82 14. ARTHONIACEAE [47. Arthonia 



2. Arthonia incarnata Kullh. Almq., Kgl. Svensk. Vet. Akad. Handl. 17:18. 1880. 



Superficial thallus thin, greenish gray to ashy white, smooth to slightly rough; 

 apothecia minute to small, 0.1-0.3 mm. across, adnate, round to slightly irregular, 

 the disk convex, reddish brown and darker; tinged pale brownish within; asci 

 narrowly pyriform; spores hyaline, ovoid-ellipsoid, 2-septate, one end cell larger, 

 11-16 X 4.5-6.5/a. 



On trees, White Mountains, New Hampshire. 



3. Arthonia lurida Ach., Lich. Univ. 143. 1810. 



Superficial thallus smooth, greenish gray to whitish, thin and disappearing; 

 apothecia minute to small, 0.1-0.4 mm. across, adnate, round to somewhat ir- 

 regular, the disk flat to convex, brownish black; hypothecium reddish; hymenium 

 lighter; spores hyaline, ovoid-ellipsoid, 1-septate, one end cell larger, 10-15 X 

 4-5 /i. 



On trees, New England, New York, and California. 



4. Arthonia floridana Willey, Int. Stud. Lich. Suppl. 52. 1887. 



Thallus ashy, very thin, smooth, surrounded by a thin dark line; apothecia 

 minute, 0.1-0.2 mm. across, immersed more or less in the substratum, round to 

 oblong or irregular, the disk flat to slightly convex, dark brown to black; hypothe- 

 cium brown; hymenium hyaline; asci pyriform; spores hyaline, fusiform-ovoid, 

 1-septate, 16-20 X 5.5-7.5 fi. 



On trees, Florida. 



5. Arthonia ochrodiscodes Nyl., Lich. Jap. 107. 1890. 



Thallus thin, ashy white, smooth; apothecia minute to small, 0.1-0.6 mm. 

 across, adnate, round, the disk flat to convex, ochre-yellow to blackish; tinged 

 brownish within; spores 1-septate, oblong-ovoid, constricted at the septum, hyaline, 

 14-17 X 6-8/1. 



On trees, Florida. Very similar to A floridana. 



6. Arthonia lecanactidea Zahlbr., Beih. Bot. Centralb. 13:155. 1902. 



Superficial thallus thin to moderately thick, creamy to ashy white, rough, 

 obscurely chinky; apothecia minute to small, 0.2-0.5 mm. across, adnate, round 

 to slightly irregular, the disk flat to convex, brownish gray to black; tinged pale 

 brownish within; asci pyriform; spores hyaline, ovoid-ellipsoid, 1-septate, one cell 

 slightly larger, 10-15 X 3.5-4.5 /x. 



On trees, southern California. 



7. Arthonia impallens Nyl., Flora 68:448. 1885. 



Superficial thallus thin, whitish, smooth; apothecia minute to small, 0.08-0.2 

 mm. across, often elongated to 0.7 mm., partly immersed to adnate, linear, or more 

 or less branched, the disk flat, pale yellowish to slightly brown; hyaline within; 

 asci pyriform; spores hyaline, ovoid-ellipsoid, 1-3-septate, one end cell larger, 

 11-14X3-4/1. 



On holly, New Jersey. 



8. Arthonia ochrolutea Nyl., in Willey, Syn. Arth. 4. 1890. 



Superficial thallus thin, dull white to pale yellowish, smooth; apothecia numer- 

 ous, sometimes coalescing, small, 0.1-0.4 mm. across, adnate, irregular and often 

 elongated, reaching 1 mm. or more in length, often surrounded by a thalloid veil, 

 the disk flat, pale yellow; tinged pale yellowish within; spores hyaline, ovoid- 

 ellipsoid, 3-septate, 10-15.5 X 3-4 /i. 



On trees, Florida. 



9. Arthonia gyalectoides Mull. Arg., Flora 69:128. 1886. 



Superficial thallus thin, ashy white, becoming powdery, smooth to rough and 

 chinky; apothecia small to middle-sized, 0.4-0.9 mm. across, adnate, round-flexuous 

 to irregular, or finally lobed, the disk concave to flat, flesh-colored to brownish 



