Hoornsmania Crous, in Crous et al., Fungal Planet, A Global Initiative to Promote the Study of Fungal Biodiversity 11–21: 11:  (2007).
Index Fungorum number: IF 501110; Facesoffungi number: FoF 06632, 1 morphological species (Species Fungorum 2022), no molecular data available.
Hyperparasitic on Neonectria ditissima. Sexual morph: Unknown. Asexual morph: Hyphomycetes. Conidiophores solitary, brown, arising from superficial hyphae, septate. Conidiogenous cells brown, smooth to finely verruculose, elongate-ellipsoid to fusoid, polyblastic, with 1–2 truncate loci, with somewhat thickened and darkened, but not prominently refractive. Conidia brown, smooth to finely verruculose, broadly ellipsoidal to somewhat fusoidal, occurring in branched, acropetal chains; scars somewhat darkened, thickened, but not refractive (adapted from Crous et al. 2007).
Type species: Hoornsmania pyrina Crous
Notes: Hoornsmania resembles Hormoconis in having pale olivaceous, somewhat warty, branched conidiophores, with acropetal conidial chains, and inconspicuous scars and conidial hila. Hoornsmania is unique in having a distinctive ecological habitat by being hyperparasitic on N. diissima but is unable to grow on nutrient media in culture. The placement of Hoornsmania in Mycosphaerellaceae is doubtful.