74. Leptotrema ] 20. THELOTREMACEAE 133 



2. Thelotrema interpositum (Nyl.) Mull. Arg., Flora 64:526. 1881. 



Ascidintn interpositum Nyl., Ann. Sci. Nat. Bot. IV. 19:335. 1863. 



Thallus thin, rough, minutely warty, becoming chinky, greenish gray to dull 

 white ; apothecia small to middle-sized, 0.4-0.8 mm. across, slightly immersed to 

 superficial, the disk flat, black, sometimes whitish pruinose, the proper exciple 

 thick, black, surrounded by a thick, somewhat irregular, thalloid one; spores 1, 

 hyaline to slightly brown, fusiform, 29-39-septate transversely and 3-7-septate 

 longitudinally, 128-180 X 28-42 //,. 



On trees, Georgia, Florida, Alabama, Louisiana, and Texas. 



OTHER SPECIES REPORTED 

 Thelotrema compunctum (Smith) Nyl. — Louisiana and South Carolina. 

 Thelotrema Halei (Tuck.) Nyl. — Louisiana. 

 Thelotrema lepadodes Tuck. — Florida. 



74. Leptotrema Mont. & Bosch., Lich. Jav. 57. 1855. 



Thallus crustose, smooth to warty, areolate, or chinky, partly within the sub- 

 stratum, commonly devoid of differentiation into layers, attached to the substratum 

 by hyphal rhizoids; apothecia minute to small or middle-sized, more or less im- 

 mersed to superficial, the disk closed to more or less open, concave to flat, the 

 exciple thin, colored like the disk, surrounded by a thicker, sometimes disappearing, 

 thalloid one; hypothecium hyaline; hymenium hyaline or brownish above; paraph- 

 yses unbranched, free; asci clavate to broadly clavate; spores 1-8, brown, oblong 

 to ellipsoid or ovoid-ellipsoid, transversely and longitudinally septate. 



The algal host is Trentepohlia. 



A. Thallus thin, smooth to slightly rough, wrinkled, or warty 

 B. Apothecia not more than 0.6 mm. across 



C. Apothecia minute, not more than 0.2 mm. across . . 6. L. laeviusculum 



C. Apothecia 0.2-0.6 mm. across 



D. Thallus greenish gray to ashy 7. L. glaucescens 



D. Thallus greenish to yellowish 2. L. Ravenelii 



B. Apothecia reaching 0.8-1 mm. across 



C. Spores 1, 80-135 /j. in length 3. L. monosporum 



C. Spores 8, 14-26 fi in length 4. L. Wightii 



A. Thallus thin to thick, granulose or bearing minute coralloid branchlets 



B. Thallus granulose 1. L. Auberianum 



B. Thallus bearing minute coralloid branchlets 



C. Thallus rough, sometimes crumbling; apothecia 



0.6-1.2 mm. across 5. L. santense 



C. Thallus smooth to rough ; apothecia 0.8-2 mm. across . 8. L. heterosporum 



1. Leptotrema Auberianum (Mont.) Fink n. comb. 



Thelotrema Auberianum Mont., in Sagra, Hist. Nat. Cub. 163. pi. 8, f. 2. 1842. 

 Phaeotrema Auberianum (Mont.) Mull. Arg. 



Thallus thin, chinky, somewhat wrinkled, becoming minutely granulose, greenish 

 gray to ashy brown; apothecia small to middle-sized, 0.4-0.8 mm. across, immersed 

 to almost superficial, the disk black, often covered by a perforate, whitish veil, 

 the proper exciple thin, brown, more or less exposed by the disappearing of the 

 thicker thalloid one; spores 8, oblong-ellipsoid, 3-5-septate transversely and 1- 

 rarely 2-septate longitudinally, 16-24 X 7-9.5 /x. 



On trees, Florida. 



2. Leptotrema Ravenelii (Tuck.) Fink n. comb. 



Thelotrema Ravenelii Tuck., Am. Journ. Sci. II. 25:426. 1858. 



Thallus thin, smooth to minutely wrinkled and warty, greenish to yellowish; 

 apothecia minute to small, 0.2-0.6 mm. across, immersed, the disk minute, the 

 proper exciple colored like the thallus or becoming darker; spores 8, brownish, 

 oblong-ellipsoid, 3-5-septate transversely and 1 -septate longitudinally, 13-16.X 

 7-10 /x. 



On trees, from South Carolina to Florida and Louisiana. 



