Origin and Habitat: Coahuila, Mexico.
Altitude: 1000 to 1230 metres above sea level.

• Mammillaria coahuilensis subs. albiarmata (Boed.) D.R.Hunt
• Mammillaria albiarmata Boed.
• Mammillaria coahuilensis var. albiarmata (Boed.) B.Hofmann

• Mammillaria coahuilensis (Boed.) R.Moran
• Mammillaria heyderi subs. coahuilensis (Boed.) Lüthy
• Porfiria coahuilensis Boed.
• Mammillaria coahuilensis var. albiflora (Boed.) Boom
• Porfiria coahuilensis var. albiflora Boed.
• Mammillaria schwartzii (Frič) Backeb.
• Haagea schwarzii Frič
• Neomammillaria schwarzii Rose & Frič
• Porfiria schwarzii (Frič) K.Crkal

• Mammillaria coahuilensis subs. albiarmata (Boed.) D.R.Hunt
• Mammillaria albiarmata Boed.
• Mammillaria coahuilensis var. albiarmata (Boed.) B.Hofmann

Description: Mammillaria coahuilensisSN|15100]]SN|15100]] subs. albiarmata best known as Mammillaria albiarmataSN|20939]]SN|20939]] is one of the local form of Mammillaria coahuilensisSN|15100]]SN|15100]]. It distinguishes from the type species for its more numerous spines.
Habit: It is a small solitary, geophyte cactus, with a heavy tap root that may exceed the size of the plant above soil level.
Stems: Flattened globose, strongly tuberculate basally, blue-green, up to 5 cm high and in diameter.
Tubercles: 3-angled in cross section. Axils moderately woolly. Without latex.
Spines: About 20-25, up to 6 mm long. thin, bristle-like radial spines, slightly pubescent white or creamy white with darker orange-pink tips, becoming yellowish brown.
Central spine: Not present.
Flowers: Broadly funnelform, up to 20 mm broad, creamy-white with pinkish midveins
Blooming season: Late winter to early spring (February/March)
Fruits: Red clavate.
Seed: Dark brown, distinctly pitted.

Notes: Mr. Reppenhagen regards Mammillaria albiarmataSN|15100]]SN|20939]] as a synonym of Mammillaria coahuilensisSN|20939]]SN|15100]] whereas Dr. Hunt asserts that it is a form of it with more numerous radial spines.

Bibliography: Major references and further lectures
1) Nathaniel Lord Britton, Joseph Nelson Rose “Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family” Courier Dover Publications, 1963
2) 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
3) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006 ISBN 0953813444, 9780953813445.
4) Edward F. Anderson “The Cactus Family” Timber Press, 2001
5) John Pilbeam "Mammillaria" Cirio Pub. Services, 01/Dec/1999

Cultivation and Propagation: This species has few special demand and whatever view one adopts it is worth a place in every Mammillaria collection.
Be careful with watering, which all thick rooted species require (rot sensitive), and patience to match its slow growth. During the winter rest, the plant may pull near the surface of the potting mix.