genus is monophyletic based on phylogenetic studies that support the clade based on a sufficiently dense or even complete sampling, or support a monotypic genus as a distinct lineage, but do not provide a new taxonomic treatment at the species level. In many cases, older classical taxonomic synopses or a monographic treatment exist for these genera providing a reliable assessment of the species included.
Phylogenetics: Some phylogenetic analyses and taxonomic studies confirm that Marshallocereus belongs to the Pachycereinae subtribe, but its relationship with Cephalocereus and Pachycereus is still uncertain (Arias & al. 2003; Arias & Terrazas 2006, 2009). Its distribution is one of the southernmost of Pachycereinae, in the Mesoamerican region (Mexico to Costa Rica). The recognition of more than one species is not resolved.A
A. Arias, S. 2021: Revisions of Acanthocereus, Aporocactus, Astrophytum, Bergerocactus, Cephalocereus, Disocactus, Marshallocereus, Nyctocereus, Pachycereus, Peniocereus, Pereskiopsis, Selenicereus, Stenocereus, Strophocactus. – In: Korotkova N. & al., Cactaceae at Caryophyllales.org – a dynamic online species-level taxonomic backbone for the family. – Willdenowia 51: 251-270