A rare Gymnocalycium species that's almost never seen in Japan. It grows at elevations of 900–1100 meters in the Sierra de Ambato in Catamarca, Argentina. It has a chunky, rugged body about 7–15 cm wide, ranging in color from green to olive green, and is covered in long, thick spines that are yellow to brown and turn gray as the plant ages. If you image-search it, you'll often find sample shots where the spines are pretty slender (like in the DETAIL image), but the MAIN image is a different story. To be frank, it looks exactly like G. castellanosii ssp.ferocius . There's also the fact that it's been distributed via China under the name "狂刺碧岩玉" (which is actually its origin), which supports the theory that it's often confused with ferocius.
However, if you look up the original description and field reports for ambatoense, the main traits are actually quite close to those of ferocius, and ambatoense has even been treated in the past as part of the hybopleurum group ), with Llifle still considering them the same species now. So the name "狂刺碧岩玉" kind of makes sense, too. In short, just looking the same isn't quite enough to say it's been confused with ferocius—I think we'll need to compare things like their flowers and mature forms to really be sure (though even their flowers are almost the same: apparently, ambatoense's are white with pink vertical stripes, while ferocius has white or pale pink flowers with a deeper pink base).

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  3,800JPY