92 14. ARTHONIACEAE [47. Arthonia 



finally stellate, the disk flat to slightly convex, brownish black; hypothecium dark 

 brown; hymenium light brown; asci globose-ovoid; spores hyaline, oblong-ovoid, 

 5-septate, one or rarely both end cells larger, 13-16 X 5-6 /x. 

 On trees, Louisiana. 



73. Arthonia asteriscus Mull. Arg., Bull. Herb. Boiss. 3:49. 1895. 

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



minute to small, 0.2-0.5 mm. across, sometimes elongated to 0.6 mm., partly im- 

 mersed to adnate, irregular to obscurely stellate, the disk flat to convex, black; 

 hyaline or blackening within; asci pyriform; spores hyaline, oblong-ovoid, 4-5- 

 septate, 14-17 X 4.5-6.5 //.. 

 On trees, Louisiana. 



74. Arthonia galactitella Nyl., in Hasse, Cont. U.S. Nat. Herb. 17 1 :18. 1913. 

 Superficial thallus thin, ashy white to cream-colored, smooth, becoming finely 



powdered; apothecia minute, 0.1-0.2 mm. across, partly immersed to adnate, round 

 to irregular, or oblong, reaching 0.3 mm. long, the disk flat, black, more or less 

 whitish pruinose; hyaline within; spores hyaline, ovoid-ellipsoid, 3-septate, 14-20 X 

 5-7.5 ii. 



On trees, southern California. 



75. Arthonia stictella Stizenb., in Hasse, Cont. U.S. Nat. Herb. n x :20. 1913. 

 Superficial thallus thin, dull white, becoming obscurely scurfy; apothecia 



minute, elongated, and parallel, 0.1-0.2 X 0.4-1 mm., immersed to subadnate, the 

 disk flat to convex, black; hyaline within; asci pyriform; spores hyaline, ovoid- 

 ellipsoid, 5-septate, 18-25 X 6-7 /x. 



On trees, Catalina Island, California. 



76. Arthonia platygraphidea Nyl., Act. Soc. Sci. Fenn. 7:483. 1863. 

 Superficial thallus thin, whitish to ashy, smooth to rough, surrounded by a 



brownish black line; apothecia small to middle-sized, 0.3-0.9 mm. across, often 

 elongated to 1.5 mm., immersed in a thalloid veil or adnate, round to slightly 

 irregular, the disk flat to convex, brownish black to black; tinged faintly reddish 

 within; spores fusiform, hyaline or tinged brown, 11-13-septate, 52-70 X 1 5—2 1 yu.. 

 On trees, Florida. 



77. Arthonia phaeobaea Norm., Flora 52:525. 1869. 

 Segestrella phaeobaea Norm., Scrip. Soc. Reg. Sci. Norv. 5:367. 1868. A. para- 



lia Nyl. A. atlantica Willey in Herb. 



Superficial thallus thin to moderately thick, slightly rough, greenish gray to 

 brownish; apothecia minute, 0.15-0.25 mm. across, adnate, round to somewhat 

 irregular, numerous but seldom clustered, the disk convex, brownish black; hya- 

 line within; spores hyaline, ovoid-ellipsoid, 3-5-septate, 17-25X6-8.5/*, possibly 

 becoming submuriform. 



On rocks, near Eastport, Maine. 



OTHER SPECIES REPORTED 



Arthonia atrata (Fee) Mull. Arg. — Florida. 

 Arthonia caudata Willey — Massachusetts. 

 Arthonia didyma Koerb. — New Hampshire. 

 Arthonia erupta Nyl. — Florida and Texas. 

 Arthonia oxytera Nyl. — Florida and Texas. 

 Arthonia septiseptella Nyl. — Alabama. 

 Arthonia subminutula Nyl. — Massachusetts. 

 Arthonia tetramera (Stizenb.) Hasse — California. 

 Arthonia varians (Dav.) Nyl. — Massachusetts and New York. 

 Arthonia vernans Willey — Florida. 



Celidium stictarum (De Not.) Tul. (Not a lichen, although treated as an Arthonia 

 by some workers.) — New Hampshire. 



