lichens of the lower ozark region of missouri and arkansas

Key H : Crustose lichens with round apothecia (continued)
52. Hymenium purplish red; apothecia black; on siliceous rocks ..... Tephromela atra
52. Hymenium hyaline below the epithecium; substrate various, but if on siliceous rock,
then apothecia not black .......................................... Lecanora
50. Apothecia immersed, or if superficial, then lacking a thalline margin ................53
53. Ascospores large, > 40 �m long, single or double walled; apothecia either immersed in
corticate verrucae with perithecia-like ostioles, or forming sorediate or pruinose verrucae .
............................................................ Pertusaria
53. Ascospores smaller, to 30 �m long, single walled; apothecia disks exposed .......54
54. Apothecia immersed in a well developed thallus; if saxicolous, on siliceous rocks and
not forming pits in the substrate ..........................................55
55. Apothecial disks pale, pinkish to tan; thallus thin, with poorly or un-differentiated
cortex ......................................................Ionaspis
55. Apothecial disks dark gray to black; thallus with well defined cortex .........
....................................................... Aspicilia
54. Apothecia sessile and superficial, or forming pits in carbonate rocks ..........56
56. Saxicolous ....................................................57
57. On carbonate rocks ...........................................58
58. Apothecia with diffuse white pruina; epithecium gray green to dark green;
lower portion of hymenium purplish ............. Pachyphysis ozarkana
58. Apothecia epruinose; epithecium reddish brown; lower portion of hymenium
pale ......................................... Clauzadea metzleri
57. On siliceous rocks ...........................................59
59. Thallus C+, KC+ reddish (gyrophoric acid) ........ Trapelia involuta
59. Thallus C-, KC- ...........................................60
60. Ascospores thick walled, > 15 �m long and 6 �m wide ...........
............................................... Porpidia
60. Ascospores thin walled, < 15 �m long and 6 �m wide ..........61
61. Epithecium and exciple grayish or brown .................62
62. Apothecia black to gray ................ Lecidea cyrtidia
62. Apothecia pale to orange brown ........Micarea lithinella
61. Epithecium and exciple green to blue green ................63