Astrophytum coahuilense?

[BarryRice]

Hey folks!

I know that Astrophytum coahuilense is often reduced to synonymy with A. myriostigma, but is there much of an active dissenting view?

They seem so different to my eye....

[iann]

A typical non-profession-botanist cactus collector will place a plant with five spines in a different species to one with three spines, and challenge you to a cage fight to the death to defend that opinion. What do you think they make of Astrophytum coahuilense

Although frequently referred to synonymy with A. myriostigma, or as a variety or subspecies of it, it is more likely to be related to A. capricorne. I can't find any publication ever formally making a referral to A. capricorne. Imagine the horror of the amateur splitter if that was forced down their throats The NCL recognises A. coahuilense as a separate species. This is regarded almost as a given in non-British European circles, perhaps because it was named by a German US and Mexican treatment has tended more to leave it lumped. There is no means to formally unlump, so the NCL recognition is about as formal a declaration of separate status as you're likely to find.

[CoronaCactus]

A. coahuilense differs from A. myriostigma in fruit, flower and seeds along with having heavier flecking covering the body completely and it has a velvet-like touch. The flower is yellow with a red throat or rarely a pure yellow flower.

[BarryRice]

Hey Folks,

Thanks for the detailed information, Ian. I am a botanist, but my professional interests are not in cacti, and as such I'm not versed with how the current lumping/splitting winds are blowing with them. As you noted, I am oh-so-familiar with how some collectors, who fall deeply in love with their plants, are prone to feel that minute differences (such as 3 vs. 5 spines!) merit taxonomic recognition.

However, with Astrophytum coahuilense, there are a number of correlated differences that Darryl noted, that really impress me. In particular, the body flecking and method of fruit dehiscence (I understand A. coahuilense fruit do not split apically?).

Cheers

Barry

[daiv]

There are also fertility issues - I am pretty sure that A. coahuilense does not cross with A. myriostigma. Of course, facts like that on their own don't help, but must be interpreted. After all. A. myriostigma does cross with A. asterias, but that doesn't make them the same species.

[BarryRice]

Does A. coahuilense cross successfully with A. capricorne? I think Ian's claim that A. capricorne and A. coahuilense may be more evolutionarily closely related than to A. myriostigma a fascinating conjecture. Is this supported by native ranges?

[tudedude]

My coahuilense seedlings grow so much slower than myriostigma. Even the graft growth rate seems slower than the myriostigma graft. Not sure if that signifies any separation though.

[masscactus]

Hi All - I bought A. coahuilense from Miles years ago. It was smallish when I got it and has been a very slow grower, I have yet to see a flower but the past two or three years we have seen aborted buds. In contrast a small A. myriostigma (one of the quad types) half its size has flowered two of three seasons I have had it. I remember reading A. coahuilense was slow to grow, slow to flower, and to expect a red throat when it does.