Name and distribution
Epithelantha cryptica is an accepted species in POWO, occurring naturally in Coahuila in northeastern Mexico. Donati and Zanovello published the name in 2011. [2-WWW]
Sites and climate
In the environmental analysis, E. cryptica sites occupied one of the soil categories distinguished, whereas E. micromeris occupied four. However, no statistically clear association with a specific soil category was found for E. cryptica. The climate of its sites was on average warmer and wetter than the environment of E. micromeris. [Aquino et al. 2021, p. 4524–4527, ryc. 3–4]
Species recognition and DNA markers
The four plastid DNA regions used in the 2021 study showed such great similarity between E. cryptica and E. micromeris that they did not independently provide a clear distinction between the species. The authors considered their different morphology and environment. This set of data supported retaining E. cryptica as distinct, while indicating a need for a more detailed study of relationships among populations. [Aquino et al. 2021, pp. 4525–4527]
Flower and areole as diagnostic traits
In the 2019 revision, Epithelantha cryptica was studied in 15 adult plants from three sites. Flowers were 11–12 mm long, measured from the base of the pericarpel to the tip of the longest tepal. The oval areoles in the key were 0.60–0.75 mm wide. They were accompanied by ordinary slender roots and no distinct underground stem section. This combination helps distinguish the species from E. micromeris, whose flowers and areoles were smaller. [Aquino et al. 2019, p. 605, 608, 612, 615; tabela 5]
Samples of E. cryptica and E. micromeris had very similar sequences in four plastid DNA regions. Morphological differences separated adult plants of the two groups. In an analysis combining DNA with ten coded structural traits, E. cryptica received support as a distinct lineage. The authors based species recognition on a consistent picture from several traits, given the limited resolution of the plastid markers alone. [Aquino et al. 2019, p. 605–609; ryc. 3–4]