Names and genus type
POWO accepts the name Oehmea beneckei (C.Ehrenb.) Buxb. The combination was published in Sukkulentenkunde in 1951. Older literature contains the names Mammillaria beneckei and Dolichothele beneckei. POWO places taxa including Mammillaria balsasoides, M. guiengolensis and the taxon called Oehmea nelsonii within the same species. [2-WWW]
Buxbaum based the genus Oehmea on O. nelsonii, also associating Mammillaria beneckei with a similar group. The later unification of these names means that studies of the distinctness of Oehmea must include the lineage represented by current O. beneckei. The 2026 nomenclatural paper cited this history as the basis for correctly applying the genus name. [Breslin and Majure 2026, e331, section on Oehmea]
Stem, tubercles and hooked spine
The original description of Neomammillaria nelsonii material, now included in Oehmea beneckei, presents a globose stem 5 cm in diameter. The numerous cylindrical tubercles are 5–7 mm long, with glabrous axils. About fifteen white, needle-like radial spines reach 6–8 mm. Among the several central spines, one is distinctly thicker, brown to black, strongly hooked and 12–15 mm long. The others resemble radial spines. These measurements concern E. W. Nelson's material from the La Salada cliffs in Michoacán, collected on 23 March 1903, number 6932. [Britton and Rose 1923, p. 163, material described as Neomammillaria nelsonii]
Flowers, fruits and seeds
The diagnosis in The New Cactus Lexicon describes flowers about 2–2.5 cm long and 3–4 cm in diameter. The inner tepals are orange-yellow, the outer tepals green, and the stigma has three to five orange lobes. [Hunt et al. 2006, p. 150; Mammillaria beneckei]
In Britton and Rose's description, fruits of the nelsonii material are red, very slender, club-shaped, 3 cm long or more, with few seeds. The globose black seeds are about 2 mm in diameter and have an unevenly sculptured coat. At the base is a recessed, triangular white scar marking the seed's connection to the funicle (hilum). Large seeds subsequently played an important role in the historical separation of Oehmea. [Britton and Rose 1923, Britton and Rose, p. 163, scope of the nelsonii material] [Breslin and Majure 2026, Britton and Rose, p. 163, scope of the nelsonii material]
Range and environment
The native range given by POWO includes western and central Mexico. The species is a succulent subshrub assigned to the desert and dry scrub biome. Breslin and Majure discuss O. beneckei as part of a broader, primarily Mexican tropical Oehmea group, with some records extending to Sinaloa. The database biome entry and the regional picture of the genus have different spatial scales. [2-WWW] [Breslin and Majure 2026]
Characters in the discussion of relationships
The separation of the historical Oehmea group was linked to large flowers and large seeds with an uneven, tuberculate surface. Breslin and Majure return to these characters when justifying genus boundaries. This characterisation describes the basis of the classification. Comparing organ size with other species requires measurements from their own diagnoses. [Breslin and Majure 2026, e331]
In the 2023 study by Chincoya and colleagues, Oehmea beneckei material (called Mammillaria beneckei in the paper) was placed in a lineage containing species traditionally assigned to broadly circumscribed Mammillaria. This part of the tree also contained M. napina and M. zephyranthoides. The authors identified a need for further investigation of genus boundaries. In 2026, Breslin and Majure presented an expansion of Oehmea, citing further phylogenomic findings. [Chincoya et al. 2023, Chincoya et al., pp. 5–8, 12–14] [Breslin and Majure 2026, Chincoya et al., pp. 5–8, 12–14]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Anonim b.d.z, file p. 1]
Synonyms and names in the literature
Mammillaria beneckei · Dolichothele beneckei · Mammillaria nelsonii · Neomammillaria nelsonii · Oehmea nelsonii · Mammillaria balsasoides · Mammillaria guiengolensis [2-WWW]