Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Mycelium: hyaline, immersed in the host thallus, inconspicuous Ascomata: solitary, entirely immersed in the host thallus, normally only the ostioles visible as small dots, obpyriform, 60-130 µm in diam.; ascomatal wall: colorless, but sometimes the ostiolar region lightly brown, 3-5 layers thick; centrum: K/I- hamathecium: indistinct or absent asci: clavate, 4-8-spored, 40-55 x 7-9 µm ascospores: hyaline, fusiform to limoniform, rarely almost ellipsoid, smooth, 10.5-15 x 4-7.5 µm, ratio length/width: 2.3 Conidiomata: unknown. Hosts: Leptogium saturninum; hosts known outside the Sonoran region: Leptogium gelatinosum, L. lichenoides, L. teretiusculum and L. sp; immersed in the thallus, commensalistic World distribution: Europe (Austria, Great Britain, Greece, Sweden), Macaronesia (Madeira) and North America (USA) Sonoran distribution: so far known only from a single locality in central California (San Benito Co., Pinnacles National Monument) outside of the Sonoran region, but it is expected in the Sonoran region, as its host is common there. Notes: Following Hoffmann and Hafellner (2000), Obryzum corniculatum has fusiform to almost limoniform ascospores, whilst the second species of the genus, O. friesii (Keissler) Nik. Hoffm. & Hafellner has oval to ovoid ascospores. Furthermore, O. friesii is distinguished by its slightly longer and narrower ascospores (13-16 x 3-6 µm; ratio length width: 3), by a more distinct, elongate ostiolar channel, and by more distinct periphyses. The ascospores in the Californian specimen are fusiform to elongate ellipsoid, somewhat intermediate between those of both species. However, their dimensions and length/width ratio, and also the ostiolar region fully agree with O. corniculatum. As O. friesii is known only from the type specimen, its variability is poorly known, and the observation of a specimen of O. corniculatum with intermediate ascospores let us therefore wonder if O. friesii, a species also known from Leptogium, might just be an extreme form of O. corniculatum. The differences with Myxophora leptogiophila are given in the generic notes above.