Hamatocactus bicolor is the
correct name within Hamatocactus but care should be taken NOT
to equate Hamatocactus bicolor with Thelocactus bicolor
which is an entirely different plant.
We are employing H. setispinus as the title
for this entry simply to lessen chances of confusion between the two
Inclusion of setispinus within Thelocactus
seems questionable as this species lacks tubercles (except as young
seedlings) & lacks fruit dehiscing via a basal pore. It also has
divergent seed morphology.