140. AcarosporaJ 36. ACAROSPORACEAE 285 



ules; apothecia small, spreading, 0.5-0.8 mm. or more across, immersed 1-3 in 

 each squamule, the disk flat, black; spores spherical to ovoid, 3.5-5 X 4-6 /x. 

 On rocks, California, Arizona, and Nevada. 



5. Acarospora thelococcoides (Nvl.) Zahlbr., Cat. Lich. Univ. 5:98. 1927. 

 Lecanora thelococcoides Nyl., Lich. Lab. et Sing. 37. 1891. A. pleistospora 



(Nyl.) Hasse. A. pleiospora Zahlbr. Lecanora pleistospora Nyl. 



Thallus of small, sordid white to ashy gray, entire, subglobular, usually 

 crowded squamules, the margin coarsely white-pruinose ; apothecia minute to 

 middle-sized, 0.3-0.75 mm. across, immersed 1 in each squamule, the disk con- 

 cave, brownish black or grayish pruinose; asci ventricose; spores 24 or more, 

 spherical, 4-b jx in diameter. 



On soil, near Los Angeles, California. 



6. Acarospora scabra (Pers.) T. Fries, Scand. Lich. 1:208. 1871. 



Urceolaria scabra Pers., Ann. Wett. Ges. 2:10. 1811. A. rhagadiosa (Ach.) 

 T. Fries. Glypholecia scabra (Pers.) Mull. Arg. 



Thallus well developed, of a single white or grayish white, or rarely brownish 

 yellow squamule, centrally chinky-areolate, and marginally lobed; apothecia middle- 

 sized to large, 0.7-3 mm. across, partly immersed to almost superficial, several in 

 the squamule, round to difform, the disk flat to convex, reddish to blackish brown, 

 surrounded by a thalloid exciple, and the disk mottled with persistent lines of 

 cortical tissue, giving a falsely compound appearance; spores spherical, 2.5-3.5 ^. 



On sandstone, near the Great Falls of the Missouri River, Montana. 



7. Acarospora citrina (Tayl.) Zahlbr., Rech. Denk. Akad. Wiss. Wien. 88:28. 



1913. 

 Urceolaria citrina Tayl.; Hook., Lond. Journ. Bot. 6:158. 1847. Lecanora chry- 

 sops Tuck. Lecanora xanthoplana Nyl. A. xanthoplana (Nyl.) Jatta. Leca- 

 nora xanthoplana f. dealbata Tuck. Lecanora bella Ach. 

 Thallus well developed of lemon-yellow to white, continuous, flat to slightly 

 convex, angulate-areolate, or marginally distinct and lobed squamules; apothecia 

 minute to small, 0.2-0.6 mm. across, immersed often 4 or more in each squamule, 

 the flat to concave disk reddish to blackish brown and often irregular, an entire 

 thalloid exciple often evident; spores ovoid, 3-5 X 1.5-2 /a. 



On rocks other than calcareous, generally distributed throughout the United 

 States. 



8. Acarospora rhabarbarina Hue, Nouv. Arch. Museum V. 1:117. 1909. 

 A. bella (Nyl.) Jatta. Lecanora bella Nyl. 



Thallus composed of thin to somewhat thick, small to middle-sized, irregular, 

 bright to greenish yellow squamules, these scattered or more commonly imbricated 

 and crowded into a thick uneven crust, the outer squamules becoming lobed; apo- 

 thecia small to rarely middle-sized, 0.3-0.6 mm. across, immersed 1 or rarely 

 more in a squamule, the disk concave to flat, sometimes uneven, reddish brown to 

 brownish black, the exciple thin, colored like the thallus, becoming irregular and 

 wavy; spores ovoid to ovoid-ellipsoid, 4-6 X 1.5—2.5 /x. 



On rocks, southern California. 



9. Acarospora flava (Bell.) Trev., Riv. Per. Ace. Padova 262. 1851-52. 

 Lichen flavus Bell, Appen. Fl. Pede 261. 1792. A. chloroplana (Wahl.) Mass. 

 Thallus of conspicuous, plicate, bright lemon-colored, strongly convex, areolate- 



verrucose, or elongated and lobed squamules, the lobing especially marked toward 

 the margin ; apothecia small to middle-sized, 0.4-0.9 mm. across, immersed to 

 superficial, 1-3 or more in each squamule, the disk concave to flat, from yellow 

 to reddish and rarely blackening, the thalloid exciple entire; spores oblong-ellip- 

 soid, 4-4.5 X 1.5-2.5/*. 



On alpine rocks and at lower elevations, from Texas to Utah, and westward to 

 California and Oregon. 



