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 vegetative hyphae brown to dark brown, forming a superficial net on the host thallus surface or ascomata, or penetrating the host tissue Ascomata: perithecioid pseudothecia, black to brownish black, ostiolate, immersed, semi-immersed to sessile ascomatal wall: entirely brown to brownish black, pseudoparenchymatic, mainly 2-3 cell layers thick, upper part sometimes clypeus-like thickened hamathecium: ostiolar filaments (= periphyses) present, not branched, sometimes very rudimentary, with or without long interascal elements (paraphysoids); interascal gel: not hemi-amyloid, not euamyloid asci: bitunicate (fissitunicate), oval, ellipsoid, clavate to subcylindrical, 8-spored; wall: apically thickened, outer ascus wall layers not hemi-amyloid, not euamyloid, endoascus BCr+ or not ascospores: hyaline or pale brown to dark brown when mature, 1-3-septate, ellipsoid, oblong to subclavate, 6.5-22 x 3-8 µm, obtuse or aciculate, smooth or weakly warted; gelatinous sheath: present or lacking Conidiomata: pycnidial, immersed; wall: dark brown conidiogenous cells: hyaline, terminal conidia: hyaline, short bacilliform Geography: worldwide, mainly in temperate regions Substrate: thallus and apothecia on lichens occurring on bark or rocks. Notes: Some species of Sphaerellothecium have similarities with Stigmidium species and are sometimes misplaced there. Most species of Sphaerellothecium are well characterized by their distinct reticulum of dark brown vegetative thick-walled hyphae. The genus Echinothecium Zopf is closely related but distinguished by its hyphoid appendices originating on the outer pseudothecial wall. Echinothecium reticulatum Zopf was reported once from the Sonoran area on Flavoparmelia caperata (Triebel et al. 1991). As E. reticulatum is often considered as being confined to Parmelia s. str., the identity of the populations on Flavoparmelia require further studies, and the species is subsequently not treated in the Sonoran Flora.