The plural form of melisma is melismas or melismata.

What is the plural of melisma?

noun. me·​lis·​ma | \ mi-ˈliz-mə \ plural melismata\ mi-​ˈliz-​mə-​tə \

What does melismatic mean?

(mə-lĭz′mə) pl. me·lis·ma·ta (-mə-tə) or me·lis·mas. A passage of multiple notes sung to one syllable of text, as in Gregorian chant.