Pseudoditrichaceae consists of a single species, known only from the type specimen collected near Great Bear Lake, Northwest Territories. In the original description, Steere and Iwatsuki interpreted the endostome segments as opposite the exostome teeth. A. J. Shaw (1984) showed that the apparently opposite segments consist of two halves of adjacent alternate segments that are split to and diverge from their bases, and that the peristome should be interpreted as diplolepidous-alternate. The gametophytes are scarcely distinguishable from those of Ditrichum. This and the unique peristome warrant familial recognition.