Ophiocordyceps macroacicularis is an entomopathogenic fungus belonging to the order Hypocreales (Ascomycota) in the family Ophiocordycipitaceae, which parasitize moth larvae. It produces superficial, oval perithecia at the apex of its stroma, and also multiseptate ascospores, while producing Hirsutella-type anamorphs on growth culture media. They are particularly distinguished by the shape and size of their stroma.