90 14. ARTHONIACEAE [47. Arthonia 



59. Arthonia pinastri Anzi, Comm. Soc. Critt. Ital. 1862 ! : 159. 1862. 

 Superficial thallus ashy white, thin, smooth, and disappearing; apothecia minute 



to small, 0.1-0.3 mm. across, adnate, more or less irregular, scattered or clustered, 

 the disk flat to convex, black; hypothecium tinged light brownish; hymenium hya- 

 line; spores hyaline, ovoid-ellipsoid, 3-4-septate, 16-22 X 6-9 /x. 

 On trees, near New Bedford, Massachusetts. 



60. Arthonia reniformis (Pers.) Ach., in Schrad., Journ. Bot. 1:16. 1799. 

 Opegrapha reniformis Pers., Ann. Bot. Usteri 7:31. pi. 2. f. C. 1794. 

 Superficial thallus thin, smooth, whitish to olive-green; apothecia minute to 



small, 0.01-0.3 mm. across, adnate, round to oblong, the disk flat, black; tinged 

 light brownish within; spores ovoid-ellipsoid, 5-septate, 18-23 X 5-8 fx. 

 On trees, Pennsylvania and Florida. 



61. Arthonia pruinosula Nyl., Ann. Sci. Nat. Bot. V. 7:341. 1867. 

 Superficial thallus thin, whitish to yellowish white, smooth; apothecia minute, 



0.1-0.25 mm. across, immersed, round to obscurely angular or oblong, the disk flat, 

 black, usually thinly whitish pruinose; hyaline within; asci pyriform; spores hya- 

 line to brown, ovoid-ellipsoid, 3-septate, 12-16 X 3.5-4.5 fx. 

 On trees, Florida. 



62. Arthonia polymorpha Ach., Syn. Meth. Lich. 7. 1814. 



Superficial thallus thin, smooth to slightly rough, grayish green to whitish, 

 sometimes bounded by a black line; apothecia small to middle-sized, 0.3-1 mm. 

 across, adnate, round to irregular, rarely elongated or branched, often clustered, the 

 disk flat to convex, black; tinged brown within; asci pyriform; spores hyaline or 

 tinged brownish, ovoid-ellipsoid, 3-5-septate, one end cell sometimes larger, 14-19 

 X 4.5-7.5 fi. 



On trees, Maryland, Florida, Louisiana, Illinois, Iowa, and California. 



63. Arthonia complanata Fee, Essai Crypt. 54. 1824. 



Superficial thallus thin, greenish gray to whitish, smooth to rough and chinky; 

 apothecia small to middle-sized, 0.3-0.7 mm. across, slightly immersed to adnate, 

 round, sometimes elongated to 1.2 mm., the disk flat to convex, black; tinged yel- 

 lowish brown within; asci pyriform; spores hyaline, ovoid-ellipsoid, one or both 

 end cells larger, sometimes curved, 4-6- usually 5-septate, 23-32 X 6-12 /x. 



On trees, Friday Harbor, Washington (far from its usual range). 



64. Arthonia excedens Nyl., Act. Soc. Sci. Fenn. 7:484. 1863. 



Superficial thallus thin, ashy white, smooth to slightly rough, becoming obscurely 

 chinky; apothecia middle-sized, 0.4-0.7 mm. across, or elongating to 1.5 mm., partly 

 immersed to adnate, irregular and rarely more or less branched, the disk flat to 

 convex, dark brown to black; tinged reddish brown within; spores hyaline or tinged 

 brown, ovoid-ellipsoid, 5-septate, 27-34 X 9-12 fx. 



On trees, Oregon and New York. 



65. Arthonia punctiformis Ach., Lich. Univ. 141. 1810. 



Superficial thallus thin, ashy white, usually smooth, sometimes disappearing; 

 apothecia minute, 0.1-O.2 mm. across, partly immersed to adnate, round to slightly 

 irregular, sometimes becoming oblong, the disk flat to convex, black; hypothecium 

 tinged very pale brownish; hymenium hyaline; spores hyaline, ovoid-ellipsoid, 

 3-5-septate, one end cell larger, 16-22 X 5-7 /x. 



On trees, throughout the United States. 



66. Arthonia epipastoides Nyl., Flora 56. 206. 1873. 



Superficial thallus gray to whitish, thin, smooth, becoming powdery; apothecia 

 minute, 0.05-0.1 mm. across, adnate, round to irregular or reaching 0.3 mm. long, 

 the disk flat, black; hyaline within; spores lanceolate, 1-3-septate, 16-24 X 5-7 fx. 



On trees, from New England to Florida, and westward to the Mississippi River, 

 and in California. 



