This thick-leaved mesemb with its pink (winter) flowers is grown internationally, usually from seed. It grows naturally in the Little Karoo.
Are there more antegibbaeums than fissoides? Eggli and Hartmann in the Illustrated Handbook of Succulent Plants say that Antegibbaeum preceded Gibbaeum in evolution. Maybe the older genus has been reduced in variety over time? They also refer to the fungus that turns old leaves black, as seen in the photo.