97. Thyrea] 26. PYRENOPSIDACEAE 149 



On disintegrating granite, southern California. 



The algal host as seen in material examined appears in groups as Gloeocapsa. 



4. Psorotichia Hassei Fink; Hedrick, Mycologia 25:315. 1933. 



Thallus composed of a thin, irregular, minutely granulose, olive-brown to black- 

 ish crust; apothecia minute to small, 0.15-0.6 mm. across, adnate, the disk concave 

 to slightly convex, reddish brown, the proper exciple thin and often indistinct; 

 hypothecium hyaline or tinged with yellowish brown; spores 8, oblong to ovoid- 

 ellipsoid, 16—24 X 9-12 /i, irregularly arranged. 



On soft, disintegrating sandstone among mosses, San Jacinto Mountains, Cal- 

 ifornia. 



96. Forssellia Zahlbr., in E. & P., Nat. Pfl. 1:161. 1907. 



Transforming the algal colony into a minute to small, irregular, minutely gran- 

 ulose, black body, devoid of differentiation into layers, near the edges appearing 

 to be plectenchymatous, attached to the substratum by hyphal rhizoids; apothecia 

 minute to small, immersed in wartlike elevations, the disk closed to more or less 

 open, the exciple colored like the thallus; hypothecium hyaline to brownish; hy- 

 menium hyaline; paraphyses unbranched, loose; asci clavate; spores many, hya- 

 line, subspherical to ellipsoid, non-septate. 



The algal host is Xanthocapsa. 



1. Forssellia minnesotensis Fink n. comb. 



Omphalaria minnesotensis Fink, Cont. U.S. Nat. Herb. 14:145. 1910. Thyrea 

 minnesotensis (Fink) Zahlbr. 



Transforming the algal colony into a minute to small, irregular, smooth to 

 more commonly uneven, slightly lobed, adnate to raised, rigid, black body; apothe- 

 cia minute to small, 0.3-0.5 mm. across, immersed in plainly raised wartlike ele- 

 vations of the thallus, 1 to several in each elevation, the disk punctiform, black; 

 spores subspherical to ellipsoid, 3-6 X 2-3 /a. 



On rocks, Minnesota. 



97. Thyrea Mass., Flora 39:210. 1856. 



Transforming the algal colony into a minute to small, more or less lobed and 

 branched, adnate to ascending, grayish to black body, devoid of differentiation 

 into layers, attached to the substratum at the center; apothecia minute to small, 

 immersed to becoming adnate, the disk closed to open, deeply concave to becom- 

 ing flat, the exciple colored like the thallus; hypothecium hyaline to brownish; 

 hymenium hyaline; paraphyses unbranched; asci clavate; spores 8-24, hyaline, 

 subspherical to ellipsoid, non-septate. 



The algal host is Xanthocapsa. 



A. On rocks 



B. Thalloid body grayish pruinose or black 1. T. pulvinata 



B. Thalloid body black but not pruinose 



C. Apothecia minute, 0.0S-0.1S mm. across 4. T. pyrenoides 



C. Apothecia minute to small, 0.2-0.5 mm. across . . . . 3. T. Demangeonii 

 A. On trees 2. T. Girardi 



1. Thyrea pulvinata (Schaer.) Mass., Flora 39:211. 1856. 



Parmelia stygia var. pulvinata Schaer., Lich. Helv. Spic. sec. 11. 544. 1842. Om- 

 phalaria pulvinata (Schaer.) Nyl. 



Transforming the algal colony into a small, ascending to suberect, pulvinately 

 lobed, marginally wavy to more or less deeply lobed, grayish pruinose or black 

 body; apothecia minute to small, 0.2-0.5 mm. across, immersed to adnate, borne 

 along the margins of the lobes, the disk almost closed to open, blackish to lighter, 

 the algoid exciple very thin, colored like the thallus or lighter; spores 8, short- 

 ellipsoid, 9-12 X 5-6/i. 



On rocks, New England and New York, and westward to Minnesota and 

 Nevada. 



