47. Arthonia] 14. ARTHONIACEAE 91 



67. Arthonia radiata (Pers.) Ach., Vet. Akad. Nya Handl. 131. 1808. 

 Opegrapha radiata Pers., Ann. Bot. Usteri 7:29. pi. 2, f. 33. 1794. A.astroidea 



Ach. Opegrapha atra var. macularis E. Fries. A. radiata var. Swartziana 

 (Ach.) Almq. A.astroidea var. Swartziana (Ach.) Nyl. 

 Superficial thallus thin, greenish gray to whitish or brownish, smooth to 

 slightly rough, rarely bordered by a dark line; apothecia small to middle-sized or 

 larger, 0.3-1.5 mm. across, irregular to elongated, stellately branched, partly 

 immersed to subadnate, often clustered, the disk flat to slightly convex, black; 

 brownish within; hypothecium darker; asci pyriform; spores hyaline, ovoid- 

 ellipsoid, 3-septate, 12-19 X 4-6 /x. (Plate 3 a.) 

 On trees, throughout the United States. 



f. angustata Vainio, Med. Soc. Faun. Fl. Fenn. 10:157. 1883. 

 Apothecia linear, sometimes elongated to 1 mm., commonly curved, sometimes 

 branched. 



On trees, southern California. 



var. epipastoides (Nyl.) A. L. Smith, Brit. Lich. 2:216. 1911. 



A.astroidea var. epipastoides Nyl., Not. Sallsk. Faun. Flor. Fenn. 5:259. 1881. 



Superficial thallus ashy white, thin, smooth; apothecia minute to small, 0.1- 

 0.3 mm. across, partly immersed to adnate, slightly irregular, sometimes clustered, 

 the disk flat to convex, black; tinged pale yellowish within; asci narrowly pyri- 

 form; spores ovoid-ellipsoid, 3-septate, 13-16 X 3-5 fi. 



On trees, Sanford, Florida. 



68. Arthonia subastroidella Nyl., Flora 68:312. 1885. 



Superficial thallus thin, smooth, ashy, often disappearing; apothecia minute 

 to small, 0.2-0.8 mm. across, immersed to subadnate, round to irregular and ob- 

 scurely stellate, or long, reaching 1 mm., often in clusters, the disk flat, dull 

 black; hyaline within; spores hyaline, ovoid-ellipsoid, 3-septate, 12-18 X 4-5 fi. 



On trees, New Bedford, Massachusetts. 



69. Arthonia quintaria Nyl., Flora 68:312. 1885. 



Superficial thallus thin, smooth, grayish to ashy white; apothecia minute to 

 small, 0.1-0.3 mm. across, immersed, sometimes clustered, irregular to substellate, 

 the disk flat to convex, black; tinged pale yellowish within; spores hyaline, ovoid- 

 ellipsoid, 3-7-septate, 18-25 X 6-10 /i. 



On trees, from Massachusetts to Florida. 



70. Arthonia xylographica Nyl., Flora 68:312. 1885. 



Superficial thallus thin, ashy white, smooth; apothecia minute to small, 0.2- 

 0.5 mm. across or reaching 1.3 mm. in length, adnate, round, irregular, or elongated 

 and often curved or branched, sometimes surrounded by a thalloid veil, the disk 

 slightly convex, blackish; hyaline to pale brownish within; asci pyriform; spores 

 ovoid-ellipsoid, 3-septate, 12-15 X 4-5 fi. 



On trees, New Bedford, Massachusetts. 



71. Arthonia Hamamelidis Nyl., Flora 68:447. 1885. 



Thallus very thin, indicated by a greenish gray to whitish coloration, often 

 entirely absent above the substratum; apothecia small to middle-sized, 0.3-0.5 mm. 

 or elongated to 1.5 mm. in one direction, irregular, and usually more or less 

 branched, slightly immersed to adnate, the disk flat and black; brownish within 

 with a dark hypothecium; spores hyaline, oblong-ellipsoid, 3-septate, 10-14 X 



3.5-4.5 /t. 



On Hamamelis virginica, near New Bedford, Massachusetts. Possibly too near 

 A. astroidea Ach. 



72. Arthonia torulosa Fee, Essai Crypt. 55. pi. 24, f. 1. 1824. 



Superficial thallus thin, smooth, greenish gray to pale olive-green, surrounded 

 by a dark line; apothecia minute, 0.05-0.2 mm. across, immersed, irregular and 



