A new species, Ophiocordyceps ponerus, is reported from a survey of invertebrate-associated fungi in Xiaochehe Wetland Park, Guiyang City, China. Evidence for the new species is provided by morphological and molecular characters. Synnemata of this species emerged from cadavers of soldier ants of Ponera sp. (Hymenoptera). It differs from similar species mainly in having verticillate phialides on the upper portions of the synnemata with septa, 112–158 × 7.5–10 μm; cylindrical or oval conidiogenous cells, which are inflated at the base, and suddenly tapering to a short, thin and verrucose neck, 13–25 × 2.5–5 μm; solitary, smooth conidia nearly oval or forming curved orange segments, 7.5–10 × 3.8–5 μm. Phylogenetic analysis using combined ITS, SSU, RPB2 and TEF sequence data support its systematic position in Ophiocordyceps and as a new species.