47. Arthonia] 14. ARTHONIACEAE 81 



B. Spores 3-many-septate 



C. Spores 3-septate, rarely less 

 D. Apothecia round to irregular 

 E. Spores with cells unequal 



F. Spores 8-12 X 3-4.5 /i 55. A. diffusa 



F. Spores 12-15 X 3.5-4 fi 56. A. diffusella 



E. Spores with cells equal 



F. Thallus ashy white 57. A.subdiffusa 



F. Thallus yellowish or whitish 61. A. pruinosula 



D. Apothecia irregular and elongated 

 E. Apothecia not branched 

 F. Thallus smooth 



G. Apothecia 0.6-1 mm. long 54. A. luridoalba 



G. Apothecia 0.3 mm. long . . . 67. A. radiata epipastoides 



F. Thallus smooth to becoming warty 



G. Spores 16-24 X 5-7 /jl 66. A. epipastoides 



G. Spores 14-20 X 5-7.5 fi 74. A. galactitella 



E. Apothecia more or less branched 



F. Spores 16-25 /i in length 49. A. Cytisi 



F. Spores not more than 20 n in length 

 G. Apothecia stellately branched 

 H. Thallus very thin, ashy, often 



disappearing 68. A. subastroidella 



H. Thallus thin, greenish gray to whitish 



or brownish 67. A. radiata 



G. Apothecia not stellately branched 

 H. Thallus very thin or disappearing 



I. Apothecia often curved 70. A. xylographica 



I. Apothecia not curved 71. A. Hamamelidis 



H. Thallus thin, greenish gray to whitish 



or brownish 67. A. radiata angustata 



C. Spores 3-5- or more septate 

 D. Spores more than 5-septate 



E. Spores 52-70 /jl in length 76. A. platygraphidea 



E. Spores 18-25 fi in length 69. A. quintaria 



D. Spores not more than 5-septate 



E. Spores usually more than 25 fi in length 



F. Apothecia irregular and more or less branched . 64. A. excedens 



F. Apothecia elongated 63. A.complanata 



E. Spores usually less than 25 /x in length 

 F. Spores usually less than 17/i in length 



G. Thallus ashy white 73. A. asteriscus 



G. Thallus greenish gray to whitish or olive-green 



H. Apothecia 0.3-1 mm. across . . . . 62. A. polymorpha 



H. Apothecia 0.05-0.2 mm. across 72. A. torulosa 



F. Spores rarely less than 17/u in length 

 G. Apothecia elongated 



H. Spores hyaline 75. A. stictella 



H. Spores dark brown 58. A. melaspora 



G. Apothecia round to irregular 



H. Thallus ashy white and often disappearing 



I. Disk grayish pruinose 59. A. pinastri 



I. Disk black 65. A. punctiformis 



H. Thallus whitish to olive-green or greenish 

 gray to brownish 



I. On trees 60. A. reniformis 



I. On rocks; spores rarely becoming 



muriform 77. A. phaeobaea 



1. Arthonia carneorufa Willey, Int. Stud. Lich. Suppl. 52. 1887. 



Superficial thallus thin, white, smooth; apothecia minute to small, 0.1-0.3 mm. 

 across, adnate, round, the disk convex, reddish brown; tinged yellowish brown 

 within; spores ovoid-ellipsoid, 1-septate, 8-11 X 3.5-5 fi. 



On wood, Washington. 



