Most species in Ceratocystiopsis share many characters with species in Ophiostoma. Unlike other Ceratocystiopsis species, C. falcata appears to have enteroblastic conidium development and what appears to be a Chalara anamorph. Morphologically, Cp. falcata is thus more similar to Ceratocystis (with Chalara anamorphs) than Ophiostoma, although it is very distinct from Ceratocystis in perithecial characteristics. Recent studies using molecular data have shown that, despite its peripheral similarity to Ceratocystis, Cp. falcata is distantly related to either Ceratocystis or Ophiostoma. In view of this molecular evidence a new genus, Cornuvesica, is described for it, characterized by having falcate, sheathed and septate ascospores. The anamorph of Cornuvesica is morphologically similar to Chalara but conidia are obovoid with only one truncate end. Conidia are apparently not produced by ring wall building and Chalara is not an appropriate genus for it. We suggest that the anamorph of Cornuvesica represents a genus distinct from Chalara.