Astrophytum coahuilense with five ribs, has a surprising similarity to Astrophytum 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 A. coahuilense without problems from A. myriostigma.
Nude plants as in the case of A. 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.