68. Lecanactis] 19. LECANACTIDACEAE 127 



19. LECANACTIDACEAE 



Thallus crustose, showing little or no differentiation, attached to the substratum 

 by hyphal rhizoids; apothecia round to irregular, immersed to adnate, the proper 

 exciple rudimentary or well developed, rarely wanting, sometimes surrounded by 

 the thallus. 



The algal host is Trentepohlia. 



A. Apothecia with irregular thalloid exciple 70. Schismatomma 



A. Apothecia with proper exciple rarely surrounded by a thin thalloid one 



B. Proper exciple well developed 68. Lecanactis 



B. Proper exciple surrounded by a thin thalloid one ... 69. Platygraphopsis 



68. Lecanactis Eschw., Syst. Lich. 14. f. 7. 1824. 



Thallus crustose, continuous or scattered, chinky, warty, or rarely areolate, 

 devoid of differentiation into layers; apothecia small to middle-sized, round to 

 more or less oblong, adnate to sessile, the disk flat to more or less convex, the 

 exciple thin to rather thick, usually black; hypothecium dark brown to black; 

 hymenium hyaline or rarely brownish above; paraphyses usually branched; asci 

 clavate to cylindrical; spores usually 8, hyaline, fusiform or oblong-fusiform, 

 3-several-septate. 



The algal host is Trentepohlia. 

 A. On trees and old wood 



B. Apothecia not more than 0.6 mm. across 1. Is. salicina 



B. Apothecia usually more than 0.6 mm. across 

 C. Thallus more or less limited and dissected 

 by a blackening hypothallus 



D. Spores 13-25 /j. in length 2. L. premnea 



D. Spores 11-17 fi in length 2. L. premnea chloroconia 



C. Thallus not limited or dissected by a 



blackening hypothallus 4. L. illecebrosa megaspora 



A. On rocks 3. L. Zahlbruckneri 



1. Lecanactis salicina Zahlbr.; Hasse, Bryologist 11:7.1906. 



Thallus thin, minutely granulose or finely scaly, ashy to sometimes yellowish 

 gray; apothecia small, 0.3-0.6 mm. across, round, subsessile, the disk flat to slightly 

 convex, densely white-pruinose to black, the exciple thin, becoming crenulate, 

 black; hypothecium dark brown; spores fusiform, 3-septate, 26-36 X 4-6.5 /x. 



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



2. Lecanactis premnea (Ach.) Arn., Flora 44:664. 1861. 

 Lecidea premnea Ach., Lich. Univ. 173. 1810. 



Thallus thin, smoothish to wrinkled, granulose or chinky, greenish to greenish 

 gray or ashy, more or less limited and dissected by a blackening hypothallus, 

 rarely disappearing; apothecia middle-sized, 0.7-1.5 mm. across, round to angular, 

 sessile, the disk flat, greenish pruinose to black, the exciple black, becoming flexu- 

 ous; hypothecium brownish black; spores fusiform-oblong, 3-septate, 13-25 X 

 3-6 ju.. 



On trees, from South Carolina to Florida, westward to Ohio and Minnesota, 

 and recurring in California. 



var. chloroconia Tuck., Gen. Lich. 194. 1872. 

 L. chloroconia Tuck., Proc. Am. Acad. 6:285. 1866. 

 The exciple thinner and the spores only 11-17 X 3-5 fi. 



On trees and old wood, from New Hampshire to South Carolina, and westward 

 to California. 



3. Lecanactis Zahlbruckneri Herre, Bot. Gaz. 43:270. 1907. 



Thallus thick, rough, pinkish to ashy gray, composed of coarse, irregular, some- 

 times folded granules; apothecia small to middle-sized, 0.5-1 mm. across, round, 

 sessile, the disk flat to convex, grayish pruinose to black, the exciple rather thick, 



