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SOUTH AFEICAN MICEOTHYEIACEAE. 
By Ethel M. Doidge. 
(With Plates XIII-XIX.) 
The family Microthyriaceae was first described by Saccardo (' SylL 
Fung.' ii, p. 658, 1883) as follows : " Simplices (i. e., without a stroma) 
Perithecia subsuperficiala, nigricantia, membranacea vel carbonacea, dimi- 
diata, applanata, contextu plerumque eximio radiato, centro pertusa vel 
astoma. Asci 4-8 spori, saepe breves." In describing fungi in those early 
days, the morphological structure of the reproductive bodies was not 
minutely studied, and gradually a large number of genera and species of 
very varying character was assigned to the Microthyriaceae. The only 
character which these forms theoretically had in common was the flattened, 
shield-like form of the perithecia. In practice even this characteristic was 
not always taken into account. During the last ten years, however, the 
enormous task of revision has been carried out chiefly by von Hohnel (1) 
and Theissen (2-10) ; a large number of genera, including all forms which 
are not strictly superficial, have been excluded, and the whole group com- 
pletely reorganised. 
In Engler's ' Die Pflanzenfamilien,' 1897, Lindau includes the Micro- 
thyriaceae in the group Perisporiales with the Erysijphaceae and the 
Perisjporiaceae ; but although they have some points in common, the Micro- 
thyriaceae differ widely from the other two families in the form of the 
fruiting body, which is not a " perithecium " in the true sense of the word, 
but a flattened, shield-shaped structure, usually in the form of a flattened 
hemisphere. Theissen classifies together all the superficial ascomycetes with 
hemispherical fruiting bodies (which he terms " thyriothecia ") in a new 
group, the Hemisphaeriales (6, 8). Within this group he distinguishes 
three families : the Microthyriaceae, with filamentous mycelium and thyrio- 
thecial membrane formed of radiating hyphae ; the Hemisjphaeriaceae, 
which differ from the Microthyriaceae in the more or less reticulate — not 
radiate — structure of the thyriothecial membrane ; and the Trichopeltaceae 
(9), which, instead of a network of filamentous hyphae, form a ribbon-like 
thallus in which the thyriothecia are developed pycnotically. 
Of these three families this paper only deals with the Microthyriaceae as 
delimited by Theissen. He assigns to this family some twenty genera, of 
which only eight have representatives described as occurring in South 
Africa. 
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