94 14. ARTHONIACEAE [48. Arthothelium 



4. Arthothelium spectabile Mass., Ric. Lich. 54. f. 101. 1852. 



Arthonia spectabilis (Mass.) Flot., in E. Fries, Lich. Eur. 371. 1831. 



Superficial thallus moderately thick, whitish or grayish, smooth to rough, rarely 

 subareolate, occurring in small, round areas, or more commonly widespread and 

 irregular, bordered and more or less dissected by black lines; apothecia small to 

 middle-sized or larger, 0.3-1.5 mm. across, variously irregular, immersed to adnate, 

 the disk flat to convex, obscurely white-pruinose, or more commonly black, tinged 

 brown within; asci pyriform; spores oblong-ellipsoid, hyaline to pale brown, 5-9- 

 septate transversely and 2-5-septate longitudinally, 26-38 X 12-20 fx. 



On trees, throughout the United States. 



5. Arthothelium pruinascens Zahlbr., Bull. Torr. Club 27:646.647. 1900. 



Superficial thallus thin, dirty white to greenish or yellowish gray, smooth to 

 rough, round to widespread and irregular; apothecia small, 0.15-0.35 mm. across, 

 immersed to adnate, round to irregular, the disk flat, white-pruinose; hyaline 

 within; asci pyriform; spores oblong-ellipsoid, 5-7-septate transversely and 1-3- 

 septate longitudinally, 17-22 X 8-12 li. 



On trees, Santa Monica Range, California. 



Near A. spectabile according to Zahlbruckner. 



6. Arthothelium orbilliferum (Almq.) Hasse, Cont. U. S. Nat. Herb. 17:22. 1913. 



Arthonia orbillijera Almq., Kgl. Svensk. Vet. Akad. Handl. 17:41. 1880. 



Superficial thallus thin, whitish to lead-gray, smooth to slightly rough; apothe- 

 cia minute to small, 0.2-0.5 mm. across, immersed to adnate, sometimes clustered, 

 the disk round to more or less irregular, convex, black; hyaline within; asci pyri- 

 form; spores oblong-ovoid, hyaline, 5-7-septate transversely and 1-3-septate 

 longitudinally, 20-28 X 10-17 /x. 



On trees, Santa Monica Range and Catalina Island, California. 



7. Arthothelium anastomosans (Ach. ) Arm, in Rehm, Rabh. Krypt.-Fl. 



Deutsch. ed. 2. 1:442. 1891. 



Arthonia radiata var. anastomosans Ach., Lich. Univ. 146. 1810. 



Superficial thallus thin, whitish, smooth to slightly rough, in small round 

 patches, to irregular and covering larger areas; apothecia small to middle-sized or 

 larger, 0.2-1.2 mm. across, irregular to branched and often distinctly radiate, often 

 in clusters, the disk black throughout or white-pruinose toward the margins; 

 asci ovoid-pyriform; spores hyaline, ovoid-ellipsoid, 5-9-septate transversely and 

 3-5-septate longitudinally, 17-23 X 7-8.5 /x. 



On trees, southern California. 



8. Arthothelium abnorme (Ach.) Mull. Arg.. Flora 63:287. 1880. 

 Opegrapha abnormis Ach., Lich. Univ. 259. 1810. Arthonia abnormis (Ach.) 



Nyl. 



Thallus thin, white to whitish, in small, round to irregular patches; apothecia 

 small to middle-sized, round to irregularly angular or sometimes stellate, the disk 

 black; asci pyriform to almost spherical; spores 4-8, hyaline, ovoid-ellipsoid, 

 4-8-septate transversely and 1-3-septate longitudinally, 14-20 X 7.5-10 ll. 



On trees, California. 



No specimen has been seen, the description adapted from Herre, Bryologist 

 15:83, 84. 1912. 



9. Arthothelium taediosum (Nyl.) Mull. Arg., Flora 63:287. 1880. 



Arthonia taediosa Nyl., Ann. Sci. Nat. IV. 3:171. 1855. 



Thallus rather thin, smooth to slightly rough, whitish, limited more or less 

 by a black line; apothecia minute to small, 0.1-0.25 mm. across, or elongated to 

 more than 1 mm. in one direction, immersed, irregularly linear and becoming 

 branched, often clustered, the disk dirty black or thinly white-pruinose; asci 

 pyriform; spores hyaline to finally brown, ovoid-oblong, 5-9-septate transversely 

 and 2-5-septate longitudinally, 27-35 X 11-15 ll. 



