130 20. THELOTREMACEAE [70. Platygraphopsis 



exciple thick, colored like the thallus, becoming crenate; hypothecium dark brown 

 to blackish brown; spores fusiform, some slightly curved, 7-13-septate, 40-50 X 

 4.5-6 ii. 



On trees, southern California. 



70. Platygraphopsis Mull. Arg., Mem. Soc. Phys. Hist. Nat. 



Geneve 29:15. 1887. 



Thallus crustose, smooth to rough and chinky, rudimentary, showing little or 

 no differentiation into layers, attached to the substratum by hyphal rhizoids; 

 apothecia minute to small, rarely immersed to adnate, round to angular or elon- 

 gated, sometimes branched, the disk concave to flat, the exciple colored like the 

 disk, surrounded by a thin, irregular, thalloid one; hypothecium dark brown; 

 hymenium hyaline to brownish above; paraphyses branched and interwoven; asci 

 clava|f ; spores 8, hyaline to brown, dactyloid or blunt-acicular, 3-several-septate, 

 the cells cylindrical. 



The algal host is Trentepohlia. 



1. Platygraphopsis interrupta (Fee) Mull. Arg., Mem. Soc. Phys. Hist. Nat. 

 Geneve 29:15. 1887. 



Graphis interrupta Fee, Essai Crypt. 41. pi. 8, f. 1. 1824. 



Thallus thin, smooth to somewhat rough and chinky, whitish; apothecia minute 

 to small, 0.2-0.5 mm. across, immersed, round and punctiform to angular or 

 elongated and rarely becoming 1 or more times branched, the disk flat, black, the 

 proper exciple thin, black; spores hyaline to brownish, dactyloid, 3-4-septate, 

 16-22 X 5-7 fi. 



On trees, southern Florida. 



20. THELOTREMACEAE 



Thallus crustose, showing little or no differentiation, attached to the substratum 

 by hyphal rhizoids; apothecia more or less immersed to rarely superficial, single 

 or rarely somewhat united in a stroma, round, the disk usually more or less con- 

 cave, the proper exciple well developed and usually surrounded by a thalloid one. 



The algal hosts are Trentepohlia, Phyllactidium, and Heterothallus. 

 A. Paraphyses numerous, unbranched and not interwoven 

 B. Spores transversely several-septate 



C. Spores hyaline 71. Ocellularia 



C. Spores brown 72. Phaeotrema 



B. Spores transversely and longitudinally septate 



C. Spores hyaline 73. Thelotrema 



C. Spores brown 74. Leptotrema 



A. Paraphyses few, branched and interwoven 75. Gyrostomum 



71. Ocellularia Mey., Nebenstud. 327. 1825. 



Thallus crustose, smooth to minutely granulose, warty, or chinky, rudimentary, 

 commonly devoid of differentiation into layers, attached to the substratum by 

 hyphal rhizoids; apothecia minute to small or rarely middle-sized, more or less 

 immersed, the disk concave to flat, the exciple colored like the disk, thin, some- 

 times elevated, surrounded by a thicker, irregular, thalloid one; hypothecium and 

 hymenium hyaline; paraphyses unbranched, free or coherent; asci clavate to 

 broadly clavate; spores 1-8, hyaline, oblong to oblong-ellipsoid or fusiform, 

 3-many-septate, the cells lenticular. 



The algal host is Trentepohlia. 



A. Spores 3-septate 



B. Thallus greenish gray to ashy; apothecia dark flesh-colored . 6. O. micropora 

 B. Thallus ashy white to whitish or pinkish 



white; apothecia black 7. O. carnea 



