33. Pyrenothrix] 9. PYRENOTRICHACEAE 65 



. 31. Strigula E. Fries, Vet. Akad. Handl. 323. 1821. 



Thallus crustose, forming small areas with minutely lobed margins, often partly 

 within the substratum, rudimentary, devoid of differentiation into layers, attached 

 to the substratum by hyphal rhizoids; perithecia minute, more or less immersed, 

 the wall dimidiate, the superficial portion subhemispherical to convex or depressed, 

 the ostiole minute to small; hypothecium hyaline to brownish; hymenium hyaline 

 or brownish above; paraphyses unbranched and free; asci cylindrical; spores 8, 

 hyaline, ellipsoid to fusiform, 1-3-septate, the cells cylindrical. 



The algal host is Phyllactidium, Heterothallus, or Cephaleurus. 



1. Strigula complanata Mont., in Sagra, Hist. Nat. Cub. 140. pi. 7, f. 3. 1842. 



S. elegans (Fee) Mull. Arg. S. eiegans f. hirtella Mull. Arg. S. Feei Mont. 



Thallus thin to thick, in small, round or irregular areas, frequently lobed at 

 the margin, wholly or mainly superficial, smooth or sometimes minutely ridged, 

 greenish to yellow or ashy gray; perithecia minute, 0.08-0.2 mm. across, numerous, 

 finally protruding, the superficial portion depressed-subhemispherical, black, the 

 wall dimidiate; spores ellipsoid-fusiform, 1-3-septate, 12-24 X 3-7 fi, uniseriately 

 arranged. 



On leaves of trees, from South Carolina to Florida and westward to Mississippi 

 and Texas. 



8. PYRENIDIACEAE 



Thallus crustose, membranous, scaly to squamulose and rarely distinctly 

 foliose, showing little or no differentiation into layers; perithecia more or less 

 immersed, single, the ostiole terminal. 



The algal hosts are Nostoc and Polycoccus. 



32. Hassea Zahlbr., Beih. Bot. Centralb. 13:150. 1902. 



Thallus crustose, smooth, without cortex, attached to the substratum by hyphal 

 rhizoids; perithecia minute to small, immersed, blackish, the wall dimidiate; hypo- 

 thecium hyaline; paraphyses branched and loosely arranged; asci cylindrico-cla- 

 vate; spores 8, hyaline, cylindrical, non-septate. 



The algal host is Nostoc, scattered throughout the thallus, but absent from the 

 hymenium. 



1. Hassea bacillosa (Nyl.) Zahlbr., Beih. Bot. Centralb. 13:150. 1902. 



Verrucaria bacillosa Nyl., in Hasse, Lich. South. Calif. 20. 1898. 



Thallus thin to moderately thick, olive-brownish, somewhat smooth to chinky 

 and subareolate, sometimes becoming scurfy or powdery; perithecia minute, 0.2- 

 0.3 mm. across, partly immersed, scattered, the superficial portion more or less 

 subhemispherical, black; spores long-cylindrical, straight or nearly so, 30-40 X 

 1.5-2 fi. 



On sandstone, Santa Monica Range, California. 



9. PYRENOTRICHACEAE 



Thallus taking its form from the algal host, the hyphae forming a layer about 

 the filamentous alga; perithecia more or less immersed, often with a rather long 

 neck and terminal ostiole. 



The algal host is Scytonema. 



33. Pyrenothrix Riddle, Bot. Gaz. 64:513. 1917. 



Thallus of hyaline, septate, branched hyphae, forming a layer about the fila- 

 mentous algal host; perithecia minute, pear-shaped, with terminal, inconspicuous 

 ostiole; paraphyses slender, hyaline, interwoven, and rarely branched; asci clavate; 



