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

Apothecia: 0.15-0.36(-0.45) mm high, often +immersed in the host thallus stalk: absent to short, 0-1.2 times as long as head, black or dark brown capitulum: 0.14-0.25(0.36) mm wide, +spherical but often somewhat expanded vertically and slightly irregular, shiny black or dark brown; SPHINCTRINA exciple: dark brown in section, K-, weakly or not sclerotized asci: cylindrical, when mature 56-78 x 6.8-9.2 µm ascospores: ellipsoidal with pointed ends, non-septate, when mature (9-)12-15.5(-20) x 6-8(-9) µm; surface: with distinctive ornamentation of coarse, longitudinally arranged and reticulately interconnected ridges; spore coat: thin, usually indistinct in water. Substrate and ecology: parasitic or parasymbiotic on thin lichen thalli, e.g., Pertusaria leioplaca and very rarely also on stone World distribution: temperate zones in Europe, Japan, Africa, North and Central America Sonoran distribution: Southern California and Baja California. Notes: An alternative spelling of the name is S. tubiformis. See Tibell (1996a) for fuller description.