44 4. PYRENULACEAE [ 14. Microthelia 



2. Pyrenothamnia Brandegei (Tuck.) Zahlbr., Cat. Lich. Univ. 1:251. 1921. 



Staiirothele Brandegei Tuck., Bull. Torr. Club 11:26. 1884. 



Thallus composed of very short, erect, round, finger-shaped stalks, soon crowded 

 and dilated into a warty, brown to blackish, more or less irregular crust; peri- 

 thecia minute, 0.15-0.25 mm. across, immersed, the ostiole closed, surrounded by 

 a depressed, sometimes lighter colored area, the wall complete, hyaline to slightly 

 tinged with brown; spores 1, brown to blackish, broadly ellipsoid, 7-11 -septate 

 transversely and 2-4-septate longitudinally, 26-50 X 20-24 /x. 



On rocks, Washington. 



4. PYRENULACEAE 



Thallus crustose, partly or wholly within the substratum or rarely immersed 

 in the lichen host, devoid of differentiation into layers; perithecia more or less 

 immersed, spherical to subspherical, single or clustered, the ostiole terminal; 

 paraphyses distinct, unbranched and free or branched and more or less interwoven. 



The algal host is Trentepohlia. 



A. Paraphyses branched and netlike interwoven 

 B. Spores transversely several-septate 



C. Spores with lenticular cells 18. Pseudopyrenui.a 



C. Spores with cylindrical cells 



D. Spores brown 14. Microthelia 



D. Spores hyaline 



E. Spores ovoid to oblong, 1-S-septate IS. Arthopyrenia 



E. Spores acicular to threadlike, 1-several-septate . . 16. Leptorhaphis 



B. Spores transversely and longitudinally septate 17. Polyblastiopsis 



A. Paraphyses unbranched, free 

 B. Spores with cylindrical cells 



C. Asci soon disappearing 21. Belonia 



C. Asci remaining 



D. Spores many in each ascus 22. Thelopsis 



D. Spores 1-8 in each ascus 



E. Spores transversely several-septate, hyaline 19. Porina 



E. Spores transversely and longitudinally septate . . 20. Clathroporina 

 B. Spores with lenticular cells 



C. Spores transversely 1-5-septate, brown 



D. Thallus imbedded in that of lichen host 24. Pyrenulella 



D. Thallus not imbedded 23. Pyrenula 



C, Spores transversely and longitudinally septate, brown 25. Anthracothecixjm 



14. Microthelia Koerb., Syst. Lich. 372. 1855. 



Thallus forming a thin, smooth to minutely granulose crust over the substratum, 

 partly or wholly within the substratum, devoid of differentiation into layers; 

 perithecia minute to small, more or less immersed, the superficial portion flat to 

 convex or hemispherical, the ostiole minute to small, often depressed, the wall 

 dimidiate or complete; hypothecium brownish to dark brown; hymenium hyaline 

 or brownish above; paraphyses branched and interwoven; asci clavate to cylindrico- 

 clavate; spores commonly 8, brown, oblong-ellipsoid, ellipsoid or slipper-shaped, 

 1-3- or rarely 5-septate, the cells cylindrical 



The algal host is Trentepohlia. 



A. On trees 



B. Apothecia round, not more than 0.5 mm. across 

 C. Spores reaching 20-30 /* in length 



D. Thallus more or less bordered and intersected 



by black lines 5. M. Willeyana 



D. Thallus more or less bordered but not intersected 



by black lines 2. M. thelena 



C. Spores not more than 18/t in length 



D. Spores 1-septate 1. M. micula 



D. Spores becoming 2-3-septate 1. M. micula quadriloculata 



