The Coryphantha sneedii Complex is Indeed Complex and Continuously Intergrades with Coryphantha vivipara

Abstract: The Coryphantha sneedii complex is a confusing assemblage of the following intergrading or ill-defined varieties: orcuttii, organensis, sandbergii, villardii, albicolumnaria, leei, guadalupensis, sneedii, and possibly other undescribed taxa. These varieties comprise a continuum of morphological forms, many with overlapping or proximate distributions, and with some morphological variability possibly arising from phenotypic plasticity to the point that the various variety names are not warranted. There is also debate about geographic range of varieties, e.g. is the type variety actually found in Carlsbad Caverns National Park, Big Bend National Park, and Bishop's Cap. Not only is it impossible to consistently distinguish individual plants of the different varieties of Coryphantha sneedii (Britton & Rose) A. Berger, but it is also sometimes impossible to distinguish them from the sympatric Coryphantha vivipara (Nuttall) Britton & Rose, especially from C. vivipara var. neomexicana (Engelmann) Backeberg. Coryphantha vivipara and C. sneedii are distinguishable from all other species of Coryphantha by their 0.5–1.0 mm diameter lenticular druses and usually (but not always) having green fruits/pericarpels, but these two species with overlapping distributions are not always clearly distinguishable from one another. I therefore propose subsuming the entire Coryphantha sneedii complex as a single variety of C. vivipara.