56 10. MYCOPORACEAE [ 34. Mycoporellum 



spores 8, dark brown, ellipsoid, transversely and longitudinally septate, irregularly 

 arranged. 



The algal host is Scytonema. 



1. Pyrenothrix nigra Riddle, Bot. Gaz. 64:513-15. 1917. 



Thallus composed of hyaline, septate, flexuous, branched hyphae, 3-4 \x. thick 

 and closely applied to the surface of the brownish black, branched algal host; 

 perithecia minute, 0.15-0.25 mm. across, blackish, immersed to closely adnate, the 

 neck short and thick, the ostiole minute and indistinct, the wall thin but com- 

 plete, plectenchymatous; spores blackish brown, oblong to broadly ellipsoid, 

 4-5-septate transversely and becoming 1-septate longitudinally, 17-20 X 6-9 fi. 



Growing over Scytonema sp., Florida. 



10. MYCOPORACEAE 



Thallus crustose, partly within the substratum, devoid of differentiation into 

 layers; perithecia more or less immersed, united by complete or incomplete walls 

 to form a more or less compound perithecium, each hymenium with a terminal 

 ostiole. 



The algal hosts are Palmella and Trentepohlia. 



A. Spores transversely several-septate 34. Mycoporellum 



A. Spores transversely and longitudinally septate 35. Mycoporum 



34. Mycoporellum Mull. Arg., Revue Mycol. 6:14. 1884. 



Thallus crustose, smooth to slightly rough, rudimentary, partly or wholly 

 within the substratum, devoid of differentiation into layers; perithecia minute to 

 small, more or less immersed to adnate, the wall dimidiate or rarely complete, the 

 superficial portion round to oblong or irregular, convex to flat or depressed, the 

 ostioles several to many, round to more or less irregular; hypothecium hyaline to 

 brown; hymenium hyaline or brownish above; paraphyses wanting or poorly de- 

 veloped and branched and interwoven; asci ovoid-clavate, enlarged toward the 

 apices and the apical wall somewhat thickened; spores 8, hyaline to rarely brown, 

 ovoid-ellipsoid to oblong or ellipsoid, 1-3 or rarely 5-septate, the cells cylindrical, 

 often unequal. 



The algal host is Trentepohlia. 



A. Perithecia reaching 1mm. or more across; ostioles many 



B. Spores 1-3-septate, 16-21 /x in length 3. M. californicum 



B. Spores 1-septate, 18-28 n in length 2. M.Hassei 



A. Perithecia not more than 0.6mm. across; ostioles several 



B. Spores 1-3-septate 4. M. difforme 



B. Spores 1-septate 1. M.sparsellum 



1. Mycoporellum sparsellum (Nyl.) Mull. Arg., Revue Mycol. 6:14. 1884. 

 Mycoporum sparsellum Nyl., Ann. Sci. Nat. Bot. V. 7:343. 1867. 



Thallus very thin, ashy, smooth to slightly rough, or disappearing; perithecia 

 minute to small, 0.3-0.6 mm. across, adnate, often irregular, dull black, ostioles 2 

 or 3 to several; spores 1-septate, slightly constricted, ovoid-ellipsoid, sometimes 

 slightly curved, 16-24 X 6-9 /x. 



On trees, Florida and southern California. 



2. Mycoporellum Hassei Zahlbr., in Hasse, Cont. U.S. Nat. Herb. 17:13, 14. 



1913. 



Thallus very thin, becoming squamulose, whitish to ashy white; perithecia 

 small to middle-sized, 0.4-1 mm. across, slightly immersed to adnate, flat to slight- 

 ly convex, often irregular or elongated, dull black, ostioles 14-18; spores 1-septate, 

 oblong, 18-28 X 7.5-10 fx, one cell narrower and more pointed. 



On trees, Catalina Island, California. 



