lunalaria, and the diminutive inside it
heard as lunalaria
spelled lunularia
Lunularia. The third vowel is another u.
What the ear did
The -ul- is the Latin diminutive, the piece that turns luna into a little moon. It is the same fragment as in globule, nodule and lunule, and it never changes vowel.
L-U-N-U-L-A-R-I-A
The full entry for lunularia covers the name itself.