Marsicus
Could not find Marsico in Logeion dictionaries.
Marsico proper-name adjective neuter dative singular, proper-name adjective masculine ablative singular, proper-name adjective masculine dative singular, proper-name adjective neuter ablative singular of Marsicus
Mārsĭcus, (14) a, um, des Marses : Cic. Div. 1, 99 ; Agr. 2, 90 ; Mart. 13, 121, 1.