58 GRAPHIDACEAE 



(2) Perithecia horizontally ampulliform, ostiole roundish 



Robergea 2: 806 

 2. Perithecia vertically elongate, cylindric ; cleft obsolete 



a. Spores breaking apart into cells Microstelium 16:672 



b. Spores not breaking apart Acrospermum 2:807 



(Schizacrospermum 16:672) 



Family 29. GRAPHIDACEAE 



Zahlbruckner 87 



Mycelium parasitic on yellow green algae, forming a crustose, foliose or fruticose 

 thallus, the latter often immersed, or thallus lacking, and parasitic on lichens or on 

 bark ; perithecia single or cespitose or united in a stroma, typically oblong to elongate 

 with a cleft-like opening, more rarely disk-shaped and with an irregular often stellate 

 opening, more or less carbonous. 

 I. Perithecia separate 



1. Thallus lacking, parasitic on lichens or on bark 



Subfamily Arthoniae 89, R. 414 



a. Parasitic on lichens 



1. Spores i-celled Phacopsis R. 419 



2. Spores 2-celled Conida R. 420 



3. Spores 4-6-celled Celidium R. 425 



b. On bark 



1. Spores 2-celled Lecideopsis R. 432 



2. Spores 2-several-septate Arthonia R. 435 



3. Spores muriform Arthothelium R. 438 



2. Thallus present, crustose, or uniform 



a. Perithecia without an exciple, i. e., not margined 



Subfamily Arthoniae 89 



(1) Algae Palmella or Protococcus ; spores colorless 



(a) Spores i-septate Allarthonia 91 



(b) Spores several-septate *Plearthonis 91 



(c) Spores muriform ' Allarthothelium 241 



(2) Algae Chroolepus 



(a) Spores transeptate 

 x. Spores colorless 



(x) Spores i-septate *Diarthonis 91 



(y) Spores 2-several-septate Arthonia 89 



y. Spores brown Gymnographa 94 



(b) Spores muriform Arthothelium 91 



(3) Algae Phyllactidium 



(a) Spores i-septate *Merarthonis 91 



(b) Spores 2-several-septate Arthoniopsis 91 



b. Perithecia margined with a distinct proper exciple 



Subfamily Graphidae 92 

 (1) Thallus without cortex 

 (a) Algae Palmella 

 x. Perithecia with a single hymenium 

 ( x ) Spores colorless 

 m. Spores i-celled 



