MYRIANGI ALES 



219 



This individualization of conceptacles is greater in the West African 

 Chevalieropsis ctenotricha (Chevalieria ctenotricha) (Fig. 143); here the 

 poorly developed echinate stroma forms several conceptacles which are 

 only attached to the stroma by a narrow base. In several adjacent loculi, 

 they contain a few, narrow, clavate asci, each of which normally forms 

 8 two-celled ascospores. At maturity, the pseudoparenchyma at the 

 top of the conceptacle becomes slimy and the ascospores are liberated 

 through this slime, apparently as in the Englerulaceae. 



Fig. 143. 



-Chevalieropsis ctenotricha. Section through a dicotyledonous leaf with several 

 conceptacles. (X 33; after Arnaud, 1921.) 



With Chevalier opsis, Parodiellina and Botryosphaeria, we have tempo- 

 rarily finished with a special branch of the Myriangiales, which we shall 

 meet later in the families of the Dothideales and Sphaeriales. 



Pseudosphaeriaceae. — As the starting point of the last family 

 of the Myriangiales to be discussed here, we must go back a few steps 

 in the Dothioraceae to the stage of Bagnisiella and Dothiora. While 

 the true Dothioraceae branching off from these two genera retain their 

 broad pulvinate stromata, and only differ in that the conceptacles grad- 



c>5 o c s 



, u o o o »■» ^ — 



'/' //// /"///"• 



////// ///////// 



Fig. 144. — Pyrenophora trichostoma. Section of young stroma. (After Theissen, 1916.) 



ually lie on the upper surface of these cushions, the Pseudosphaeriaceae 

 develop in the direction of reducing the basal stromata to one concep- 

 tacle. In both families there is a tendency toward the individualization 

 of the conceptacle; in the Dothioraceae it is shown by the raising of 

 the conceptacles over the stroma and by a gradual degeneration of the 

 remaining stroma, while in the Pseudosphaeriaceae it is realized by the 

 degeneration of the whole stroma. By this degeneration and spatial 

 limitation of all the stromata, they attain in the Pseudosphaeriaceae a 

 characteristic form and become as a whole true independent fructifications, 



