Dense white woolly flecks cover the plants body
 

The fruit of A. coahuilense  (left) is pinkish and opens basally, it is very different from the fruit of 
A. myriostigma (right) which is very hairy,  dehisces apically and has a greenish inner colour.

Astrophytum coahuilense with five ribs, has a surprising similarity to A. myriostigma. However, it is different in all characteristics regarding flower, fruit, seed and embryo which looks like in all details to Astrophytum capricorne. The differences into flower, fruit, seed and embryo and flecks are constant and permit in any case to distinguish Astrophytum coahuilense without problems from A. myriostigma.
Nude plants as in the case of Astrophytum myriostigma are unknown.
It looks like the bishop's cap (A. myriostigma), but softer, more grey flecks that cover the plant even more than with the myriostigma.  The flowers are yellow with a characteristic red throat, although can appear pure red or very seldom pure yellow. In the fruit which is red till olive-green coloured and basal opening are up to 200 seeds, similar as in the case of Astrophytum capricorne. This plant is more related to the  Asterias/capricorne group than the myriostigma.
A. coahuilense and A. myriostigma when cross-pollinated are fruitless: they are (usually) sterile by each other.

Flowers are yellow with a characteristic red heart.

Photo of conspecific taxa, varieties, forms and cultivars of A. cohauilense:

• Astrophytum coahuilense
• Astrophytum coahuilense kikko

Conservation status: Listed in CITES appendix 2.

Origin:  South-western Coahuila and Durante (Ciudad Lerdo, Sierra Baicuco, western Sierra Parras and southern of this line up to the Sierra of El Numero)

Habitat: They inhabit preferentially sunny south and east slopes on lime formations, rarely grow in north or west position between white grey rock in a loose to thick vegetation, which mainly consists of a dry bush community. The soil, consist mainly of lime gravel and sand with isolated humus feedthroughs.

In habitat near Lerdo,  Durango  in association with Hetchia sp. and Thelocactus bicolor
( Photo and © Copyright by Marco Antonio Arroyo - Mexico )

( Photo and © Copyright by Marco Antonio Arroyo - Mexico )
 

A young cultivated specimen 
(SB1474 Lerdo, Durango, Mexico)