Southern Portugal to Mediterranean, and some places in SW. France (introduced). The atlantic part of the distribution range overlaps with that of the parent species H. tuberculata tuberculata Linné. Herbivore and grazer in the upper infralittoral, in rocky environments. The subspecies is characterized by a smaller size than in the parent species, a more lengthened shape, a larger variety of colours and patterns, its stronger spiral sculpture (grooves or plates, sometimes scales) and finallly by its capacity to develop extremely pronounced growth marks (folds, lamellae).
 
Nota bene that many researchers consider lamellosa as a clinal variant of tuberculata Linné, and don’t accept the taxon and the rank of subspecies.

On rock, Paralia Mourtiás, Mortiá, SE. Magnesia, Thessalia, Greece. – Original picture provided by C. Taklis for iNaturalist – (CC BY). Notice, between the numerous tentacles, the small digiform epipodial projections (pale green). In mykonosenesis, these projections are much bigger, and highly ramified.