140. Acarospora ] 36. ACAROSPORACEAE 283 



spores numerous, minute, hyaline, oblong, ellipsoid or spherical, non-septate, or 

 rarely becoming 1 -septate. 



The algal host is Pleurococcus or Protococcus. 



A. Apothecia small, not more than 0.5 mm. across; the 



exciple granulose 1. M. constans sublecideina 



A. Apothecia larger, reaching 1mm. across; the exciple 



becoming crenulate 1. M. constans 



1. Maronea constans (Nyl.) Hepp, Flecht. Eur. No. 771. 1860. 



Lecanora constans Nyl., Mem. Soc. Imp. Sci. Nat. Cherb. 3:199. 1855. Rino- 

 dina constans (Nyl.) Tuck. 



Thallus thin, granulose, greenish gray to brownish or ashy, the granules minute, 

 becoming wartlike, commonly forming small, round to irregular areas; apothecia 

 small to middle-sized, 0.4-1 mm. across, sessile, the disk flat, brownish black to 

 black, the exciple thick, colored like the thallus, becoming crenulate; hypothecium 

 hyaline to yellowish; asci clavate; spores numerous, minute, oblong, hyaline, non- 

 septate to becoming 1-septate, 3-6 X 1.5-2.5 jx. 



On trees, from New England to South Carolina, and westward to Alabama and 

 Illinois. 



var. sublecideina Zahlbr. ; Hasse, Bryologist 16:1,2. 1913. 

 Apothecia usually smaller than in the species, 0.3-0.5 mm. across, the exciple 

 thin, granulose, colored like the thallus, sometimes almost disappearing. 

 On trees, southern California. 



140. Acarospora Mass., Ric. Lich. 27. f. 43-46. 1852. 



Thallus squamulose, the squamules forming areoles, especially toward the center, 

 frequently lobed toward the margin, commonly closely adnate and plectenchy- 

 matous throughout, whitened (dealbate) conditions occurring in some of the species, 

 and often segregated as subspecies; apothecia minute to middle-sized or larger, 

 immersed or infrequently becoming superficial, 1-3 or more to each areole, a 

 thalloid exciple frequently differentiated; hymenium and hypothecium commonly 

 hyaline; paraphyses hyaline, usually unbranched, coherent and semidistinct; asci 

 frequently becoming inflated-ventricose; spores minute, non-septate, spherical to 

 ellipsoid, numerous. (Plate 28.) 



The algal host is Protococcus. 



A. Thallus yellow or white, rarely clay-colored 

 B. On soil 



C. Thallus white or whitish pruinose 



D. Apothecia brownish black or gray-pruinose . . . 5. A. thelococcoides 



D. Apothecia blackish red 3. A. reagens 



C. Thallus sulphur-colored or finally dirty white 1. A. Schleicheri 



B. On rocks 



C. Thallus bright yellow 

 D. Thallus squamulose 



E. Apothecia yellow to reddish or rarely blackening . . . . 9. A. flava 

 E. Apothecia reddish brown to brownish black . . . 8. A. rhabarbarina 



D. Thallus areolate 7. A. citrina 



C. Thallus white, grayish, or rarely brownish 

 D. Spores spherical 



E. Apothecia 0.4-1.2 mm. across 2. A. saxicola 



E. Apothecia 0.7-3 mm. across 6. A. scabra 



D. Spores subspherical to ovoid or ellipsoid 



E. Thallus of irregular squamules 4. A. peltasticta 



E. Thallus of short, branched stipes 11. A. thermophila 



A.. Thallus greenish gray to brown or darker 



B. Thallus areolate, rarely wanting or of branched stipes 

 C. Thallus not areolate 



D. Thallus wanting 24. A. glaucocarpa depauperata 



D. Thallus of branched stipes 27. A. thamnina 



