| Ariocarpus
              retusus  LRM175, in Tamaulipas, the tubercle edges are raised and
              there is no apical areole. | 
| Ariocarpus
              retusus  LRM175, a plant reminiscent of A. trigonus in form. |  | Ariocarpus
              retusus  LRM175, a plant of typical retusus type but lacking the
              apical areole. | 
    
      | Comments An
      extremely interesting population of A. retusus growing in
      Tamaulipas, The majority of the plants are of distinctive appearance with
      a raised rounded edge to the tubercle and lacking an apical areole, other
      specimens have a more A. trigonus like appearance, typical A.
      retusus types are also present. These plants may represent what Josef
      Halda has described as A. retusus subsp. panarottoi, whilst
      an interesting variant, the plants appear to fall within the range of
      A. retusus subsp. retusus |