THE GENUS KEITHIA 
Elias J. Durand 
(With Plate 8i, Containing ii Figures) 
Dr. J. J. Davis has been good enough to place in my hands for 
study material of a discomycetous fungus parasitic on Thuja, 
which was collected by him in Wisconsin. It was first found July 
14, 1908, at Mellen, Ashland Co., about twenty-five miles from 
Lake Superior, where, at two points along Bad River, Thuja was 
found bearing the fungus but not very abundantly. In July, 1909, 
the fungus was again met with in Oconto Co., in the Green Bay 
district, where it was very abundant on the same host. It seems 
probable, therefore, that the parasite is rather widely distributed 
in the northern part of Wisconsin. 
Examination of the fungus showed its affinities to be with the 
genus Keithia Sacc., and it was named provisionally K. thujina 
Durand.^ At that time I had not seen specimens of K. tetraspora, 
a European form, the typical and only described species of the 
genus. More recently, however, authentic material of that and 
of another allied species has become available which enables me 
to present the following account of this little-known parasitic 
group. 
The genus Keithia was established by Saccardo^ to include the 
single species described as Phacidiiim tetrasporum Phil. & Keith,® 
a parasite of Itiniperus, in Scotland. The genus was referred to 
the Phacidiaceae, from the other members of which it differed in 
its 4-spored asci, and its colored spores divided by a single septum 
into two unequal cells. Authentic specimens of Phacidium tetra- 
sporum collected at Forres, Scotland, June, 1880, by Rev. J. 
Keith, now in the New York State Museum of Natural History, 
at Albany, have been examined. A related species parasitic on 
Tsuga, in New Hampshire, was described by Dr. Farlow, in 1883, 
* Trans. Wise. Acad. Sci. Arts Let. 16; 756. 1909. 
“Syll. Fung. 10: 49. 1892. 
“Gardeners’ Chronicle, N. S. 14: 308. 1880. 
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