Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: continuous, rimose, usually with numerous, unpigmented cracks but few cracks in young or poorly developed areas, thin to moderately thick (up to 0.25 mm in fertile parts), thinning at margins, surrounded by a dark prothalline line, areoles: flat (sterile ones) to slightly convex (fertile), 0.2-0.5 mm wide (fertile ones up to 0.7 mm) surface: gray-green, greenish ochre to brownish green, smooth, dull to somewhat shiny anatomy: upper cortex: ill-defined, composed of 1-3 rows of cells 3-6 µm in diam., not overlain by an epinecral layer; algal layer: paraplectenchymatous, with equal sized cells 5-10 µm in diam., irregularly thick (70-100 µm); alga-free medulla: thin, subparaplectenchymatous or partly with filamentous hyphae, colorless to slightly brown, enclosing substrate particles, without a dark basal layer Perithecia: fully sunken in thallus with only the apices projecting to slightly bulging the surface or immersed in hemispherical thalline warts, covered with thallus to near apex, or tips naked, the apices black, slightly convex to flattened, round or somewhat irregular in outline; exciple: subglobose, pale to brown, 0.2-0.3 mm wide, 15-20 µm thick; involucrellum: well-developed, conical-hemispherical, dark brown (with a reddish tinge in thin sections), reaching down to exciple base level, basally more or less spreading from the exciple, 60-200 µm thick at base, the lower inner parts slightly paler and of "Zellnetztyp", often containing large oil droplets; periphyses 30-40 µm long, simple to scarcely branched, with gelatinizing walls and thus united in a common gel asci: clavate, 65-75 x 20-25 µm, 8-spored ascospores: hyaline, simple, ellipsoid, (15-)16-23(-25) x 7-10 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on both limestone and weakly calcareous siliceous rocks usually in shaded habitats, on damp to rather dry rocks, montane; the Sonoran samples from siliceous rocks in canyons and woodlands World distribution: northwestern and central Europe, southwestern North America Sonoran distribution: Arizona (Cochise and Santa Cruz Counties) and California (Santa Monica Mts.). Notes: Verrucaria elaeina resembles the freshwater species Verrucaria praetermissa from which it differs in the lack of a black basal layer and in better developed involucrella. The spores are slightly smaller (but ranges overlap considerably) and lack a perispore. Furthermore, it differs ecologically in that it occurs in drier situations. Though found on places away from water, it has a "Zellnetztype" involucrellum as is typical for freshwater species.