A survey of the diatom flora of Torch Lake in northern lower Michigan was conducted. Torch
Lake is oligotrophic and has been experiencing increased growth of littoral zone algae. Diatoms were
collected and analyzed as part of a larger study in 2014. 176 diatom taxa were recorded. We present
detailed light and scanning electron microscopy observations on 11 taxa, six of which are species
new to science, three of which are new reports from the United States, and one of which is given a
new name. The new species are Fragilaria pettyorum, Gomphonema melfii, Cymbella torchiana,
Epithemia antrimiana, Nitzschia michiganiana, and Cymatopleura narwoldorum. Encyonema
evergladianum is transferred to the genus Encyonpsis resulting in the new combination Encyonopsis
evergladianum. The diatom flora of Torch Lake is similar to that of large alkaline, oligotrophic lakes
in Europe, and has several species in common.