34 1. VERRUCARIACEAE [2. Trimmatothele 



2. Trimmatothele Norm., in Blombg. et Forss. Enum. Plat. 



Scand. 160. 1880. 



Thallus crustose, partly or wholly without the substratum, the superficial portion 

 warty or areolate, thin, the imbedded portion usually indicated at the surface by 

 a discoloration of the substratum, devoid of differentiation into layers; perithecia 

 minute to small, more or less immersed, the wall dimidiate, the superficial portion 

 hemispherical to convex or conical, the ostiole minute, commonly inconspicuous; 

 hypothecium hyaline to brown; paraphyses wanting; asci not plainly evident; 

 spores many, very small, ovoid or ellipsoid. 



The algal host is Pleurococcus. 



1. Trimmatothele Umbellulariae Herre, Bryologist 15:82. 1912. 



Superficial thallus very thin, widespread, dusky gray; perithecia minute to 

 small, 0.1-0.3 mm. across, partly immersed, the superficial portion black, hemi- 

 spherical to conical, the ostiole obscure; hypothecium hyaline; spores ovoid to 

 short-ellipsoid, 2.5-3 X 2-2.5 /x. 



On trees, near Berkeley, California. 



3. Thelidium Mass., Framm. Lich. 15. 1855. 



Thallus crustose, smooth to chinky, minutely granulose or areolate, seated upon 

 a poorly developed hypothallus, devoid of differentiation into layers; apothecia 

 minute to small or larger, more or less immersed, the wall dimidiate or rarely 

 complete, the superficial portion depressed to subhemispherical, the ostiole rarely 

 visible; hypothecium and hymenium hyaline; paraphyses soon becoming gelatinized 

 and indistinct; asci broadly clavate; spores 8, hyaline, 1-3-septate. 



The algal host is Pleurococcus. 

 A. Thallus minutely granulose to areolate; perithecia 



0.1-0.3 mm. across 2. T. microbolum 



A. Thallus rough to wrinkled and chinky; perithecia 



0.4-0.8 mm. across 1. T. pyrenophorum 



1. Thelidium pyrenophorum (Ach.) Mudd, Man. Brit. Lich. 294, 295. 1861. 



Verrucaria pyrenophora Ach., Lich. Univ. 285. 1810. 



Superficial thallus thin, widespread, rough, becoming wrinkled and chinky, 

 whitish to grayish; perithecia middle-sized to large, 0.4-0.8 mm. across, the super- 

 ficial portion depressed, subhemispherical-conoid, black, the wall dimidiate; spores 

 1-3-septate, oblong-ellipsoid, 22-41 X 9-16 fx. 



On rocks, Vermont, New York, Florida, Tennessee, Illinois, and Iowa. 



2. Thelidium microbolum (Tuck.) Hasse, Cont. U.S. Nat. Herb. 17:6. 1913. 



Verrucaria microbola Tuck., Gen. Lich. 269. 1872. 



Superficial thallus thin, minutely granulose to areolate, olivaceous to grayish 

 or whitish; perithecia minute to small, 0.1-0.3 mm. across, the superficial portion 

 depressed-subhemispherical, black; spores 3-septate, ovoid-ellipsoid, 23-30X10- 

 15 fi. 



On rocks, Ohio and southern California. 



OTHER SPECIES REPORTED 

 Thelidium viride (Deak.) Zahlbr. — New York. 



4. Thelidiella Fink; Hedrick, Mycologia 25:305. 1933. 



Thallus immersed in that of the lichen host and invisible; perithecia minute, 

 more or less immersed, the wall dimidiate, the superficial portion hemispherical 

 to conical, the ostiole rarely visible; hypothecium and hymenium hyaline; paraph- 

 yses soon becoming gelatinized and disappearing; asci broadly clavate, the wall 

 not much thickened in the apical region; spores 8, hyaline, 1 -septate, the cells 

 unequal. 



The algal host is Pleurococcus. 



