The Hohner Lucia was produced in several variations:
Lucia II, which had 80 basses, LMM, there is a 'musette' model too, which had a more pronounced musette tuning instead the standard Hohner tuning (16 cents).
Lucia III, these were the same as II but had 96 basses. There is a variation with LMH, which was the Lucia IIIp, so the "p" stands for picollo. These straight tuned models were advertised as tango models.
So the Lucia IV is the musette model LMMM, with the standard Hohner tremelo around 16 cents under and above the concert tuned middle reed. The Lucia IVp is LMMH, with the highest reeds indicated by the letter "p".
The Hohner Lucia IVp was often called the "little Atlantic".
I really like these instruments and I don't agree on Paul DeBra's sentiment that they sound harsh. They were produced in different colours, look them up!
Currently I own three of them, but I still hope to score a green Hohner Lucia IV some day!