47. Arthonia] 14. ARTHONIACEAE 83 



black, or white-pruinose; hyaline or tinged faintly brownish within; asci pyriform; 

 spores hyaline, ovoid-ellipsoid, 4-5-septate, one end cell larger, 16-22 X 6-8 /u.. 

 On trees, southern California. 



10. Arthonia fissurina Nyl., Flora 68:447. 1885. 



Superficial thallus thin, dull white, smooth; apothecia small to middle-sized, 

 0.2-0.8 X 0.1-0.2 mm., immersed, elongated and somewhat irregular, the disk 

 slightly concave, brownish, sometimes showing a thalloid veil; hyaline or tinged 

 pale brownish within; asci pyriform; spores ovoid-ellipsoid, 7-11-septate, 24-32 

 X8-11/*. 



On trees, Florida. 



11. Arthonia pyrrhula Nyl.. Flora 68:447. 1885. 



Superficial thallus thin, ashy whitish, smooth to slightly rough; apothecia 

 minute to small, 0.2-0.4 mm. across, immersed, irregular to elongated and reach- 

 ing 1 mm. long, sometimes clustered, the disk flat, reddish; tinged pale reddish 

 within; spores hyaline, ovoid-ellipsoid. 5-7-septate, 30-50 X 14-18 ;u.. 



On trees, from New England to Florida. 



12. Arthonia gregaria (Weig.) Koerb., Syst. Lich. Germ. 291. 1855. 



Sphaeria gregaria Weig., Obs. Bot. 43. 1772. A. gregaria var. obscura Koerb. 

 A. cinnabarina (DC.) Walk. 



Superficial thallus thin, gray to whitish, smooth; apothecia minute to small, 

 0.1-0.3 mm. across, sometimes elongating to 1 mm., partly immersed, irregular to 

 oblong, or even stellate, often clustered, the disk slightly concave to convex, reddish 

 brown to blackish and often whitish or crimson-pruinose; hyaline within; asci 

 pyriform; spores hyaline to light brownish, ovoid-ellipsoid, 3-5-septate, one end 

 cell larger, 12-22 X 5-8 /x. 



On trees, generally distributed throughout the United States, 

 var. adspersa (Mont.) Mull. Arg., Flora 71: 524. 1888. 



Ustalia adspersa Mont., Ann. Sci. Nat. Bot. 18:278. 1842. 



Apothecia violet-brown; spores 4-septate, 15-24X7-9/*. 



On trees, Louisiana. 



13. Arthonia ochrocincta Willey, Syn. Arth. 8. 1890. 



A. ochrocincta Nyl., Flora 69:104. 1886. (nomen nudum). 



Thallus thin, gray to whitish, smooth or slightly rough; apothecium minute to 

 small, 0.15-0.25 X 0.3-1 mm., adnate, subrotund to irregular, or elongated and 

 curved, sometimes clustered, the disk flat to somewhat convex, dull black or ob- 

 scurely whitish pruinose, bordered by an ochre-red margin; tinged pale yellowish 

 within; asci pyriform; spores hyaline, ovoid-ellipsoid, 3-5-septate, one and rarely 

 both end cells larger, 18-23 X 4-6 /x. 



On trees, Florida. 



Our specimens were determined by Merrill. Nylander gave no description, but 

 merely cited Tuckerman's exsiccatus No. 134. 



14. Arthonia Ravenelii Tuck., in Willey, Int. Stud. Lich. Suppl. 53. 1887. 

 Superficial thallus thin, whitish, smooth to obscurely rough; apothecia minute 



to small, 0.5-1.5 X 0.1-0.2 mm., immersed, elongated, usually curved and rarely 



branched, the disk flat, reddish brown to black; tinged faintly reddish within; 



spores hyaline, ovoid-ellipsoid, 3-7-septate, one end cell larger, 20-28 X 7-10 /x. 



On trees, Louisiana and Texas. Differs slightly from material from Mexico. 



15. Arthonia viridicans Willey, Syn. Arth. 10. 1890. 



Superficial thallus thin, grayish green, often intersected by black lines; apothecia 

 small, 0.2-0.4 mm. across, adnate, round to irregular or oblong, the disk slightly 

 convex, brown to dull black; hyaline within; spores hyaline, ovoid-ellipsoid, 3- 

 septate, 12-15 X 4-6 fx. 



On trees, Texas. 



