Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Life habit: lichenicolous Thallus: lacking, or with hyaline to pale brown vegetative hyphae Ascomata: perithecioid, black, ostiolate, immersed or becoming sessile ascomatal wall: pseudoparenchymatic, black or brown, lower part blackish brown, pale brown, or hyaline, mainly 3-8 cell layers thick, upper part sometimes clypeus-like thickene hamathecium: ostiolar filaments (= periphyses) present, not branched, or absent, interascal elements present or absent, mainly short pendant pseudoparaphyses of type a or type b (see Roux and Triebel 1994, Calatayud and Triebel 2003) or rarely with paraphysoids (in Stigmidium psorae groups, see Calatayud and Triebel 2003), interascal gel not hemi-amyloid asci: clavate to subcylindrical, ascus wall apically thickened, bitunicate, fissitunicate, outer layers of ascus wall not hemiamyloid, 4-8-spored ascospores: hyaline or more rarely pale brown to brown when mature, 1(3)-septate, ovoid, ellipsoid, oblong or fusiform-elongate, 7-23 x 2-7.5 µm; ends: obtuse or aciculate; walls: smooth or weakly warted, with or without a gelatinous sheath Conidomata: pycnidial, immersed; wall: dark brown conidiogenous cells: hyaline, terminal conidia: hyaline, short bacilliform Geography: world-wide, but mainly in temperate regions Substrate: thallus and apothecia of lichens on all substrates. Notes: The generic circumscription of Stigmidium is still insufficiently determined and some taxa will have to be excluded in the future. Especially Stigmidium psorae and some related species have closer affinities to Sphaerellothecium and should be separated when more data, e. g. on the ontogeny of hamathecial elements of the whole group, are available (see Calatayud and Triebel, 2003). Triebel et al. (1991) erroneously recorded Stigmidium congestum for the Sonoran region: the corresponding specimen (Nash III 11758, ASU, on Lecanora carpinea agg.) belongs to Sphaerellothecium propinquellum (Nyl.) Roux & Triebel (see Roux and Triebel, 1994).