Origin and Habitat: Nayarit, Sierra Huichol , Jalisco, Mexico.
Habitat: It is a cliff-dwelling species that grows among rocks on hillsides at an altitude from 1.800 to 2.400 m

• Mammillaria berkiana A.B.Lau

• Mammillaria mercadensis (Britton & Rose) Patoni
• Chilita mercadensis (Britton & Rose) Orcutt
• Ebnerella mercadensis (Patoni) Buxb.
• Escobariopsis mercadensis (Patoni) Doweld
• Neomammillaria mercadensis Britton & Rose
• Mammillaria berkiana A.B.Lau
• Mammillaria flavihamata Backeb.
• Mammillaria nazasensis (Glass & R.A.Foster) Repp.
• Escobariopsis pennispinosa subs. nazasensis (Glass & R.A.Foster) Doweld
• Mammillaria pennispinosa subs. nazasensis (Glass & R.A.Foster) D.R.Hunt
• Mammillaria pennispinosa var. nazasensis Glass & R.A.Foster
• Mammillaria ocamponis Ochot.
• Mammillaria posseltiana Boed.
• Chilita posseltiana (Boed.) Buxb.
• Ebnerella posseltiana (Boed.) Buxb.
• Mammillaria rettigiana Boed.
• Chilita rettigiana (Boed.) Buxb.
• Ebnerella rettigiana (Boed.) Buxb.
• Escobariopsis rettigiana (Boed.) Doweld
• Neomammillaria rettigiana (Boed.) Y.Itô
• Mammillaria sinistrohamata Boed.
• Chilita sinistrohamata (Boed.) Buxb.
• Ebnerella sinistrohamata (Boed.) Buxb.

Description: Plants at first solitary or clustering in the course of time with up to 40 stems.
Stem: Globose, olive-green to dark green, 4 to 6 cm in diameter with latex. The axil is without bristles occasionally with scarce wool.
Radial spine: Numerous 35 to 38, widely spreading, up to 6 mm long, the upper up to 4 mm, white, fine, needle-like.
Central spine: 5 to 8, one more central, 2 to 4 hooked and 10 mm long, the others 4 to 5 mm long and straight, red-brown, whitish at base.
Roots: Taproots.
Flowers: Bell shaped, deep set, dark purple-pink, not widely opening, to 10 mm in diameter. Perianth-segments oblong, obtuse. Stigmas purple.
Fruits: Club-shaped, 15 - 20 mm long, whitish to pink.
Seeds: Black.
Blooming season: Autumn-winter to spring, the flowers remain open for five or six days, exceptionally more.

Bibliography: Major references and further lectures.
1) Robert T. Craig “The Mammillaria handbook: with descriptions, illustrations, and key to the species of the genus Mammillaria of the Cactaceae” E P Publishing, 1945
2) John Pilbeam “Mammillaria The Cactus File Handbook” Cirio Pub. Services, 01/Dec/1999Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006

Cultivation and Propagation: Requires excellent drainage provided by porous cactus soil (With not less than 50% grit content). We suggest repotting every 2-3 years. Prefers bright light and ample airflow. Outside full sun or afternoon shade, inside it needs bright light, and some direct sun. Water should be carefully applied and only when the soil is dry to the touch, as fits this cliff-dwelling species. Allow soil to drain thoroughly before watering again. Do not water in the winter (Rot prone). Protect from frost. But it's hardy to -5°C if kept dry. During the beautiful season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water. This rarely found species is slow growing, but rewards the patient grower with displays of small dark pink flowers. Winter rest is important to stimulate flowering. Use small sized pots.
Propagation: Direct sow after last frost or cuttings.